.NET nanoFramework RAK4200 LoRaWAN library OTAA Join

When I first tried Over The Air Activation(OTAA) to connect to The Things Network(TTN) with my RAKwireless RAK4200 module it didn’t work. I built another test harness with an FTDI module so I could send AT commands with the RAK Serial Port Tool to my RAK4200 module.

RAK4200 -> FTDI -? PC test harness

The default baud rate is 115200 but I sent “at+set_config=device:uart:1:9600” to the RAK4200 module.

RAK Serial Port Tool initiating at+join command

With the RAK Serial Port Tool I could get the RAK4200 connected to TTN and send unconfirmed messages. The sequence of commands I used was

at+set_config=lora:join_mode:0
at+set_config=lora:class:0
at+set_config=lora:region:AS923
at+set_config=lora:dev_eui:XXXX
at+set_config=lora:app_eui:XXXX
at+set_config=lora:app_key:XXXX
at+set_config=device:restart
at+join
at+send=lora:2:48656c6c6f204c6f526157414e

I then returned to my STM32F769I Discovery, RAK4200 Breakoutboard, Seeedstudio Grove Base Shield for Arduino and a Seeedstudio Grove-4 pin Female Jumper to Grove 4 pin Conversion Cable based test harness.

RAK4200, STM32F769I Discovery test harness

I modified the NetworkJoinOTAA sample(based on the asynchronous version of BreakOutSerial) to send the same sequence of AT commands and display the responses.

namespace devMobile.IoT.LoRaWAN.nanoFramework.RAK4200
{
   using System;
	using System.Diagnostics;
   using System.IO.Ports;
   using System.Threading;

   public class Program
	{
      private const string SerialPortId = "COM6";
      private const string DevEui = "...";
      private const string AppEui = "...";
      private const string AppKey = "...";
      private const byte MessagePort = 1;
      private const string Payload = "48656c6c6f204c6f526157414e"; // Hello LoRaWAN

      public static void Main()
      {
         string response;

         Debug.WriteLine("devMobile.IoT.Rak4200.NetworkJoinOTAA starting");

         Debug.Write("Ports:");
         foreach (string port in SerialPort.GetPortNames())
         {
            Debug.Write($" {port}");
         }
         Debug.WriteLine("");

         try
         {
            using (SerialPort serialDevice = new SerialPort(SerialPortId))
            {
               // set parameters
               serialDevice.BaudRate = 9600;
               //_SerialPort.BaudRate = 115200;
               serialDevice.Parity = Parity.None;
               serialDevice.StopBits = StopBits.One;
               serialDevice.Handshake = Handshake.None;
               serialDevice.DataBits = 8;

               serialDevice.ReadTimeout = 10000;

               serialDevice.NewLine = "\r\n";

               serialDevice.DataReceived += SerialDevice_DataReceived;

               serialDevice.Open();

               serialDevice.WatchChar = '\n';

               // clear out the RX buffer
               serialDevice.ReadExisting();
               response = serialDevice.ReadExisting();
               Debug.WriteLine($"Response :{response.Trim()} bytes:{response.Length}");
               Thread.Sleep(500);

               // Set the Working mode to LoRaWAN
               Console.WriteLine("lora:work_mode:0");
               serialDevice.WriteLine("at+set_config=lora:work_mode:0");

               // Set the JoinMode
               Console.WriteLine("lora:join_mode");
               serialDevice.WriteLine("at+set_config=lora:join_mode:0");
               Thread.Sleep(500);

               // Set the Class
               Console.WriteLine("lora:class");
               serialDevice.WriteLine("at+set_config=lora:class:0");
               Thread.Sleep(500);

               // Set the Region to AS923
               Console.WriteLine("lora:region:AS923");
               serialDevice.WriteLine("at+set_config=lora:region:AS923");
               Thread.Sleep(500);

               // Set the devEUI
               Console.WriteLine("lora:dev_eui:{DevEui}");
               serialDevice.WriteLine($"at+set_config=lora:dev_eui:{DevEui}");
               Thread.Sleep(500);

               // Set the appEUI
               Console.WriteLine("lora:app_eui:{AppEui}");
               serialDevice.WriteLine($"at+set_config=lora:app_eui:{AppEui}");
               Thread.Sleep(500);

