TinyCLR OS V2 RC1 RAK811 LoRaWAN library Part1

Basic connectivity

Over the weekend I have been working on a GHI Electronics TinyCLR V2  C# library for my modified RAK811 LPWAN Evaluation Board(EVB) from RAK Wireless. My initial test rig is based on an Fezduino board which has Arduino Uno R3 format socket for the EVB.

Fezduino with RAK Wisnode shield

The code has compile time options for synchronous and asynchronous operation.

   public class Program
   {
      private static UartController serialDevice;
      private const string ATCommand = "at+version\r\n";
#if TINYCLR_V2_FEZDUINO
      private static string SerialPortId = SC20100.UartPort.Uart5;
#endif

      public static void Main()
      {
         Debug.WriteLine("devMobile.IoT.Rak811.ShieldSerial starting");

         try
         {
            serialDevice = UartController.FromName(SerialPortId);

            serialDevice.SetActiveSettings(new UartSetting()
            {
               BaudRate = 9600,
               Parity = UartParity.None,
               StopBits = UartStopBitCount.One,
               Handshaking = UartHandshake.None,
               DataBits = 8
            });

            serialDevice.Enable();

#if SERIAL_ASYNC_READ
            serialDevice.DataReceived += SerialDevice_DataReceived;
#endif

            while (true)
            {
               byte[] txBuffer = UTF8Encoding.UTF8.GetBytes(ATCommand);

               int txByteCount = serialDevice.Write(txBuffer);
               Debug.WriteLine($"TX: {txByteCount} bytes");

#if SERIAL_SYNC_READ
               while( serialDevice.BytesToWrite>0)
               {
                  Debug.WriteLine($" BytesToWrite {serialDevice.BytesToWrite}");
                  Thread.Sleep(100);
               }

               int rxByteCount = serialDevice.BytesToRead;
               if (rxByteCount>0)
               {
                  byte[] rxBuffer = new byte[rxByteCount];

                  serialDevice.Read(rxBuffer);

                  Debug.WriteLine($"RX sync:{rxByteCount} bytes read");
                  String response = UTF8Encoding.UTF8.GetString(rxBuffer);
                  Debug.WriteLine($"RX sync:{response}");
               }
#endif

               Thread.Sleep(20000);
            }
         }
         catch (Exception ex)
         {
            Debug.WriteLine(ex.Message);
         }
      }


#if SERIAL_ASYNC_READ
      private static void SerialDevice_DataReceived(UartController sender, DataReceivedEventArgs e)
      {
         byte[] rxBuffer = new byte[e.Count];

         serialDevice.Read(rxBuffer, 0, e.Count);

         Debug.WriteLine($"RX Async:{e.Count} bytes read");
         String response = UTF8Encoding.UTF8.GetString(rxBuffer);
         Debug.WriteLine($"RX Async:{response}");
      }
#endif
   }

When I first ran the code I noticed the serialDevice.Read timed out before any characters were received.

The thread '<No Name>' (0x2) has exited with code 0 (0x0).
devMobile.IoT.Rak811.ShieldSerial starting
TX: 12 bytes
TX: 12 bytes
RX sync:19 bytes read
RX sync:OK V3.0.0.13.H.T3

TX: 12 bytes
RX sync:19 bytes read
RX sync:OK V3.0.0.13.H.T3

TX: 12 bytes
RX sync:19 bytes read
RX sync:OK V3.0.0.13.H.T3

I then added code to check the message had been sent and the code worked as expected. I now think, that rather than checking that the characters had been sent the short 100mSec delay was more important.

The thread '<No Name>' (0x2) has exited with code 0 (0x0).
devMobile.IoT.Rak811.ShieldSerial starting
TX: 12 bytes
 BytesToWrite 10
RX sync:19 bytes read
RX sync:OK V3.0.0.13.H.T3

TX: 12 bytes
 BytesToWrite 10
RX sync:19 bytes read
RX sync:OK V3.0.0.13.H.T3

TX: 12 bytes
 BytesToWrite 10
RX sync:19 bytes read
RX sync:OK V3.0.0.13.H.T3

I then added code to receive data asynchronously and the response to the version request was received as expected.

The thread '<No Name>' (0x2) has exited with code 0 (0x0).
devMobile.IoT.Rak811.ShieldSerial starting
TX: 12 bytes
RX Async:1 bytes read
RX Async:O
RX Async:8 bytes read
RX Async:K V3.0.0
RX Async:10 bytes read
RX Async:.13.H.T3

TX: 12 bytes
RX Async:1 bytes read
RX Async:O
RX Async:5 bytes read
RX Async:K V3.
RX Async:9 bytes read
RX Async:0.0.13.H.
RX Async:4 bytes read
RX Async:T3

RFM9X.TinyCLR V2 RC1 on Github

The source code of my GHI Electronics TinyCLR-0SV2RC1 RFM9X/SX127X library is live on GitHub. The test harness uses a Fezduino and a dragino technology LoRa shield for Arduino. I will add FezPortal, FezFeather and Fezstick support soon.

Fezduino with Dragino shield

A sample application which shows how to send/receive address/un-addresses payloads

//---------------------------------------------------------------------------------
// Copyright (c) March/April 2020, devMobile Software
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
//     http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
//
// Need one of TINYCLR_V2_SC20100DEV/TINYCLR_V2_FEZDUINO defined
//---------------------------------------------------------------------------------
namespace devMobile.IoT.Rfm9x.LoRaDeviceClient
{
	using System;
	using System.Diagnostics;
	using System.Text;
	using System.Threading;

	using GHIElectronics.TinyCLR.Pins;

	using devMobile.IoT.Rfm9x;

	class Program
   {
      static void Main()
      {
#if TINYCLR_V2_SC20100DEV
			const string DeviceName = "SC20100DEVLoRa";
#endif
#if TINYCLR_V2_FEZDUINO
			const string DeviceName = "FezduinoLoRa";
#endif
#if ADDRESSED_MESSAGES_PAYLOAD
			const string HostName = "LoRaIoT1";
#endif
			const double Frequency = 915000000.0;
			byte MessageCount = System.Byte.MaxValue;
#if TINYCLR_V2_SC20100DEV
         Rfm9XDevice rfm9XDevice = new Rfm9XDevice(SC20100.SpiBus.Spi3, SC20100.GpioPin.PA13, SC20100.GpioPin.PA14, SC20100.GpioPin.PE4);
#endif
#if TINYCLR_V2_FEZDUINO
         Rfm9XDevice rfm9XDevice = new Rfm9XDevice(SC20100.SpiBus.Spi6, SC20100.GpioPin.PB1, SC20100.GpioPin.PA15, SC20100.GpioPin.PA1);
#endif
			
			rfm9XDevice.Initialise(Frequency, paBoost: true, rxPayloadCrcOn: true);
#if DEBUG
			rfm9XDevice.RegisterDump();
#endif

			rfm9XDevice.OnReceive += Rfm9XDevice_OnReceive;
#if ADDRESSED_MESSAGES_PAYLOAD
			rfm9XDevice.Receive(UTF8Encoding.UTF8.GetBytes(DeviceName));
#else
			rfm9XDevice.Receive();
#endif
			rfm9XDevice.OnTransmit += Rfm9XDevice_OnTransmit;

			Thread.Sleep(10000);

			while (true)
			{
				string messageText = string.Format("Hello from {0} ! {1}", DeviceName, MessageCount);
				MessageCount -= 1;

				byte[] messageBytes = UTF8Encoding.UTF8.GetBytes(messageText);
				Debug.WriteLine($"{DateTime.Now:HH:mm:ss}-TX {messageBytes.Length} byte message {messageText}");
#if ADDRESSED_MESSAGES_PAYLOAD
				rfm9XDevice.Send(UTF8Encoding.UTF8.GetBytes(HostName), messageBytes);
#else
				rfm9XDevice.Send(messageBytes);
#endif
				Thread.Sleep(10000);
			}
		}

		private static void Rfm9XDevice_OnReceive(object sender, Rfm9XDevice.OnDataReceivedEventArgs e)
		{
			try
			{
				string messageText = UTF8Encoding.UTF8.GetString(e.Data);

#if ADDRESSED_MESSAGES_PAYLOAD
				string addressText = UTF8Encoding.UTF8.GetString(e.Address);

				Debug.WriteLine($@"{DateTime.Now:HH:mm:ss}-RX From {addressText} PacketSnr {e.PacketSnr} Packet RSSI {e.PacketRssi}dBm RSSI {e.Rssi}dBm = {e.Data.Length} byte message ""{messageText}""");
#else
				Debug.WriteLine($@"{DateTime.Now:HH:mm:ss}-RX PacketSnr {e.PacketSnr} Packet RSSI {e.PacketRssi}dBm RSSI {e.Rssi}dBm = {e.Data.Length} byte message ""{messageText}""");
#endif
			}
			catch (Exception ex)
			{
				Debug.WriteLine(ex.Message);
			}
		}

		private static void Rfm9XDevice_OnTransmit(object sender, Rfm9XDevice.OnDataTransmitedEventArgs e)
		{
			Debug.WriteLine($"{DateTime.Now:HH:mm:ss}-TX Done");
		}
	}
}

The addressing support is pretty basic as my goal was a library that I could extend with optional functionality like tamper detection via signing and privacy via payload encryption, mesh network support etc.

The library works but should be treated as late beta.

TinyCLR OS V2 RC1 LoRa library Part3

Why are Transmit Interrupts broken?

The receive using interrupts appeared to be working but transmit with interrupts I could only send a couple of messages before confirmations stopped.

I had read about restrictions for interrupts pins e.g. PA1 & PB1 can’t be used at the same time, but PA1 and PB2 can, which got me thinking…

In my dragino shield based setup Arduino D2(PA1) is the interrupt(IRQ) line and Arduino D10(PB1) is chip select (CS) so I changed the pins with jumper wires just incase.

Fezduino connected to Dragino LoRa shield with jumpers

I tried several different configurations of CS and IRQ pins and none worked.

On other embedded .net platforms I have written Serial Peripheral Interface(SPI) based drivers for (e.g. Wilderness Labs Meadow and the nanoFramework) there had been issues with the use of device.Write vs. device. TransferFullDuplex (or its equivalent).

The RegisterWriteByte method in the event handler appeared to be the problem so I tried modifying it.

public void RegisterWriteByte(byte address, byte value)
{
   byte[] writeBuffer = new byte[] { address |= RegisterAddressWriteMask, value };
   Debug.Assert(rfm9XLoraModem != null);

   rfm9XLoraModem.Write(writeBuffer);
}

Became

public void RegisterWriteByte(byte address, byte value)
{
   byte[] writeBuffer = new byte[] { address |= RegisterAddressWriteMask, value };
   byte[] readBuffer = new byte[2];
   Debug.Assert(rfm9XLoraModem != null);

   rfm9XLoraModem.TransferFullDuplex(writeBuffer, readBuffer);
}

In the diagnostic output I could see confirmations arriving

The thread '<No Name>' (0x2) has exited with code 0 (0x0).
Sending 13 bytes message Hello LoRa 1!
RegIrqFlags 0X08
Transmit-Done
Sending 13 bytes message Hello LoRa 2!
RegIrqFlags 0X08
Transmit-Done
Sending 13 bytes message Hello LoRa 3!
RegIrqFlags 0X08
Transmit-Done
Sending 13 bytes message Hello LoRa 4!
RegIrqFlags 0X08
Transmit-Done
Sending 13 bytes message Hello LoRa 5!
RegIrqFlags 0X08
Transmit-Done
Sending 13 bytes message Hello LoRa 6!
RegIrqFlags 0X08
Transmit-Done

This was clue it might be a timing problem, so I took a closer look at how the SPI port was configured. After some experimentation I found that by adding a small ChipSelectHoldTime the .Write statements worked.

When I went back and checked there had also been some timing “tweaks” required to get my .Net Microframework LoRa library to work reliably.

public Rfm9XDevice(string spiPortName, int chipSelectPin, int resetPin, int interruptPin)
{
   GpioController gpioController = GpioController.GetDefault();

   GpioPin chipSelectGpio = gpioController.OpenPin(chipSelectPin);

   var settings = new SpiConnectionSettings()
   {
      ChipSelectType = SpiChipSelectType.Gpio,
      ChipSelectLine = chipSelectGpio,
      Mode = SpiMode.Mode0,
      ClockFrequency = 500000,
      ChipSelectActiveState = false,
      //ChipSelectHoldTime = new TimeSpan(50),
      //ChipSelectHoldTime = new TimeSpan(25),
      //ChipSelectHoldTime = new TimeSpan(10),
      ChipSelectHoldTime = new TimeSpan(5),
      //ChipSelectHoldTime = new TimeSpan(1),
   };

   SpiController spiController = SpiController.FromName(spiPortName);

   rfm9XLoraModem = spiController.GetDevice(settings);

   // Factory reset pin configuration
   GpioPin resetGpioPin = gpioController.OpenPin(resetPin);
   resetGpioPin.SetDriveMode(GpioPinDriveMode.Output);
   resetGpioPin.Write(GpioPinValue.Low);
   Thread.Sleep(10);
   resetGpioPin.Write(GpioPinValue.High);
   Thread.Sleep(10);

   // Interrupt pin for RX message & TX done notification 
   InterruptGpioPin = gpioController.OpenPin(interruptPin);
   InterruptGpioPin.SetDriveMode(GpioPinDriveMode.Input);

   InterruptGpioPin.ValueChanged += InterruptGpioPin_ValueChanged;
}

In the diagnostic output I could see confirmations arriving

...
Sending 16 bytes message Hello LoRa 1115!
RegIrqFlags 0X08
Transmit-Done
Sending 16 bytes message Hello LoRa 1116!
RegIrqFlags 0X08
Transmit-Done
Sending 16 bytes message Hello LoRa 1117!
RegIrqFlags 0X08
Transmit-Done
Sending 16 bytes message Hello LoRa 1118!
RegIrqFlags 0X08
Transmit-Done
Sending 16 bytes message Hello LoRa 1119!
RegIrqFlags 0X08
Transmit-Done
Sending 16 bytes message Hello LoRa 1120!
RegIrqFlags 0X08
Transmit-Done
Sending 16 bytes message Hello LoRa 1121!
RegIrqFlags 0X08
Transmit-Done
Sending 16 bytes message Hello LoRa 1122!
RegIrqFlags 0X08
The program '[13] TinyCLR application: Managed' has exited with code 0 (0x0).

After some soak testing it looks like the ChipSelectHoldTime modification works pretty reliably but I will need watch for issues.

EDIT: After a long walk I have updated the code to use TransferFullDuplex rather than add a ChipSelectHoldTime.

TinyCLR OS V2 RC1 LoRa library Part2

Receive and Transmit

The first step was to confirm the transmission of messages with polled completion confirmation was working as expected.

   class Program
   {
      static void Main()
      {
#if TINYCLR_V2_SC20100DEV
         Rfm9XDevice rfm9XDevice = new Rfm9XDevice(SC20100.SpiBus.Spi3, SC20100.GpioPin.PA13, SC20100.GpioPin.PA14);
#endif
#if TINYCLR_V2_FEZDUINO
         Rfm9XDevice rfm9XDevice = new Rfm9XDevice(SC20100.SpiBus.Spi6, SC20100.GpioPin.PB1, SC20100.GpioPin.PA15);
#endif
         int SendCount = 0;

         // Put device into LoRa + Sleep mode
         rfm9XDevice.RegisterWriteByte(0x01, 0b10000000); // RegOpMode 

         // Set the frequency to 915MHz
         byte[] frequencyWriteBytes = { 0xE4, 0xC0, 0x00 }; // RegFrMsb, RegFrMid, RegFrLsb
         rfm9XDevice.RegisterWrite(0x06, frequencyWriteBytes);

         // More power PA Boost
         rfm9XDevice.RegisterWriteByte(0x09, 0b10000000); // RegPaConfig

         rfm9XDevice.RegisterDump();

         while (true)
         {
            rfm9XDevice.RegisterWriteByte(0x0E, 0x0); // RegFifoTxBaseAddress 

            // Set the Register Fifo address pointer
            rfm9XDevice.RegisterWriteByte(0x0D, 0x0); // RegFifoAddrPtr 

            string messageText = $"Hello LoRa {SendCount += 1}!";
               
            // load the message into the fifo
            byte[] messageBytes = UTF8Encoding.UTF8.GetBytes(messageText);
            rfm9XDevice.RegisterWrite(0x0, messageBytes); // RegFifo

            // Set the length of the message in the fifo
            rfm9XDevice.RegisterWriteByte(0x22, (byte)messageBytes.Length); // RegPayloadLength

            Debug.WriteLine($"Sending {messageBytes.Length} bytes message {messageText}");
            /// Set the mode to LoRa + Transmit
            rfm9XDevice.RegisterWriteByte(0x01, 0b10000011); // RegOpMode 

            // Wait until send done, no timeouts in PoC
            Debug.WriteLine("Send-wait");
            byte IrqFlags = rfm9XDevice.RegisterReadByte(0x12); // RegIrqFlags
            while ((IrqFlags & 0b00001000) == 0)  // wait until TxDone cleared
            {
               Thread.Sleep(10);
               IrqFlags = rfm9XDevice.RegisterReadByte(0x12); // RegIrqFlags
               Debug.WriteLine(".");
            }
            rfm9XDevice.RegisterWriteByte(0x12, 0b00001000); // clear TxDone bit
            Debug.WriteLine("Send-Done");

            Thread.Sleep(30000);
         }
      }
   }

The diagnostic output shows messages being sent and on another device I could see the messages arriving. I do wonder why the first message often takes so long to send?

Register dump
Register 0x00 - Value 0Xc3
Register 0x01 - Value 0X80
Register 0x02 - Value 0X1a
Register 0x03 - Value 0X0b
Register 0x04 - Value 0X00
Register 0x05 - Value 0X52
Register 0x06 - Value 0Xe4
Register 0x07 - Value 0Xc0
Register 0x08 - Value 0X00
Register 0x09 - Value 0X80
Register 0x0a - Value 0X09
Register 0x0b - Value 0X2b
Register 0x0c - Value 0X20
Register 0x0d - Value 0X01
Register 0x0e - Value 0X80
Register 0x0f - Value 0X00
Register 0x10 - Value 0X00
Register 0x11 - Value 0X00
Register 0x12 - Value 0X00
Register 0x13 - Value 0X00
Register 0x14 - Value 0X00
Register 0x15 - Value 0X00
Register 0x16 - Value 0X00
Register 0x17 - Value 0X00
Register 0x18 - Value 0X10
Register 0x19 - Value 0X00
Register 0x1a - Value 0X00
Register 0x1b - Value 0X00
Register 0x1c - Value 0X00
Register 0x1d - Value 0X72
Register 0x1e - Value 0X70
Register 0x1f - Value 0X64
Register 0x20 - Value 0X00
Register 0x21 - Value 0X08
Register 0x22 - Value 0X01
Register 0x23 - Value 0Xff
Register 0x24 - Value 0X00
Register 0x25 - Value 0X00
Register 0x26 - Value 0X04
Register 0x27 - Value 0X00
Register 0x28 - Value 0X00
Register 0x29 - Value 0X00
Register 0x2a - Value 0X00
Register 0x2b - Value 0X00
Register 0x2c - Value 0X00
Register 0x2d - Value 0X50
Register 0x2e - Value 0X14
Register 0x2f - Value 0X45
Register 0x30 - Value 0X55
Register 0x31 - Value 0Xc3
Register 0x32 - Value 0X05
Register 0x33 - Value 0X27
Register 0x34 - Value 0X1c
Register 0x35 - Value 0X0a
Register 0x36 - Value 0X03
Register 0x37 - Value 0X0a
Register 0x38 - Value 0X42
Register 0x39 - Value 0X12
Register 0x3a - Value 0X49
Register 0x3b - Value 0X1d
Register 0x3c - Value 0X00
Register 0x3d - Value 0Xaf
Register 0x3e - Value 0X00
Register 0x3f - Value 0X00
Register 0x40 - Value 0X00
Register 0x41 - Value 0X00
Register 0x42 - Value 0X12
Sending 13 bytes message Hello LoRa 1!
Send-wait
.
.
.
.
.
Send-Done
Sending 13 bytes message Hello LoRa 2!
Send-wait
Send-Done
Sending 13 bytes message Hello LoRa 3!
Send-wait
Send-Done
Sending 13 bytes message Hello LoRa 4!
Send-wait
Send-Done
Sending 13 bytes message Hello LoRa 5!
Send-wait
Send-Done
Sending 13 bytes message Hello LoRa 6!
Send-wait
Send-Done