               // Set the appKey
               Console.WriteLine("lora:app_key:{AppKey}");
               serialDevice.WriteLine($"at+set_config=lora:app_key:{AppKey}");
               Thread.Sleep(500);

               // Set the Confirm flag
               Console.WriteLine("lora:confirm:0");
               serialDevice.WriteLine("at+set_config=lora:confirm:0");
               Thread.Sleep(500);

               // Reset the device
               Console.WriteLine("device:restart");
               serialDevice.WriteLine($"at+set_config=device:restart");
               Thread.Sleep(10000);

               // Join the network
               Console.WriteLine("at+join");
               serialDevice.WriteLine("at+join");
               Thread.Sleep(10000);

               while (true)
               {
                  // Send the BCD messages
                  Console.WriteLine("lora:{MessagePort}:{Payload}");
                  serialDevice.WriteLine($"at+send=lora:{MessagePort}:{Payload}");

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

      private static void SerialDevice_DataReceived(object sender, SerialDataReceivedEventArgs e)
      {
         SerialPort serialPort = (SerialPort)sender;
         string response;

         switch (e.EventType)
         {
            case SerialData.Chars:
               break;

            case SerialData.WatchChar:
               response = serialPort.ReadExisting();
               Debug.Write(response);
               break;
            default:
               Debug.Assert(false, $"e.EventType {e.EventType} unknown");
               break;
         }
      }
   }
}

The NetworkJoinOTAA application assumes that all of the AT commands succeed

Visual Studio Output windows displaying connection process and a D2C message
TTN Console live data tab connection process
TTN Console live messaging tab C2D message

I need to find a way to set the RAK4200 back to factory settings so I can figure out what settings are persisted by the “at+set_config=device:restart” and which ones need to be set every time the application is run.

.NET nanoFramework RAK4200 LoRaWAN library basic connectivity

Over the last couple of evenings I have been working on a .NET nanoFramework library for the RAKwireless RAK4200 module using a STM32F769I Discovery, RAK4200 Breakoutboard, Seeedstudio Grove Base Shield for Arduino and a Seeedstudio Grove-4 pin Female Jumper to Grove 4 pin Conversion Cable.

RAK 4200 STM32F769I Discovery testrig

My sample code has compile time options for synchronous and asynchronous operation.

//---------------------------------------------------------------------------------
// Copyright (c) May 2022, 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 SERIAL_SYNC_READ
#define SERIAL_ASYNC_READ
//#define SERIAL_THREADED_READ
#define ST_STM32F769I_DISCOVERY      // nanoff --target ST_STM32F769I_DISCOVERY --update 
...

namespace devMobile.IoT.LoRaWAN.nanoFramework.RAK4200
{
	using System;
	using System.Diagnostics;
	using System.IO.Ports;
	using System.Threading;

	public class Program
	{
		private static SerialPort _SerialPort;
#if SERIAL_THREADED_READ
		private static Boolean _Continue = true;
#endif
...
#if ST_STM32F769I_DISCOVERY
		private const string SerialPortId = "COM6";
#endif

		public static void Main()
		{
#if SERIAL_THREADED_READ
			Thread readThread = new Thread(SerialPortProcessor);
#endif

			Debug.WriteLine("devMobile.IoT.LoRaWAN.nanoFramework.RAK4200 BreakoutSerial starting");

			Debug.Write("Ports:");
			foreach (string port in SerialPort.GetPortNames())
			{
				Debug.Write($" {port}");
			}
			Debug.WriteLine("");

			try
			{
				// set GPIO functions for COM2 (this is UART1 on ESP32)
#if ESP32_WROOM
				Configuration.SetPinFunction(Gpio.IO04, DeviceFunction.COM2_TX);
            Configuration.SetPinFunction(Gpio.IO05, DeviceFunction.COM2_RX);
#endif

				_SerialPort = new SerialPort(SerialPortId);

				// set parameters
				_SerialPort.BaudRate = 115200;
				_SerialPort.Parity = Parity.None;
				_SerialPort.DataBits = 8;
				_SerialPort.StopBits = StopBits.One;
				_SerialPort.Handshake = Handshake.None;