The second step was to confirm the polled reception of messages was working as expected.

   class Program
   {
      static void Main()
      {
#if TINYCLR_V2_SC20100DEV
         Rfm9XDevice rfm9XDevice = new Rfm9XDevice(SC20100.SpiBus.Spi3, SC20100.GpioPin.PA13, SC20100.GpioPin.PA14);
#endif
#if TINYCLR_V2_FEZDUINO
         Rfm9XDevice rfm9XDevice = new Rfm9XDevice(SC20100.SpiBus.Spi6, SC20100.GpioPin.PB1, SC20100.GpioPin.PA15);
#endif


         // Put device into LoRa + Sleep mode
         rfm9XDevice.RegisterWriteByte(0x01, 0b10000000); // RegOpMode 

         // Set the frequency to 915MHz
         byte[] frequencyWriteBytes = { 0xE4, 0xC0, 0x00 }; // RegFrMsb, RegFrMid, RegFrLsb
         rfm9XDevice.RegisterWrite(0x06, frequencyWriteBytes);

         rfm9XDevice.RegisterWriteByte(0x0F, 0x0); // RegFifoRxBaseAddress 

         rfm9XDevice.RegisterWriteByte(0x01, 0b10000101); // RegOpMode set LoRa & RxContinuous

         while (true)
         {
            // Wait until a packet is received, no timeouts in PoC
            Debug.WriteLine("Receive-Wait");
            byte irqFlags = rfm9XDevice.RegisterReadByte(0x12); // RegIrqFlags
            while ((irqFlags & 0b01000000) == 0)  // wait until RxDone cleared
            {
               Thread.Sleep(100);
               irqFlags = rfm9XDevice.RegisterReadByte(0x12); // RegIrqFlags
               //Debug.Write(".");
            }
            Debug.WriteLine("");
            Debug.WriteLine($"RegIrqFlags 0X{irqFlags:X2}");
            Debug.WriteLine("Receive-Message");
            byte currentFifoAddress = rfm9XDevice.RegisterReadByte(0x10); // RegFifiRxCurrent
            rfm9XDevice.RegisterWriteByte(0x0d, currentFifoAddress); // RegFifoAddrPtr

            byte numberOfBytes = rfm9XDevice.RegisterReadByte(0x13); // RegRxNbBytes

            byte[] messageBytes = rfm9XDevice.RegisterRead(0x00, numberOfBytes); // RegFifo

            rfm9XDevice.RegisterWriteByte(0x0d, 0);
            rfm9XDevice.RegisterWriteByte(0x12, 0b11111111); // RegIrqFlags clear all the bits

            string messageText = UTF8Encoding.UTF8.GetString(messageBytes);
            Debug.WriteLine($"Received {messageBytes.Length} byte message {messageText}");

            Debug.WriteLine("Receive-Done");
         }
      }
   }

The diagnostic output shows messages being received from one of my other devices.

The thread ” (0x2) has exited with code 0 (0x0).
Receive-Wait

RegIrqFlags 0X50
Receive-Message
Received 23 byte message �LoRaIoT1N3WT 18.8,H 78
Receive-Done
Receive-Wait

RegIrqFlags 0X50
Receive-Message
Received 23 byte message �LoRaIoT1N3WT 18.8,H 78
Receive-Done
Receive-Wait

The next step was to confirm the interrupt driven reception of messages was working as expected.

   class Program
   {
      static void Main()
      {
#if TINYCLR_V2_SC20100DEV
         Rfm9XDevice rfm9XDevice = new Rfm9XDevice(SC20100.SpiBus.Spi3, SC20100.GpioPin.PA13, SC20100.GpioPin.PA14, SC20100.GpioPin.PE4);
#endif
#if TINYCLR_V2_FEZDUINO
         Rfm9XDevice rfm9XDevice = new Rfm9XDevice(SC20100.SpiBus.Spi6, SC20100.GpioPin.PB1, SC20100.GpioPin.PA15, SC20100.GpioPin.PA1);
#endif

         // Put device into LoRa + Sleep mode
         rfm9XDevice.RegisterWriteByte(0x01, 0b10000000); // RegOpMode 

         // Set the frequency to 915MHz
         byte[] frequencyWriteBytes = { 0xE4, 0xC0, 0x00 }; // RegFrMsb, RegFrMid, RegFrLsb
         rfm9XDevice.RegisterWrite(0x06, frequencyWriteBytes);

         rfm9XDevice.RegisterWriteByte(0x0F, 0x0); // RegFifoRxBaseAddress 

         rfm9XDevice.RegisterWriteByte(0x40, 0b00000000); // RegDioMapping1 0b00000000 DI0 RxReady & TxReady

         rfm9XDevice.RegisterWriteByte(0x01, 0b10000101); // RegOpMode set LoRa & RxContinuous

         rfm9XDevice.RegisterDump();

         Debug.WriteLine("Receive-Wait");
         Thread.Sleep(Timeout.Infinite);
      }
   }

      private void InterruptGpioPin_ValueChanged(GpioPin sender, GpioPinValueChangedEventArgs e)
      {
         if (e.Edge != GpioPinEdge.RisingEdge)
         {
            return;
         }

         byte irqFlags = this.RegisterReadByte(0x12); // RegIrqFlags
         Debug.WriteLine($"RegIrqFlags 0X{irqFlags:x2}");
         if ((irqFlags & 0b01000000) == 0b01000000)  // RxDone 
         {
            Debug.WriteLine("Receive-Message");
            byte currentFifoAddress = this.RegisterReadByte(0x10); // RegFifiRxCurrent
            this.RegisterWriteByte(0x0d, currentFifoAddress); // RegFifoAddrPtr

            byte numberOfBytes = this.RegisterReadByte(0x13); // RegRxNbBytes

            // Get number of bytes in the message
            byte[] messageBytes = this.RegisterRead(0x00, numberOfBytes);

            string messageText = UTF8Encoding.UTF8.GetString(messageBytes);
            Debug.WriteLine($"Received {messageBytes.Length} byte message {messageText}");
         }

         this.RegisterWriteByte(0x12, 0xff);// RegIrqFlags
      }

The diagnostic output shows messages being received from one of my other devices.

The thread '<No Name>' (0x2) has exited with code 0 (0x0).
Receive-Wait
RegIrqFlags 0X50
Receive-Message
Received 23 byte message  �LoRaIoT1N3WT 18.8,H 78
RegIrqFlags 0X50
Receive-Message
Received 23 byte message  �LoRaIoT1N3WT 18.7,H 79

The final step was to confirm the interrupt driven transmission of messages was working as expected.

   class Program
   {
      static void Main()
      {
#if TINYCLR_V2_SC20100DEV
         Rfm9XDevice rfm9XDevice = new Rfm9XDevice(SC20100.SpiBus.Spi3, SC20100.GpioPin.PA13, SC20100.GpioPin.PA14, SC20100.GpioPin.PE4);
#endif
#if TINYCLR_V2_FEZDUINO
         Rfm9XDevice rfm9XDevice = new Rfm9XDevice(SC20100.SpiBus.Spi6, SC20100.GpioPin.PB1, SC20100.GpioPin.PA15, SC20100.GpioPin.PA1); // Doesn't work
#endif
         int SendCount = 0;

         // Put device into LoRa + Sleep mode
         rfm9XDevice.RegisterWriteByte(0x01, 0b10000000); // RegOpMode 

         // Set the frequency to 915MHz
         byte[] frequencyWriteBytes = { 0xE4, 0xC0, 0x00 }; // RegFrMsb, RegFrMid, RegFrLsb
         rfm9XDevice.RegisterWrite(0x06, frequencyWriteBytes);

         // More power PA Boost
         rfm9XDevice.RegisterWriteByte(0x09, 0b10000000); // RegPaConfig

         // Interrupt on TxDone
         rfm9XDevice.RegisterWriteByte(0x40, 0b01000000); // RegDioMapping1 0b00000000 DI0 TxDone

         while (true)
         {
            // Set the Register Fifo address pointer
            rfm9XDevice.RegisterWriteByte(0x0E, 0x00); // RegFifoTxBaseAddress 

            // Set the Register Fifo address pointer
            rfm9XDevice.RegisterWriteByte(0x0D, 0x0); // RegFifoAddrPtr 

            string messageText = $"Hello LoRa {SendCount += 1}!";

            // load the message into the fifo
            byte[] messageBytes = UTF8Encoding.UTF8.GetBytes(messageText);
            rfm9XDevice.RegisterWrite(0x0, messageBytes); // RegFifo 

            // Set the length of the message in the fifo
            rfm9XDevice.RegisterWriteByte(0x22, (byte)messageBytes.Length); // RegPayloadLength
            Debug.WriteLine($"Sending {messageBytes.Length} bytes message {messageText}");
            rfm9XDevice.RegisterWriteByte(0x01, 0b10000011); // RegOpMode 

            Thread.Sleep(10000);
         }
      }
   }


private void InterruptGpioPin_ValueChanged(GpioPin sender, GpioPinValueChangedEventArgs e)
      {
         if (e.Edge != GpioPinEdge.RisingEdge)
         {
            return;
         }

         byte irqFlags = this.RegisterReadByte(0x12); // RegIrqFlags
         Debug.WriteLine($"RegIrqFlags 0X{irqFlags:x2}");

         if ((irqFlags & 0b00001000) == 0b00001000)  // TxDone
         {
            Debug.WriteLine("Transmit-Done");
         }

         this.RegisterWriteByte(0x12, 0xff);// RegIrqFlags
      }

The diagnostic output shows messages being sent but after the first message (sometimes the second or third) there are no confirmations.