				_SerialPort.ReadTimeout = 1000;
				_SerialPort.NewLine = "\r\n";

				//_SerialPort.WatchChar = '\n'; // May 2022 WatchChar event didn't fire github issue https://github.com/nanoframework/Home/issues/1035

				_SerialPort.Open();

				_SerialPort.WatchChar = '\n';

#if SERIAL_THREADED_READ
				readThread.Start();
#endif

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

				while (true)
				{
					string atCommand = "at+version";
					Debug.WriteLine($"TX:{atCommand} bytes:{atCommand.Length}");
					_SerialPort.WriteLine(atCommand);

#if SERIAL_SYNC_READ
					// Read the response
					string response = _SerialPort.ReadLine();
					Debug.WriteLine($"RX:{response.Trim()} bytes:{response.Length}");
#endif
					Thread.Sleep(15000);
				}
			}
			catch (Exception ex)
			{
				Debug.WriteLine(ex.Message);
			}
		}

#if SERIAL_ASYNC_READ
		private static void SerialDevice_DataReceived(object sender, SerialDataReceivedEventArgs e)
		{
			SerialPort serialPort = (SerialPort)sender;
			string response;

			switch (e.EventType)
			{
				case SerialData.Chars:
					/*
					response = serialPort.ReadExisting();

					if ( response.Length>0)
					{ 
						Debug.WriteLine($"RX Char:{response.Trim()} bytes:{response.Length}");
					}
					*/
					break;
				case SerialData.WatchChar:
					response = serialPort.ReadExisting();

					if (response.Length > 0)
					{
						Debug.WriteLine($"RX WatchChar :{response.Trim()} bytes:{response.Length}");
					}
					break;
				default:
					Debug.Assert(false, $"e.EventType {e.EventType} unknown");
					break;
			}
		}
#endif

#if SERIAL_THREADED_READ
		public static void SerialPortProcessor()
		{
			string response;

			while (_Continue)
			{
				try
				{
					response = _SerialPort.ReadLine();
					//response = _SerialPort.ReadExisting();
					Console.WriteLine($"RX:{response} bytes:{response.Length}");
				}
				catch (TimeoutException ex) 
				{
					Console.WriteLine($"Timeout:{ex.Message}");
				}
			}
		}
#endif
	}
}

When I requested the RAK4200 Module version information with “at+version” the response was a single line (unlike the RAK3172 version where the response is three lines). The asynchronous version of the application displays character(s) as they arrive so a response could be split across multiple SerialDataReceived events.

Asynchronous approach with multiple SerialData.Chars events

With the initial version of SerialDevice_DataReceived event handler the firmware version response was available in the first SerialData.Chars event, then a SerialData.Chars event fired for each character

Asynchronous approach with SerialData.Chars events with an empty buffer removed

I also noticed that the “SerialData.WatchChar” event was not firing. After some experimentation I found that if I set the SerialPort.WatchChar before opening the serial port there were no events, but if I set SerialPort.WatchChar after opening the serial port events were fired as expected(See note re github issue in code)

Asynchronous approach with SerialPort.WatchChar work as expected

I also implemented a threaded approach for reading characters from the serial port. Normally using Exceptions for flow control is not a good idea but in this case I can’t see an alternative approach.

Thread approach SerialPort.ReadLine() timeouts

The RAK4200 Module defaults 115200 baud which seems overkill considering the throughput of a LoRaWAN link.

RAK3172LoRaWAN-NetCore on Github

The source code for a late beta version of my .Net Core C# library for RAK3172 modules is now available on GitHub.

Using SerialDataReceivedEventHandler was causing memory management problems so the core command processor now runs in its own Thread.(Though I worry about the continuous System.TimeoutExceptions)

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/hexadecimal messages.