The thread ” (0x2) has exited with code 0 (0x0).
Sending 13 bytes message Hello LoRa 1!
RegIrqFlags 0X08
Transmit-Done
Sending 13 bytes message Hello LoRa 2!
Sending 13 bytes message Hello LoRa 3!
Sending 13 bytes message Hello LoRa 4!
Sending 13 bytes message Hello LoRa 5!
Sending 13 bytes message Hello LoRa 6!
Sending 13 bytes message Hello LoRa 7!
Sending 13 bytes message Hello LoRa 8!
Sending 13 bytes message Hello LoRa 9!
Sending 14 bytes message Hello LoRa 10!
Sending 14 bytes message Hello LoRa 11!
Sending 14 bytes message Hello LoRa 12!
Sending 14 bytes message Hello LoRa 13!
Sending 14 bytes message Hello LoRa 14!

It looks like something has been broken (possibly by RC1) in my implementation of interrupt driven transmission of messages.

TinyCLR OS V2 RC1 LoRa library Part1

The Basics

A week ago a selection of Single Board Computers(SBC) arrived from GHI Electronics. Previously I had been working with a SC20100 Dev board which has mikroBUS Click sockets which limited my peripheral options. There were several different device form factors in the package so I started with a Fezduino and Dragino LoRa shield for Arduino.

Fezduino with Dragino Shield

Need to be careful not to push the Dragino shield in too far as a couple of the pins (one is not connected and the other is IOREF) will contact the Micro SD card slot. (I have put a strip of Duct tape on the top of the Micro SD card socket)

Fezduino pin clearance

The first step was to get basic connectivity sorted. I opened the RFM9XLoRa-TinyCLR repository and modified the Serial Peripheral Interface(SPI) and chip select(CS) settings of the ShieldSPI project, then updated the NuGet packages (public feed rather than my local preview files).

Dragino LoRa Shield for Arduino pins

I have left the TinyCLR V1 configuration in for backward compatibility

#if TINYCLR_V1_FEZDUINO
            ChipSelectLine = FEZ.GpioPin.D10,
#endif
#if TINYCLR_V2_SC20100DEV
            ChipSelectLine = GHIElectronics.TinyCLR.Devices.Gpio.GpioController.GetDefault().OpenPin(SC20100.GpioPin.PA13),
#endif
#if TINYCLR_V2_FEZDUINO
            ChipSelectLine = GHIElectronics.TinyCLR.Devices.Gpio.GpioController.GetDefault().OpenPin(GHIElectronics.TinyCLR.Pins.SC20100.GpioPin.PB1),
#endif

When I ran the application in Visual Studio I could reliably read the RegVersion register.

The thread '<No Name>' (0x2) has exited with code 0 (0x0).
Value = 0x00-12
Value = 0x00-12
Value = 0x00-12
Value = 0x00-12
Value = 0x00-12
Value = 0x00-12
The program '[5] TinyCLR application: Managed' has exited with code 0 (0x0).

The next step was to modify the RegisterScan project to check I could read all the SX127X configuration registers.

  class Program
   {
      static void Main()
      {
#if TINYCLR_V2_SC20100DEV
         Rfm9XDevice rfm9XDevice = new Rfm9XDevice(SC20100.SpiBus.Spi3, SC20100.GpioPin.PA13);
#endif
#if TINYCLR_V2_FEZDUINO
         Rfm9XDevice rfm9XDevice = new Rfm9XDevice(SC20100.SpiBus.Spi6, SC20100.GpioPin.PB1);
#endif

         while (true)
         {
            for (byte registerIndex = 0; registerIndex <= 0x42; registerIndex++)
            {
               byte registerValue = rfm9XDevice.RegisterReadByte(registerIndex);

               Debug.WriteLine($"Register 0x{registerIndex:x2} - Value 0X{registerValue:x2}");
            }
            Debug.WriteLine("");

            Thread.Sleep(10000);
         }
      }
   }

When I ran the application in Visual Studio I could reliably read the registers 0x00 through 0x42.

The thread '<No Name>' (0x2) has exited with code 0 (0x0).
Register 0x00 - Value 0X00
Register 0x01 - Value 0X09
Register 0x02 - Value 0X1a
Register 0x03 - Value 0X0b
Register 0x04 - Value 0X00
Register 0x05 - Value 0X52
Register 0x06 - Value 0X6c
Register 0x07 - Value 0X80
Register 0x08 - Value 0X00
Register 0x09 - Value 0X4f
Register 0x0a - Value 0X09
Register 0x0b - Value 0X2b
Register 0x0c - Value 0X20
Register 0x0d - Value 0X08
Register 0x0e - Value 0X02
Register 0x0f - Value 0X0a
Register 0x10 - Value 0Xff
Register 0x11 - Value 0X71
Register 0x12 - Value 0X15
Register 0x13 - Value 0X0b
Register 0x14 - Value 0X28
Register 0x15 - Value 0X0c
Register 0x16 - Value 0X12
Register 0x17 - Value 0X47
Register 0x18 - Value 0X32
Register 0x19 - Value 0X3e
Register 0x1a - Value 0X00
Register 0x1b - Value 0X00
Register 0x1c - Value 0X00
Register 0x1d - Value 0X00
Register 0x1e - Value 0X00
Register 0x1f - Value 0X40
Register 0x20 - Value 0X00
Register 0x21 - Value 0X00
Register 0x22 - Value 0X00
Register 0x23 - Value 0X00
Register 0x24 - Value 0X05
Register 0x25 - Value 0X00
Register 0x26 - Value 0X03
Register 0x27 - Value 0X93
Register 0x28 - Value 0X55
Register 0x29 - Value 0X55
Register 0x2a - Value 0X55
Register 0x2b - Value 0X55
Register 0x2c - Value 0X55
Register 0x2d - Value 0X55
Register 0x2e - Value 0X55
Register 0x2f - Value 0X55
Register 0x30 - Value 0X90
Register 0x31 - Value 0X40
Register 0x32 - Value 0X40
Register 0x33 - Value 0X00
Register 0x34 - Value 0X00
Register 0x35 - Value 0X0f
Register 0x36 - Value 0X00
Register 0x37 - Value 0X00
Register 0x38 - Value 0X00
Register 0x39 - Value 0Xf5
Register 0x3a - Value 0X20
Register 0x3b - Value 0X82
Register 0x3c - Value 0Xfb
Register 0x3d - Value 0X02
Register 0x3e - Value 0X80
Register 0x3f - Value 0X40
Register 0x40 - Value 0X00
Register 0x41 - Value 0X00
Register 0x42 - Value 0X12

The next step was to modify the RegisterReadAndWrite project to check I could read and write the SX127X configuration registers.

     class Program
   {
      static void Main()
      {
#if TINYCLR_V2_SC20100DEV
         Rfm9XDevice rfm9XDevice = new Rfm9XDevice(SC20100.SpiBus.Spi3, SC20100.GpioPin.PA13, SC20100.GpioPin.PA14);
#endif
#if TINYCLR_V2_FEZDUINO
         Rfm9XDevice rfm9XDevice = new Rfm9XDevice(SC20100.SpiBus.Spi6, SC20100.GpioPin.PB1, SC20100.GpioPin.PA15);
#endif

         rfm9XDevice.RegisterDump();

         while (true)
         {
            Debug.WriteLine("Read RegOpMode (read byte)");
            Byte regOpMode1 = rfm9XDevice.RegisterReadByte(0x1);
            Debug.WriteLine($"RegOpMode 0x{regOpMode1:x2}");

            Debug.WriteLine("Set LoRa mode and sleep mode (write byte)");
            rfm9XDevice.RegisterWriteByte(0x01, 0b10000000);

            Debug.WriteLine("Read RegOpMode (read byte)");
            Byte regOpMode2 = rfm9XDevice.RegisterReadByte(0x1);
            Debug.WriteLine($"RegOpMode 0x{regOpMode2:x2}");

            Debug.WriteLine("Read the preamble (read word)");
            ushort preamble = rfm9XDevice.RegisterReadWord(0x20);
            Debug.WriteLine($"Preamble 0x{preamble:x2}");

            Debug.WriteLine("Set the preamble to 0x80 (write word)");
            rfm9XDevice.RegisterWriteWord(0x20, 0x80);

            Debug.WriteLine("Read the center frequency (read byte array)");
            byte[] frequencyReadBytes = rfm9XDevice.RegisterRead(0x06, 3);
            Debug.WriteLine($"Frequency Msb 0x{frequencyReadBytes[0]:x2} Mid 0x{frequencyReadBytes[1]:x2} Lsb 0x{frequencyReadBytes[2]:x2}");

            Debug.WriteLine("Set the center frequency to 915MHz (write byte array)");
            byte[] frequencyWriteBytes = { 0xE4, 0xC0, 0x00 };
            rfm9XDevice.RegisterWrite(0x06, frequencyWriteBytes);

            rfm9XDevice.RegisterDump();

            Thread.Sleep(30000);
         }
      }

When I ran the application in Visual Studio I could read and write register values.

The thread '<No Name>' (0x2) has exited with code 0 (0x0).
Register dump
Register 0x00 - Value 0X00
Register 0x01 - Value 0X09
Register 0x02 - Value 0X1a
Register 0x03 - Value 0X0b
Register 0x04 - Value 0X00
Register 0x05 - Value 0X52
Register 0x06 - Value 0X6c
Register 0x07 - Value 0X80
Register 0x08 - Value 0X00
Register 0x09 - Value 0X4f
Register 0x0a - Value 0X09
Register 0x0b - Value 0X2b
Register 0x0c - Value 0X20
Register 0x0d - Value 0X08
Register 0x0e - Value 0X02
Register 0x0f - Value 0X0a
Register 0x10 - Value 0Xff
Register 0x11 - Value 0X71
Register 0x12 - Value 0X15
Register 0x13 - Value 0X0b
Register 0x14 - Value 0X28
Register 0x15 - Value 0X0c
Register 0x16 - Value 0X12
Register 0x17 - Value 0X47
Register 0x18 - Value 0X32
Register 0x19 - Value 0X3e
Register 0x1a - Value 0X00
Register 0x1b - Value 0X00
Register 0x1c - Value 0X00
Register 0x1d - Value 0X00
Register 0x1e - Value 0X00
Register 0x1f - Value 0X40
Register 0x20 - Value 0X00
Register 0x21 - Value 0X00
Register 0x22 - Value 0X00
Register 0x23 - Value 0X00
Register 0x24 - Value 0X05
Register 0x25 - Value 0X00
Register 0x26 - Value 0X03
Register 0x27 - Value 0X93
Register 0x28 - Value 0X55
Register 0x29 - Value 0X55
Register 0x2a - Value 0X55
Register 0x2b - Value 0X55
Register 0x2c - Value 0X55
Register 0x2d - Value 0X55
Register 0x2e - Value 0X55
Register 0x2f - Value 0X55
Register 0x30 - Value 0X90
Register 0x31 - Value 0X40
Register 0x32 - Value 0X40
Register 0x33 - Value 0X00
Register 0x34 - Value 0X00
Register 0x35 - Value 0X0f
Register 0x36 - Value 0X00
Register 0x37 - Value 0X00
Register 0x38 - Value 0X00
Register 0x39 - Value 0Xf5
Register 0x3a - Value 0X20
Register 0x3b - Value 0X82
Register 0x3c - Value 0Xfa
Register 0x3d - Value 0X02
Register 0x3e - Value 0X80
Register 0x3f - Value 0X40
Register 0x40 - Value 0X00
Register 0x41 - Value 0X00
Register 0x42 - Value 0X12
Read RegOpMode (read byte)
RegOpMode 0x09
Set LoRa mode and sleep mode (write byte)
Read RegOpMode (read byte)
RegOpMode 0x80
Read the preamble (read word)
Preamble 0x08
Set the preamble to 0x80 (write word)
Read the center frequency (read byte array)
Frequency Msb 0x6c Mid 0x80 Lsb 0x00
Set the center frequency to 915MHz (write byte array)
Register dump
Register 0x00 - Value 0Xc3
Register 0x01 - Value 0X80
Register 0x02 - Value 0X1a
Register 0x03 - Value 0X0b
Register 0x04 - Value 0X00
Register 0x05 - Value 0X52
Register 0x06 - Value 0Xe4
Register 0x07 - Value 0Xc0
Register 0x08 - Value 0X00
Register 0x09 - Value 0X4f
Register 0x0a - Value 0X09
Register 0x0b - Value 0X2b
Register 0x0c - Value 0X20
Register 0x0d - Value 0X01
Register 0x0e - Value 0X80
Register 0x0f - Value 0X00
Register 0x10 - Value 0X00
Register 0x11 - Value 0X00
Register 0x12 - Value 0X00
Register 0x13 - Value 0X00
Register 0x14 - Value 0X00
Register 0x15 - Value 0X00
Register 0x16 - Value 0X00
Register 0x17 - Value 0X00
Register 0x18 - Value 0X10
Register 0x19 - Value 0X00
Register 0x1a - Value 0X00
Register 0x1b - Value 0X00
Register 0x1c - Value 0X00
Register 0x1d - Value 0X72
Register 0x1e - Value 0X70
Register 0x1f - Value 0X64
Register 0x20 - Value 0X80
Register 0x21 - Value 0X00
Register 0x22 - Value 0X01
Register 0x23 - Value 0Xff
Register 0x24 - Value 0X00
Register 0x25 - Value 0X00
Register 0x26 - Value 0X04
Register 0x27 - Value 0X00
Register 0x28 - Value 0X00
Register 0x29 - Value 0X00
Register 0x2a - Value 0X00
Register 0x2b - Value 0X00
Register 0x2c - Value 0X00
Register 0x2d - Value 0X50
Register 0x2e - Value 0X14
Register 0x2f - Value 0X45
Register 0x30 - Value 0X55
Register 0x31 - Value 0Xc3
Register 0x32 - Value 0X05
Register 0x33 - Value 0X27
Register 0x34 - Value 0X1c
Register 0x35 - Value 0X0a
Register 0x36 - Value 0X03
Register 0x37 - Value 0X0a
Register 0x38 - Value 0X42
Register 0x39 - Value 0X12
Register 0x3a - Value 0X49
Register 0x3b - Value 0X1d
Register 0x3c - Value 0X00
Register 0x3d - Value 0Xaf
Register 0x3e - Value 0X00
Register 0x3f - Value 0X00
Register 0x40 - Value 0X00
Register 0x41 - Value 0X00
Register 0x42 - Value 0X12

At this point I was confident that I could hardware reset the shield and read/modify registers on the SX127X.

RAK811LoRaWAN.NetNF on Github

The source code of my nanoFramework RAK811 Module library is now available on GitHub. My test harness (I plan to add more nanoFramework supported devices) uses an STM769 Discovery and a modified RAK811 LPWAN Evaluation Board(EVB).

STM32F691Discovery with EVB plugged into Arduino headers

A sample application which shows how to connect using Over the Air Activation(OTAA) or Activation By Personalisation(ABP) then send and receive byte array/Binary Coded Decimal(BCD) messages .

//---------------------------------------------------------------------------------
// Copyright (c) June 2020, devMobile Software
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
//     http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
//
//---------------------------------------------------------------------------------
#define ST_STM32F769I_DISCOVERY      // nanoff --target ST_STM32F769I_DISCOVERY --update 
#define PAYLOAD_BCD
//#define PAYLOAD_BYTES
#define OTAA
//#define ABP
#define CONFIRMED
namespace devMobile.IoT.Rak811LoRaWanDeviceClient
{
   using System;
   using System.Threading;
   using System.Diagnostics;
   using Windows.Devices.SerialCommunication;

   using devMobile.IoT.LoRaWan;

   public class Program
   {
#if ST_STM32F769I_DISCOVERY
      private const string SerialPortId = "COM6";
#endif
#if OTAA
      private const string DevEui = "...";
      private const string AppEui = "...";
      private const string AppKey = "...";
#endif
#if ABP
      private const string DevAddress = "...";
      private const string NwksKey = "...";
      private const string AppsKey = "...";
#endif
      private const string Region = "AS923";
      private static readonly TimeSpan JoinTimeOut = new TimeSpan(0, 0, 10);
      private static readonly TimeSpan SendTimeout = new TimeSpan(0, 0, 10);
      private const byte MessagePort = 1;
#if PAYLOAD_BCD
      private const string PayloadBcd = "48656c6c6f204c6f526157414e"; // Hello LoRaWAN in BCD
#endif
#if PAYLOAD_BYTES
      private static readonly byte[] PayloadBytes = { 0x48, 0x65, 0x6c, 0x6c, 0x6f, 0x20, 0x4c, 0x6f, 0x52, 0x61, 0x57, 0x41, 0x4e}; // Hello LoRaWAN in bytes
#endif

      public static void Main()
      {
         Result result;

         Debug.WriteLine("devMobile.IoT.Rak811LoRaWanDeviceClient starting");

         Debug.WriteLine($"Ports :{Windows.Devices.SerialCommunication.SerialDevice.GetDeviceSelector()}");

         try
         {
            using ( Rak811LoRaWanDevice device = new Rak811LoRaWanDevice())
            {
               result = device.Initialise(SerialPortId, 9600, SerialParity.None, 8, SerialStopBitCount.One);
               if (result != Result.Success)
               {
                  Debug.WriteLine($"Initialise failed {result}");
                  return;
               }

#if CONFIRMED
               device.OnMessageConfirmation += OnMessageConfirmationHandler;
#endif
               device.OnReceiveMessage += OnReceiveMessageHandler;

               Debug.WriteLine($"{DateTime.UtcNow:hh:mm:ss} Region {Region}");
               result = device.Region(Region);
               if (result != Result.Success)
               {
                  Debug.WriteLine($"Region failed {result}");
                  return;
               }

               Debug.WriteLine($"{DateTime.UtcNow:hh:mm:ss} ADR On");
               result = device.AdrOn();
               if (result != Result.Success)
               {
                  Debug.WriteLine($"ADR on failed {result}");
                  return;
               }

#if CONFIRMED
               Debug.WriteLine($"{DateTime.UtcNow:hh:mm:ss} Confirmed");
               result = device.Confirm(LoRaConfirmType.Confirmed);
               if (result != Result.Success)
               {
                  Debug.WriteLine($"Confirm on failed {result}");
                  return;
               }
#else
               Debug.WriteLine($"{DateTime.UtcNow:hh:mm:ss} Unconfirmed");
               result = device.Confirm(LoRaConfirmType.Unconfirmed);
               if (result != Result.Success)
               {
                  Debug.WriteLine($"Confirm off failed {result}");
                  return;
               }
#endif