//---------------------------------------------------------------------------------
// Copyright (c) September 2021, 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.
//
// Must have one of following options defined in the project\build definitions
//    PAYLOAD_BCD or PAYLOAD_BYTES
//    OTAA or ABP
//
// Optional definitions
//    CONFIRMED For confirmed messages
//		DEVEUI_SET
//
//---------------------------------------------------------------------------------
namespace devMobile.IoT.LoRaWAN.NetCore.RAK3172
{
	using System;
	using System.IO.Ports;
	using System.Threading;


	public class Program
	{
		private const string SerialPortId = "/dev/ttyS0";
		private const LoRaClass Class = LoRaClass.A;
		private const string Band = "8-1";
		private const byte MessagePort = 10;
		private static readonly TimeSpan MessageSendTimerDue = new TimeSpan(0, 0, 15);
		private static readonly TimeSpan MessageSendTimerPeriod = new TimeSpan(0, 5, 0);
		private static Timer MessageSendTimer ;
		private const int JoinRetryAttempts = 2;
		private const int JoinRetryIntervalSeconds = 10;
#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;

			Console.WriteLine("devMobile.IoT.LoRaWAN.NetCore.RAK3172 RAK3712LoRaWANDeviceClient starting");

			Console.WriteLine($"Serial ports:{String.Join(",", SerialPort.GetPortNames())}");

			try
			{
				using (Rak3172LoRaWanDevice device = new Rak3172LoRaWanDevice())
				{
					result = device.Initialise(SerialPortId, 9600, Parity.None, 8, StopBits.One);
					if (result != Result.Success)
					{
						Console.WriteLine($"Initialise failed {result}");
						return;
					}

					MessageSendTimer = new Timer(SendMessageTimerCallback, device,Timeout.Infinite, Timeout.Infinite);

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

#if DEVEUI_SET
					Console.WriteLine($"{DateTime.UtcNow:hh:mm:ss} DevEUI {Config.devEui}");
					result = device.DeviceEui(Config.devEui);
					if (result != Result.Success)
					{
						Console.WriteLine($"DevEUI failed {result}");
						return;
					}
#endif

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

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

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

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

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

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

					Console.WriteLine($"{DateTime.UtcNow:hh:mm:ss} Join start");
					result = device.Join(JoinRetryAttempts, JoinRetryIntervalSeconds);
					if (result != Result.Success)
					{
						Console.WriteLine($"Join failed {result}");
						return;
					}
					Console.WriteLine($"{DateTime.UtcNow:hh:mm:ss} Join started");

					Thread.Sleep(Timeout.Infinite);
				}
			}
			catch (Exception ex)
			{
				Console.WriteLine(ex.Message);
			}
		}

		private static void OnJoinCompletionHandler(bool result)
		{
			Console.WriteLine($"{DateTime.UtcNow:hh:mm:ss} Join finished:{result}");

			if (result)
			{ 
				MessageSendTimer.Change(MessageSendTimerDue, MessageSendTimerPeriod);
			}
		}

		private static void SendMessageTimerCallback(object state)
		{
			Rak3172LoRaWanDevice device = (Rak3172LoRaWanDevice)state;

#if PAYLOAD_BCD
			Console.WriteLine($"{DateTime.UtcNow:hh:mm:ss} port:{MessagePort} payload BCD:{PayloadBcd}");
			Result result = device.Send(MessagePort, PayloadBcd );
#endif
#if PAYLOAD_BYTES
			Console.WriteLine($"{DateTime.UtcNow:hh:mm:ss} port:{MessagePort} payload bytes:{Rak3172LoRaWanDevice.BytesToBcd(PayloadBytes)}");
         Result result = device.Send(MessagePort, PayloadBytes);
#endif
			if (result != Result.Success)
			{
				Console.WriteLine($"Send failed {result}");
			}
		}

#if CONFIRMED
		private static void OnMessageConfirmationHandler()
      {
			Console.WriteLine($"{DateTime.UtcNow:hh:mm:ss} Send successful");
		}
#endif

		private static void OnReceiveMessageHandler(byte port, int rssi, int snr, string payload)
		{
			byte[] payloadBytes = Rak3172LoRaWanDevice.HexToByes(payload); // Done this way so both conversion methods tested

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

I have added XML Documentation comments which will need some rework, after I have “soak tested” the code for at least a week.

I have also added a method so the DevEUI can be set (intended for use after device firmware has been updated), fixed up my mistake with Binary Coded Decimal(BCD) vs. Hexadecimal strings.

I will also go back and apply the “learnings” from this refactoring to my other LoRaWAN module and platform libraries

.NET Core RAK3172 LoRaWAN library Part1

Basic connectivity

Over the weekend I have been working on a .NET Core C# library for the RAKwireless RAK3172 module using a RAK3172S breakout board, Seeedstudio Grove Base Hat for Raspberry PI and a Seeedstudio Grove-4 pin Female Jumper to Grove 4 pin Conversion Cable.

Raspberry Pi3 with Grove Base Hat and RAK3172 Breakout (using UART2)

The RaspberryPI OS is a bit more strict than the other devices I use about port access. To allow my .Net Core application to access a serial port I connected to the device with ExtraPutty, then ran the RaspberyPI configuration tool, from the command prompt with “sudo raspi-config”

RaspberyPI OS Software Configuration tool mains screen
RaspberryPI OS IO Serial Port configuration
Raspberry PI OS disabling remote serial login shell
RaspberryPI OS enabling serial port access

Once serial port access was enabled I could enumerate them with SerialPort.GetPortNames() which is in the System.IO.Ports NuGet package. My sample code has compile time options for synchronous and asynchronous operation.

//---------------------------------------------------------------------------------
// Copyright (c) September 2021, 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.
//
//---------------------------------------------------------------------------------
namespace devMobile.IoT.NetCore.RAK3172.ShieldSerial
{
	using System;
	using System.Diagnostics;
	using System.IO.Ports;
	using System.Threading;

	public class Program
	{
		private const string SerialPortId = "/dev/ttyS0";

		public static void Main()
		{
			SerialPort serialPort;

			Debug.WriteLine("devMobile.IoT.NetCore.Rak3172.pHatSerial starting");

			Debug.WriteLine(String.Join(",", SerialPort.GetPortNames()));

			try
			{
				serialPort = new SerialPort(SerialPortId);

				// set parameters
				serialPort.BaudRate = 9600;
				serialPort.Parity = Parity.None;
				serialPort.DataBits = 8;
				serialPort.StopBits = StopBits.One;
				serialPort.Handshake = Handshake.None;

				serialPort.ReadTimeout = 1000;

				serialPort.NewLine = "\r\n";

				serialPort.Open();

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

				while (true)
				{
					serialPort.WriteLine("AT+VER=?");

#if SERIAL_SYNC_READ
					// Read the response
					string response = serialPort.ReadLine();
					Debug.WriteLine($"RX:{response.Trim()} bytes:{response.Length}");

					// Read the blank line
					response = serialPort.ReadLine();
					Debug.WriteLine($"RX:{response.Trim()} bytes:{response.Length}");

					// Read the result
					response = serialPort.ReadLine();
					Debug.WriteLine($"RX:{response.Trim()} bytes:{response.Length}");
#endif

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

#if SERIAL_ASYNC_READ
		private static void SerialDevice_DataReceived(object sender, SerialDataReceivedEventArgs e)
		{
			SerialPort serialPort = (SerialPort)sender;

			switch (e.EventType)
			{
				case SerialData.Chars:
					string response = serialPort.ReadExisting();

					Debug.WriteLine($"RX:{response.Trim()} bytes:{response.Length}");
					break;

				case SerialData.Eof:
					Debug.WriteLine("RX :EoF");
					break;
				default:
					Debug.Assert(false, $"e.EventType {e.EventType} unknown");
					break;
			}
		}
#endif
	}
}

When I requested the RAK3172 version information with the AT+VER? command the response was three lines, consisting of the version information, a blank line, then the result of the command. If I sent an invalid command the response was two lines, a blank line then “AT_ERROR”

AT+VER? response synchronous

The asynchronous version of the application displays character(s) as they arrive so a response could be split across multiple SerialDataReceived events

AT+VER? response asynchronous

Unlike the RAK811 module the RAK3172 defaults 9600 baud which means there is no need to change the baudrate before using the device. I use the excellent RaspberryDebugger to download application and debug them on my Raspberry PI 3.

SeeedLoRaE5-NetCore on Github

The source code of my .Net Core C# library for Seeed LoRa-E5 modules used in products like the LoRa-E5 Development Kit, LoRa-E5 mini and Grove-LoRa-E5 is now available on GitHub.