#if OTAA
               Debug.WriteLine($"{DateTime.UtcNow:hh:mm:ss} OTAA");
               result = device.OtaaInitialise(DevEui, AppEui, AppKey);
               if (result != Result.Success)
               {
                  Debug.WriteLine($"OTAA Initialise failed {result}");
                  return;
               }
#endif

#if ABP
               Debug.WriteLine($"{DateTime.UtcNow:hh:mm:ss} ABP");
               result = device.AbpInitialise(DevAddress, NwksKey, AppsKey);
               if (result != Result.Success)
               {
                  Debug.WriteLine($"ABP Initialise failed {result}");
                  return;
               }
#endif

               Debug.WriteLine($"{DateTime.UtcNow:hh:mm:ss} Join start Timeout:{JoinTimeOut:hh:mm:ss}");
               result = device.Join(JoinTimeOut);
               if (result != Result.Success)
               {
                  Debug.WriteLine($"Join failed {result}");
                  return;
               }
               Debug.WriteLine($"{DateTime.UtcNow:hh:mm:ss} Join finish");

               while (true)
               {
#if PAYLOAD_BCD
                  Debug.WriteLine($"{DateTime.UtcNow:hh:mm:ss} Send Timeout:{SendTimeout:hh:mm:ss} port:{MessagePort} payload BCD:{PayloadBcd}");
                  result = device.Send(MessagePort, PayloadBcd, SendTimeout);
#endif
#if PAYLOAD_BYTES
                  Debug.WriteLine($"{DateTime.UtcNow:hh:mm:ss} Send Timeout:{SendTimeout:hh:mm:ss} port:{MessagePort} payload Bytes:{BitConverter.ToString(PayloadBytes)}");
                  result = device.Send(MessagePort, PayloadBytes, SendTimeout);
#endif
                  if (result != Result.Success)
                  {
                     Debug.WriteLine($"Send failed {result}");
                  }

                  // if we sleep module too soon response is missed
                  Thread.Sleep(new TimeSpan( 0,0,5));

                  Debug.WriteLine($"{DateTime.UtcNow:hh:mm:ss} Sleep");
                  result = device.Sleep();
                  if (result != Result.Success)
                  {
                     Debug.WriteLine($"Sleep failed {result}");
                     return;
                  }

                  Thread.Sleep(new TimeSpan(0, 5, 0));

                  Debug.WriteLine($"{DateTime.UtcNow:hh:mm:ss} Wakeup");
                  result = device.Wakeup();
                  if (result != Result.Success)
                  {
                     Debug.WriteLine($"Wakeup failed {result}");
                     return;
                  }
               }
            }
         }
         catch (Exception ex)
         {
            Debug.WriteLine(ex.Message);
         }
      }

      static void OnMessageConfirmationHandler(int rssi, int snr)
      {
         Debug.WriteLine($"{DateTime.UtcNow:hh:mm:ss} Send Confirm RSSI:{rssi} SNR:{snr}");
      }

      static void OnReceiveMessageHandler(int port, int rssi, int snr, string payloadBcd)
      {
         byte[] payloadBytes = Rak811LoRaWanDevice.BcdToByes(payloadBcd);

         Debug.WriteLine($"{DateTime.UtcNow:hh:mm:ss} Receive Message RSSI:{rssi} SNR:{snr} Port:{port} Payload:{payloadBcd} PayLoadBytes:{BitConverter.ToString(payloadBytes)}");
      }
   }
}

I have LoRaWAN shields from GobalSat and EmOne on order.

The library works but should be treated as late beta.

nanoFramework RAK811 LoRaWAN library Part7

Now with added callbacks

After building a nanoFramwork library “inspired” by the RakWireless Arduino library(which has some issues) I figured it would be good to refactor the library to be more asynchronous with event handlers for send confirmation (if configured) and received messages.

If the RAK811 module is initialised, and connects to the network successfully, the application sends “48656c6c6f204c6f526157414e” (“hello LoRaWAN”) every 5 minutes.

STM32F691Discovery with EVB plugged into Arduino headers

The code application code now has a lot more compile time options for network configuration and payload format.

//---------------------------------------------------------------------------------
// Copyright (c) June 2020, devMobile Software
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
//     http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
//
//---------------------------------------------------------------------------------
#define ST_STM32F769I_DISCOVERY      // nanoff --target ST_STM32F769I_DISCOVERY --update 
#define PAYLOAD_BCD
//#define PAYLOAD_BYTES
#define OTAA
//#define ABP
#define CONFIRMED
namespace devMobile.IoT.Rak811LoRaWanDeviceClient
{
   using System;
   using System.Threading;
   using System.Diagnostics;
   using Windows.Devices.SerialCommunication;

   using devMobile.IoT.LoRaWan;

   public class Program
   {
#if ST_STM32F769I_DISCOVERY
      private const string SerialPortId = "COM6";
#endif
#if OTAA
      private const string DevEui = "...";
      private const string AppEui = "...";
      private const string AppKey = "...";
#endif
#if ABP
      private const string DevAddress = "...";
      private const string NwksKey = "...";
      private const string AppsKey = "...";
#endif
      private const string Region = "AS923";
      private static readonly TimeSpan JoinTimeOut = new TimeSpan(0, 0, 10);
      private static readonly TimeSpan SendTimeout = new TimeSpan(0, 0, 10);
      private const byte MessagePort = 1;
#if PAYLOAD_BCD
      private const string PayloadBcd = "48656c6c6f204c6f526157414e"; // Hello LoRaWAN in BCD
#endif
#if PAYLOAD_BYTES
      private static readonly byte[] PayloadBytes = { 0x48, 0x65, 0x6c, 0x6c, 0x6f, 0x20, 0x4c, 0x6f, 0x52, 0x61, 0x57, 0x41, 0x4e}; // Hello LoRaWAN in bytes
#endif

      public static void Main()
      {
         Result result;

         Debug.WriteLine("devMobile.IoT.Rak811LoRaWanDeviceClient starting");

         Debug.WriteLine($"Ports :{Windows.Devices.SerialCommunication.SerialDevice.GetDeviceSelector()}");

         try
         {
            using ( Rak811LoRaWanDevice device = new Rak811LoRaWanDevice())
            {
               result = device.Initialise(SerialPortId, 9600, SerialParity.None, 8, SerialStopBitCount.One);
               if (result != Result.Success)
               {
                  Debug.WriteLine($"Initialise failed {result}");
                  return;
               }

#if CONFIRMED
               device.OnMessageConfirmation += OnMessageConfirmationHandler;
#endif
               device.OnReceiveMessage += OnReceiveMessageHandler;

               Debug.WriteLine($"{DateTime.UtcNow:hh:mm:ss} Region {Region}");
               result = device.Region(Region);
               if (result != Result.Success)
               {
                  Debug.WriteLine($"Region failed {result}");
                  return;
               }

               Debug.WriteLine($"{DateTime.UtcNow:hh:mm:ss} ADR On");
               result = device.AdrOn();
               if (result != Result.Success)
               {
                  Debug.WriteLine($"ADR on failed {result}");
                  return;
               }

#if CONFIRMED
               Debug.WriteLine($"{DateTime.UtcNow:hh:mm:ss} Confirmed");
               result = device.Confirm(LoRaConfirmType.Confirmed);
               if (result != Result.Success)
               {
                  Debug.WriteLine($"Confirm on failed {result}");
                  return;
               }
#else
               Debug.WriteLine($"{DateTime.UtcNow:hh:mm:ss} Unconfirmed");
               result = device.Confirm(LoRaConfirmType.Unconfirmed);
               if (result != Result.Success)
               {
                  Debug.WriteLine($"Confirm off failed {result}");
                  return;
               }
#endif

#if OTAA
               Debug.WriteLine($"{DateTime.UtcNow:hh:mm:ss} OTAA");
               result = device.OtaaInitialise(DevEui, AppEui, AppKey);
               if (result != Result.Success)
               {
                  Debug.WriteLine($"OTAA Initialise failed {result}");
                  return;
               }
#endif

#if ABP
               Debug.WriteLine($"{DateTime.UtcNow:hh:mm:ss} ABP");
               result = device.AbpInitialise(DevAddress, NwksKey, AppsKey);
               if (result != Result.Success)
               {
                  Debug.WriteLine($"ABP Initialise failed {result}");
                  return;
               }
#endif

               Debug.WriteLine($"{DateTime.UtcNow:hh:mm:ss} Join start Timeout:{JoinTimeOut:hh:mm:ss}");
               result = device.Join(JoinTimeOut);
               if (result != Result.Success)
               {
                  Debug.WriteLine($"Join failed {result}");
                  return;
               }
               Debug.WriteLine($"{DateTime.UtcNow:hh:mm:ss} Join finish");

               while (true)
               {
#if PAYLOAD_BCD
                  Debug.WriteLine($"{DateTime.UtcNow:hh:mm:ss} Send Timeout:{SendTimeout:hh:mm:ss} port:{MessagePort} payload BCD:{PayloadBcd}");
                  result = device.Send(MessagePort, PayloadBcd, SendTimeout);
#endif
#if PAYLOAD_BYTES
                  Debug.WriteLine($"{DateTime.UtcNow:hh:mm:ss} Send Timeout:{SendTimeout:hh:mm:ss} port:{MessagePort} payload Bytes:{BitConverter.ToString(PayloadBytes)}");
                  result = device.Send(MessagePort, PayloadBytes, SendTimeout);
#endif
                  if (result != Result.Success)
                  {
                     Debug.WriteLine($"Send failed {result}");
                  }

                  // if we sleep module too soon response is missed
                  Thread.Sleep(new TimeSpan( 0,0,5));

                  Debug.WriteLine($"{DateTime.UtcNow:hh:mm:ss} Sleep");
                  result = device.Sleep();
                  if (result != Result.Success)
                  {
                     Debug.WriteLine($"Sleep failed {result}");
                     return;
                  }