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) September 2021, 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.
//
// Must have one of following options defined in the nfproj file
//    PAYLOAD_BCD or PAYLOAD_BYTES
//    OTAA or ABP
//
// Optional definitions
//    CONFIRMED For confirmed messages
//    RESET for return device to factory settings
//
//---------------------------------------------------------------------------------
namespace devMobile.IoT.NetCore.SeeedE5LoRa.LoRaWanDeviceClient
{
   using System;
   using System.Diagnostics;
   using System.Threading;

   using devMobile.IoT.LoRaWan;

   public class Program
   {
      private const string SerialPortId = "/dev/ttyS0";
      private const string Region = "AS923";
      private static readonly TimeSpan JoinTimeOut = new TimeSpan(0, 0, 20);
      private static readonly TimeSpan SendTimeout = new TimeSpan(0, 0, 15);

      private const byte MessagePort = 15;

#if PAYLOAD_BCD
      private const string PayloadBcd = "010203040506070809";
#endif
#if PAYLOAD_BYTES
      private static readonly byte[] PayloadBytes = { 0x09, 0x08, 0x07, 0x06, 0x05, 0x04, 0x03, 0x02, 0x01 };
#endif

      public static void Main()
      {
         Result result;

         Debug.WriteLine("devMobile.IoT.SeeedE5LoRaWANDeviceClient starting");

         try
         {
            using (SeeedE5LoRaWANDevice device = new SeeedE5LoRaWANDevice())
            {
               result = device.Initialise(SerialPortId, 9600);
               if (result != Result.Success)
               {
                  Debug.WriteLine($"Initialise failed {result}");
                  return;
               }

#if CONFIRMED
               device.OnMessageConfirmation += OnMessageConfirmationHandler;
#endif
               device.OnReceiveMessage += OnReceiveMessageHandler;
#if RESET
               Debug.WriteLine($"{DateTime.UtcNow:hh:mm:ss} Reset");
               result = device.Reset();
               if (result != Result.Success)
               {
                  Debug.WriteLine($"Reset failed {result}");
                  return;
               }
#endif

               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;
               }

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

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

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

               Debug.WriteLine($"{DateTime.UtcNow:hh:mm:ss} Join start Timeout:{JoinTimeOut.TotalSeconds} Seconds");
               result = device.Join(true, JoinTimeOut);
               if (result != Result.Success)
               {
                  Debug.WriteLine($"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.TotalSeconds} Seconds payload BCD:{PayloadBcd}");
#if CONFIRMED
                  result = device.Send(PayloadBcd, true, SendTimeout);
#else
                  result = device.Send(PayloadBcd, false, SendTimeout);
#endif
#endif

#if PAYLOAD_BYTES
                  Debug.WriteLine($"{DateTime.UtcNow:hh:mm:ss} Send Timeout:{SendTimeout.TotalSeconds} Seconds payload Bytes:{BitConverter.ToString(PayloadBytes)}");
#if CONFIRMED
                  result = device.Send(PayloadBytes, true, SendTimeout);
#else
                  result = device.Send(PayloadBytes, false, SendTimeout);
#endif
#endif
                  if (result != Result.Success)
                  {
                     Debug.WriteLine($"Send failed {result}");
                  }

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

                  Thread.Sleep(60000);

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

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

      static void OnReceiveMessageHandler(int port, int rssi, double snr, string payloadBcd)
      {
         byte[] payloadBytes = SeeedE5LoRaWANDevice.BcdToByes(payloadBcd);

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

.NET Core Seeed LoRaE5 LoRaWAN library Part2

Nasty OTAA connect

After getting basic connectivity for my Seeed LoRa-E5 test rig sorted I used RAK7246G LPWAN Developer Gateway on my bookcase to connect to The Things Network(TTN)

Seeed LoRa-E5 Development kit connected to Gove bas shield on a Raspberry PI3

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

The code just sequentially steps through the necessary configuration to join the TTN network with a suitable delay after each command is sent. There also appeared to be quite a variation in response times, especially for joining the network(most probably network related) and the progress of sending a message.

//---------------------------------------------------------------------------------
// Copyright (c) September 2021, 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.
//
//---------------------------------------------------------------------------------
namespace devMobile.IoT.NetCore.SeeedLoRaE5.NetworkJoinOTAA
{
	using System;
	using System.Diagnostics;
	using System.IO.Ports;
	using System.Threading;

	class Program
	{
		private const string SerialPortId = "/dev/ttyS0";

		private const string AppKey = "................................";
		private const string AppEui = "................";

		private const byte MessagePort = 15;

		//private const string Payload = "48656c6c6f204c6f526157414e"; // Hello LoRaWAN
		private const string Payload = "01020304"; // AQIDBA==
		//private const string Payload = "04030201"; // BAMCAQ==

		public static void Main()
		{
			string response;

			Debug.WriteLine("devMobile.IoT.SeeedLoRaE5.NetworkJoinOTAA starting");

			Debug.WriteLine(String.Join(",", SerialPort.GetPortNames()));

			try
			{
				using (SerialPort serialDevice = new SerialPort(SerialPortId))
				{
					// set parameters
					serialDevice.BaudRate = 9600;
					serialDevice.Parity = Parity.None;
					serialDevice.StopBits = StopBits.One;
					serialDevice.Handshake = Handshake.None;
					serialDevice.DataBits = 8;

					serialDevice.ReadTimeout = 10000;

					serialDevice.NewLine = "\r\n";

					serialDevice.Open();

					// clear out the RX buffer
					serialDevice.ReadExisting();
					response = serialDevice.ReadExisting();
					Debug.WriteLine($"Response :{response.Trim()} bytes:{response.Length}");
					Thread.Sleep(500);

					// Set the Region to AS923
					serialDevice.WriteLine("AT+DR=AS923\r\n");
					response = serialDevice.ReadLine();
					Debug.WriteLine($"Response :{response.Trim()} bytes:{response.Length}");

					// Set the Join mode
					serialDevice.WriteLine("AT +MODE=LWOTAA\r\n");
					response = serialDevice.ReadLine();
					Debug.WriteLine($"Response :{response.Trim()} bytes:{response.Length}");

					// Set the appEUI
					serialDevice.WriteLine($"AT+ID=AppEui,\"{AppEui}\"\r\n");
					response = serialDevice.ReadLine();
					Debug.WriteLine($"Response :{response.Trim()} bytes:{response.Length}");

					// Set the appKey
					serialDevice.WriteLine($"AT+KEY=APPKEY,{AppKey}\r\n");
					response = serialDevice.ReadLine();
					Debug.WriteLine($"Response :{response.Trim()} bytes:{response.Length}");

					// Set the port number
					serialDevice.WriteLine($"AT+PORT={MessagePort}\r\n");
					response = serialDevice.ReadLine();
					Debug.WriteLine($"Response :{response.Trim()} bytes:{response.Length}");

					// Join the network
					serialDevice.WriteLine("AT+JOIN\r\n");

					// Join start
					response = serialDevice.ReadLine();
					Debug.WriteLine($"Response :{response.Trim()} bytes:{response.Length}");

					// JOIN normal
					response = serialDevice.ReadLine();
					Debug.WriteLine($"Response :{response.Trim()} bytes:{response.Length}");

					Thread.Sleep(5000);

					// network joined
					response = serialDevice.ReadLine();
					Debug.WriteLine($"Response :{response.Trim()} bytes:{response.Length}");

					// Net ID
					response = serialDevice.ReadLine();
					Debug.WriteLine($"Response :{response.Trim()} bytes:{response.Length}");

					// Join done
					response = serialDevice.ReadLine();
					Debug.WriteLine($"Response :{response.Trim()} bytes:{response.Length}");

					while (true)
					{
						Debug.WriteLine("Sending");

						serialDevice.WriteLine($"AT+MSGHEX=\"{Payload}\"\r\n");

						// Start
						response = serialDevice.ReadLine();
						Debug.WriteLine($"Response :{response.Trim()} bytes:{response.Length}");

						// Fpending
						response = serialDevice.ReadLine();
						Debug.WriteLine($"Response :{response.Trim()} bytes:{response.Length}");

						//Read metrics
						response = serialDevice.ReadLine();
						Debug.WriteLine($"Response :{response.Trim()} bytes:{response.Length}");

						//Done
						response = serialDevice.ReadLine();
						Debug.WriteLine($"Response :{response.Trim()} bytes:{response.Length}");

						Thread.Sleep(30000);
					}
				}
			}
			catch (Exception ex)
			{
				Debug.WriteLine(ex.Message);
			}
		}
	}
}

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

Visual Studio debugger output window showing network join and sensing a message

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

The Things Industries Live Data view showing network join and sensing a message

Most of the LoRaWAN modems I have worked with reply “OK” when a command is successful. The SeeedLoRa-E5 often returns the payload of the request in the response which makes the code a little bit more complex.