                  Thread.Sleep(new TimeSpan(0, 5, 0));

                  Debug.WriteLine($"{DateTime.UtcNow:hh:mm:ss} Wakeup");
                  result = device.Wakeup();
                  if (result != Result.Success)
                  {
                     Debug.WriteLine($"Wakeup failed {result}");
                     return;
                  }
               }
            }
         }
         catch (Exception ex)
         {
            Debug.WriteLine(ex.Message);
         }
      }

      static void OnMessageConfirmationHandler(int rssi, int snr)
      {
         Debug.WriteLine($"{DateTime.UtcNow:hh:mm:ss} Send Confirm RSSI:{rssi} SNR:{snr}");
      }

      static void OnReceiveMessageHandler(int port, int rssi, int snr, string payloadBcd)
      {
         byte[] payloadBytes = Rak811LoRaWanDevice.BcdToByes(payloadBcd);

         Debug.WriteLine($"{DateTime.UtcNow:hh:mm:ss} Receive Message RSSI:{rssi} SNR:{snr} Port:{port} Payload:{payloadBcd} PayLoadBytes:{BitConverter.ToString(payloadBytes)}");
      }
   }
}

The debugging output with the Rak811LoRaWanDevice class diagnostics off

The thread '<No Name>' (0x2) has exited with code 0 (0x0).
devMobile.IoT.Rak811LoRaWanDeviceClient starting
Ports :COM5,COM6
12:00:51 Region AS923
12:00:51 ADR On
12:00:51 Confirmed
12:00:52 OTAA
12:00:52 Join start Timeout:00:00:10
12:00:59 Join finish
12:00:59 Send Timeout:00:00:10 port:1 payload BCD:48656c6c6f204c6f526157414e
12:01:02 Send Confirm RSSI:-79 SNR:9
12:01:07 Sleep
12:06:07 Wakeup
12:06:07 Send Timeout:00:00:10 port:1 payload BCD:48656c6c6f204c6f526157414e
12:06:08 Send Confirm RSSI:-65 SNR:8
12:06:13 Sleep
12:11:13 Wakeup
12:11:13 Send Timeout:00:00:10 port:1 payload BCD:48656c6c6f204c6f526157414e
12:11:15 Send Confirm RSSI:-60 SNR:7
12:11:15 Receive Message RSSI:-60 SNR:7 Port:5 Payload:48656c6c6f PayLoadBytes:48-65-6C-6C-6F
12:11:20 Sleep
TTN OTAA Connection + RX&TX

Some commands are quite quick to respond e.g. setting the Region, Sleep, and Wakeup. Others, take quite a while e.g. Join, Send, WorkMode so they have separate timeout configurations.

The code is approaching beat and I’ll be testing and fixing bugs for the next couple of days.

nanoFramework RAK811 LoRaWAN library Part6

Inspired by the Arduino Library

After successful proof of concept projects I have build a nanoFramwork library “inspired” by the RakWireless Arduino library.

The initial version only supports my RAK811 LPWAN Evaluation Board(EVB) and STM32F691DISCOVERY based test rig It handles failures, displays error codes/messages, but doesn’t handle all timeouts.

If the RAK811 module is initialised, then connects to the network successfully, the application sends “48656c6c6f204c6f526157414e” (“hello LoRaWAN”) every 20 seconds.

STM32F691Discovery with EVB plugged into Arduino headers

The code application code is now a lot smaller & simpler

   public class Program
   {
#if ST_STM32F769I_DISCOVERY
      private const string SerialPortId = "COM6";
#endif
#if OTAA
      private const string DevEui = "...";
      private const string AppEui = "...";
      private const string AppKey = "...";
#endif
#if ABP
      private const string devAddress = "...";
      private const string nwksKey = "...";
      private const string appsKey = "...";
#endif
      private const byte MessagePort = 1;
      private const string Payload = "48656c6c6f204c6f526157414e"; // Hello LoRaWAN

      public static void Main()
      {
         Result result;

         Debug.WriteLine(" devMobile.IoT.Rak811LoRaWanDeviceClient starting");

         Debug.WriteLine(Windows.Devices.SerialCommunication.SerialDevice.GetDeviceSelector());

         try
         {
            using ( Rak811LoRaWanDevice device = new Rak811LoRaWanDevice())
            {
               result = device.Initialise(SerialPortId, SerialParity.None, 8, SerialStopBitCount.One);
               if (result != Result.Success)
               {
                  Debug.WriteLine($"Initialise failed {result}");
                  return;
               }

               result = device.Region("AS923");
               if (result != Result.Success)
               {
                  Debug.WriteLine($"Region failed {result}");
                  return;
               }

#if OTAA
               result = device.OtaaInitialise(DevEui, AppEui, AppKey);
               if (result != Result.Success)
               {
                  Debug.WriteLine($"OTAA Initialise failed {result}");
                  return;
               }
#endif

#if ABP
               result = device.AbpInitialise(devAddress, nwksKey, appsKey);
               if (result != Result.Success)
               {
                  Debug.WriteLine($"ABP Initialise failed {result}");
                  return;
               }
#endif

               result = device.Join(new TimeSpan(0,0,10));
               if (result != Result.Success)
               {
                  Debug.WriteLine($"Join failed {result}");
                  return;
               }

               while (true)
               {
                  result = device.Send(MessagePort, Payload);
                  if (result != Result.Success)
                  {
                     Debug.WriteLine($"Send failed {result}");
                  }

                  result = device.Sleep();
                  if (result != Result.Success)
                  {
                     Debug.WriteLine($"Sleep failed {result}");
                     return;
                  }

                  Thread.Sleep(20000);

                  result = device.Wakeup();
                  if (result != Result.Success)
                  {
                     Debug.WriteLine($"Wakeup failed {result}");
                     return;
                  }
               }
            }
         }
         catch (Exception ex)
         {
            Debug.WriteLine(ex.Message);
         }
      }
   }

I compared the debugging output with confirmations off

The thread '<No Name>' (0x2) has exited with code 0 (0x0).
 devMobile.IoT.Rak811LoRaWanDeviceClient starting
COM5,COM6
01:11:13 lora:work_mode
TX: send 32 bytes 32 via COM6
RX 01:11:14:UART1 work mode: RUI_UART_NORAMAL
Current work_mode:LoRaWAN, join_mode:OTAA, Class: A
Initialization OK 

01:11:15 lora:region
TX: send 33 bytes 33 via COM6
RX 01:11:16:OK 

01:11:16 lora:join_mode
TX: send 32 bytes 32 via COM6
RX 01:11:17:OK 

01:11:18 lora:dev_eui
TX: send 45 bytes 45 via COM6
RX 01:11:19:OK 

01:11:19 lora:app_eui
TX: send 45 bytes 45 via COM6
RX 01:11:20:OK 

01:11:21 lora:app_key
TX: send 61 bytes 61 via COM6
RX 01:11:22:OK 

01:11:22 join
TX: send 9 bytes 9 via COM6
RX 01:11:29:OK Join Success

TX: send 43 bytes to output stream.
TX: 43 bytes via COM6
TX: send 43 bytes to output stream.
TX: 43 bytes via COM6
RX :OK 

TX: send 43 bytes to output stream.
TX: 43 bytes via COM6
RX :OK 
at+recv=1,-54,9,5:48656c6c6f

TX: send 43 bytes to output stream.
TX: 43 bytes via COM6

TX: send 43 bytes to output stream.
TX: 43 bytes via COM6
RX :OK 
at+recv=2,-51,7,5:48656c6c6f

TX: send 43 bytes to output stream.
TX: 43 bytes via COM6

Then with confirmations on (note the at+recv=0,-59,7,0) and received messages (at+recv=23,-53,8,5:48656c6c6f)

devMobile.IoT.Rak811LoRaWanDeviceClient starting
COM5,COM6
01:20:54 lora:work_mode
TX: send 32 bytes 32 via COM6
RX 01:20:56:UART1 work mode: RUI_UART_NORAMAL
Current work_mode:LoRaWAN, join_mode:OTAA, Class: A
Initialization OK 

01:20:56 lora:region
TX: send 33 bytes 33 via COM6
RX 01:20:57:OK 

01:20:58 lora:join_mode
TX: send 32 bytes 32 via COM6
RX 01:20:59:OK 

01:20:59 lora:dev_eui
TX: send 45 bytes 45 via COM6
RX 01:21:00:OK 

01:21:01 lora:app_eui
TX: send 45 bytes 45 via COM6
RX 01:21:02:OK 

01:21:02 lora:app_key
TX: send 61 bytes 61 via COM6
RX 01:21:03:OK 

01:21:04 join
TX: send 9 bytes 9 via COM6
RX 01:21:11:OK Join Success

01:21:11 lora:confirm
TX: send 30 bytes 30 via COM6
RX 01:21:12:OK 

TX: send 43 bytes to output stream.
TX: 43 bytes via COM6
TX: send 43 bytes to output stream.
TX: 43 bytes via COM6
TX: send 43 bytes to output stream.
TX: 43 bytes via COM6
RX :OK 
at+recv=23,-53,8,5:48656c6c6f

TX: send 43 bytes to output stream.
TX: 43 bytes via COM6

TX: send 43 bytes to output stream.
TX: 43 bytes via COM6
RX :OK 
at+recv=0,-59,7,0

In the Visual Studio 2019 debug output I could see the responses to the AT Commands and especially the lack of handling of downlink messages and confirmations from the network.

The next step is to implement timeouts for when operations fail or the module doesn’t respond. Then extend the code to support the receiving of messages as a class A device (missing for the RAK arduino library). I wonder how this will work for when the module is configured as a class C device which can receive messages at any time.

Some commands are quite quick to respond e.g. setting the Region, Sleep, and Wakeup so are most probably ok running synchronously. Other commands can take quite a while e.g. Join, Send, WorkMode so maybe these need to be asynchronous (along with the receiving of confirmations and messages ).

The code is not suitable for production but it confirmed my new approach worked.

nanoFramework RAK811 LoRaWAN library Part5

Nasty ABP connect

After a successful Over The Air Activation(OTAA) with my RAK811 LPWAN Evaluation Board(EVB) and STM32F691DISCOVERY based test rig. I figured for completeness an Activation by Personalization (ABP) would be a good.

My ABP implementation is based on my OTAA one so is pretty “nasty”. Again, I assumed that there would be no timeouts or failures and I only send one message BCD “48656c6c6f204c6f526157414e” (“hello LoRaWAN”) every 20 seconds.

STM32F691Discovery with EVB plugged into Arduino headers

I created a new ABP device

Things Network ABP configuration

Then I configured the RAK811 module for LoRaWAN

// Set the Working mode to LoRaWAN
bytesWritten = outputDataWriter.WriteString("at+set_config=lora:work_mode:0rn");
Debug.WriteLine($"TX: work_mode {outputDataWriter.UnstoredBufferLength} bytes to output stream.");
txByteCount = outputDataWriter.Store();
Debug.WriteLine($"TX: {txByteCount} bytes via {serialDevice.PortName}");

// Read the response
bytesRead = inputDataReader.Load(128);
if (bytesRead > 0)
{
   string response = inputDataReader.ReadString(bytesRead);
   Debug.WriteLine($"RX sync:{response}");
}

Then sequentially stepped through the necessary configuration to join the The Things Network(TTN) network

// Set the JoinMode to ABP
bytesWritten = outputDataWriter.WriteString($"at+set_config=lora:join_mode:1\r\n");
Debug.WriteLine($"TX: join_mode {outputDataWriter.UnstoredBufferLength} bytes to output stream.");
txByteCount = outputDataWriter.Store();
Debug.WriteLine($"TX: {txByteCount} bytes via {serialDevice.PortName}");

// Read the response
bytesRead = inputDataReader.Load(128);
if (bytesRead > 0)
{
   String response = inputDataReader.ReadString(bytesRead);
   Debug.WriteLine($"RX :{response}");
}

// Set the device address
bytesWritten = outputDataWriter.WriteString($"at+set_config=lora:dev_addr:{devAddress}\r\n");
Debug.WriteLine($"TX: dev_addr {outputDataWriter.UnstoredBufferLength} bytes to output stream.");
txByteCount = outputDataWriter.Store();
Debug.WriteLine($"TX: {txByteCount} bytes via {serialDevice.PortName}");

// Read the response
bytesRead = inputDataReader.Load(128);
if (bytesRead > 0)
   {
   String response = inputDataReader.ReadString(bytesRead);
   Debug.WriteLine($"RX :{response}");
   }
...

After making a few fixes to my code and tweaking some settings I could see data in the TTN Console.

ABP Device data uplink

The code is not suitable for production but it confirmed my software and hardware configuration worked.

In the Visual Studio 2019 debug output I could see the AT Command responses from were getting truncated in odd ways so I need to be careful how they are processed.

The thread '<No Name>' (0x2) has exited with code 0 (0x0).
devMobile.IoT.Rak811.NetworkJoinABP starting
COM5,COM6
TX: work_mode 32 bytes to output stream.
TX: 32 bytes via COM6
RX :UART1 work mode: RUI_UART_NORAMAL
Current work_mode:LoRaWAN, join_mode:ABP, Class: A
Initialization OK 

TX: region 33 bytes to output stream.
TX: 33 bytes via COM6
RX :OK 

TX: join_mode 32 bytes to output stream.
TX: 32 bytes via COM6
RX :OK 

TX: dev_addr 38 bytes to output stream.
TX: 38 bytes via COM6
RX :OK 

TX: nwks_key 62 bytes to output stream.
TX: 62 bytes via COM6
RX :OK 

TX: apps_key 62 bytes to output stream.
TX: 62 bytes via COM6
RX :OK 

TX: confirm 30 bytes to output stream.
TX: 30 bytes via COM6
RX :OK 

TX: join 9 bytes to output stream.
TX: 9 bytes via COM6
TX: send 43 bytes to output stream.
TX: 43 bytes via COM6
TX: send 43 bytes to output stream.
TX: 43 bytes via COM6
RX :OK Jo
TX: send 43 bytes to output stream.
TX: 43 bytes via COM6
RX :in Su
TX: send 43 bytes to output stream.
TX: 43 bytes via COM6
RX :ccess
TX: send 43 bytes to output stream.
TX: 43 bytes via COM6
RX :
OK 
TX: send 43 bytes to output stream.
TX: 43 bytes via COM6
RX :
OK 

The next step is to get rework the code to process responses to the AT commands in a smarter way and extract error codes when an operation fails.

nanoFramework RAK811 LoRaWAN library Part4

Nasty OTAA connect

After getting basic connectivity for my RAK811 LPWAN Evaluation Board(EVB) and STM32F691DISCOVERY test rig sorted. I wanted to see if I could get the device connected to The Things Network(TTN) via the RAK7246G LPWAN Developer Gateway which was on my desk. I had got the EVB configuration sorted with an Arduino Uno R3 device so I was confident it should work.

STM32F691Discovery with EVB plugged into Arduino headers

My Over the Air Activation(OTAA) implementation is pretty “nasty” I assumed that there would be no timeouts or failures and I only send one BCD message “48656c6c6f204c6f526157414e” which is “hello LoRaWAN”

I configured the RAK811 module for LoRaWAN

// Set the Working mode to LoRaWAN
bytesWritten = outputDataWriter.WriteString("at+set_config=lora:work_mode:0\r\n");
Debug.WriteLine($"TX: work_mode {outputDataWriter.UnstoredBufferLength} bytes to output stream.");
txByteCount = outputDataWriter.Store();
Debug.WriteLine($"TX: {txByteCount} bytes via {serialDevice.PortName}");

// Read the response
bytesRead = inputDataReader.Load(128);
if (bytesRead > 0)
{
   string response = inputDataReader.ReadString(bytesRead);
   Debug.WriteLine($"RX sync:{response}");
}

Then just sequentially stepped through the necessary configuration to join the TTN network

// Set the Region to AS923
bytesWritten = outputDataWriter.WriteString("at+set_config=lora:region:AS923\r\n");
Debug.WriteLine($"TX: region {outputDataWriter.UnstoredBufferLength} bytes to output stream.");
txByteCount = outputDataWriter.Store();
Debug.WriteLine($"TX: {txByteCount} bytes via {serialDevice.PortName}");

// Read the response
bytesRead = inputDataReader.Load(128);
if (bytesRead > 0)
{
   String response = inputDataReader.ReadString(bytesRead);
   Debug.WriteLine($"RX sync:{response}");
}

// Set the JoinMode
bytesWritten = outputDataWriter.WriteString($"at+set_config=lora:join_mode:0\r\n");
Debug.WriteLine($"TX: join_mode {outputDataWriter.UnstoredBufferLength} bytes to output stream.");
txByteCount = outputDataWriter.Store();
Debug.WriteLine($"TX: {txByteCount} bytes via {serialDevice.PortName}");

// Read the response
bytesRead = inputDataReader.Load(128);
if (bytesRead > 0)
{
   String response = inputDataReader.ReadString(bytesRead);
   Debug.WriteLine($"RX sync:{response}");
}

// OTAA set the devEUI
bytesWritten = outputDataWriter.WriteString($"at+set_config=lora:dev_eui:{devEui}\r\n");
Debug.WriteLine($"TX: dev_eui {outputDataWriter.UnstoredBufferLength} bytes to output stream.");
txByteCount = outputDataWriter.Store();
Debug.WriteLine($"TX: {txByteCount} bytes via {serialDevice.PortName}");

// Read the response
bytesRead = inputDataReader.Load(128);
if (bytesRead > 0)
{
   String response = inputDataReader.ReadString(bytesRead);
   Debug.WriteLine($"RX sync:{response}");
}
...

The code is not suitable for production but it confirmed my software and hardware configuration worked.

The thread '<No Name>' (0x2) has exited with code 0 (0x0).
devMobile.IoT.Rak811.NetworkJoinOTAA starting
COM5,COM6
TX: work_mode 32 bytes to output stream.
TX: 32 bytes via COM6
RX sync:UART1 work mode: RUI_UART_NORAMAL
Current work_mode:LoRaWAN, join_mode:OTAA, Class: A
Initialization OK 

TX: region 33 bytes to output stream.
TX: 33 bytes via COM6
RX sync:OK 

TX: join_mode 32 bytes to output stream.
TX: 32 bytes via COM6
RX sync:OK 

TX: dev_eui 45 bytes to output stream.
TX: 45 bytes via COM6
RX sync:OK 

TX: app_eui 45 bytes to output stream.
TX: 45 bytes via COM6
RX sync:OK 

TX: app_key 61 bytes to output stream.
TX: 61 bytes via COM6
RX sync:OK 

TX: confirm 30 bytes to output stream.
TX: 30 bytes via COM6
RX sync:OK 

TX: join 9 bytes to output stream.
TX: 9 bytes via COM6
RX sync:
RX sync:
RX sync:
RX sync:
RX sync:OK Join Success

TX: send 43 bytes to output stream.
TX: 43 bytes via COM6
TX: send 43 bytes to output stream.
TX: 43 bytes via COM6
RX sync:OK 
at+recv=0,-59,9,0

In the Visual Studio 2019 debug out put I could see messages getting sent and then after a short delay they were visible in the TTN console.

I then modified the confirmed flag and in the TTN console I could see how they were processed differently.

Confirmed messages
Unconfirmed messages

I could receive messages but as the RAK 811 module can be configured to be a Class C device there didn’t appear to be a way to receive a message without sending one which seemed a bit odd.

The next step is to get Authentication By Personalisation(ABP) working.