AppEui command structure in AT Command documentation

For example the AppEui can be passed in as “00:00:00:00:00:00:00:00” or “0000000000000000” but in the response the format is always “00:00:00:00:00:00:00:00”

.NET Core Seeed LoRaE5 LoRaWAN library Part1

Basic connectivity

Over the weekend I started building a .Net Core C# library for a Seeedstudio LoRa-E5 Development Kit which was connected to a Raspberry PI 3 with a Grove Base Hat for Raspberry Pi

The RaspberryPI OS is a bit more strict than the other devices I use about port access. To allow my .Net Core application to access a serial port I connected to the device with ExtraPutty, then ran the RaspberyPI configuration tool, from the command prompt with “sudo raspi-config”

RaspberyPI OS Software Configuration tool mains screen
RaspberryPI OS IO Serial Port configuration
Raspberry PI OS disabling remote serial login shell
RaspberryPI OS enabling serial port access

Once serial port access was enabled I could enumerate them with SerialPort.GetPortNames() which is in the System.IO.Ports NuGet package. The code has compile time options for synchronous and asynchronous operation.

//---------------------------------------------------------------------------------
// Copyright (c) September 2021, 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.
//
//---------------------------------------------------------------------------------
namespace devMobile.IoT.NetCore.SeeedLoRaE5.ShieldSerial
{
	using System;
	using System.Diagnostics;
	using System.IO.Ports;
	using System.Threading;

	public class Program
	{
		private const string SerialPortId = "/dev/ttyS0";

		public static void Main()
		{
			SerialPort serialPort;

			Debug.WriteLine("devMobile.IoT.NetCore.SeeedLoRaE5.ShieldSerial starting");

			Debug.WriteLine(String.Join(",", SerialPort.GetPortNames()));

			try
			{
				serialPort = new SerialPort(SerialPortId);

				// set parameters
				serialPort.BaudRate = 9600;
				serialPort.Parity = Parity.None;
				serialPort.DataBits = 8;
				serialPort.StopBits = StopBits.One;
				serialPort.Handshake = Handshake.None;

				serialPort.ReadTimeout = 1000;

				serialPort.NewLine = "\r\n";

				serialPort.Open();

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

				while (true)
				{
					serialPort.WriteLine("AT+VER");

#if SERIAL_SYNC_READ
					string response = serialPort.ReadLine();

					Debug.WriteLine($"RX:{response.Trim()} bytes:{response.Length}");
#endif

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

#if SERIAL_ASYNC_READ
		private static void SerialDevice_DataReceived(object sender, SerialDataReceivedEventArgs e)
		{
			SerialPort serialPort = (SerialPort)sender;

			switch (e.EventType)
			{
				case SerialData.Chars:
					string response = serialPort.ReadExisting();

					Debug.WriteLine($"RX:{response.Trim()} bytes:{response.Length}");
					break;

				case SerialData.Eof:
					Debug.WriteLine("RX :EoF");
					break;
				default:
					Debug.Assert(false, $"e.EventType {e.EventType} unknown");
					break;
			}
		}
#endif
	}
}

The synchronous version of the test client requests the Seeeduino LoRa-E5 version information with the AT+VER command.

Synchronously reading characters from the Seeeduino LoRa-E5

The asynchronous version of the application displays character(s) as they arrive so a response can be split across multiple SerialDataReceived events.

Asynchronous versions displaying partial responses

I use the excellent RaspberryDebugger to download the application and debug it on my Raspberry PI 3.

.NET Core 5 Raspberry PI SPI

I have spent a lot of time debugging Serial Peripheral Interface(SPI) device libraries and the .Net Core 5 dotnet/iot library will have its own subtleties(with SPI it’s all about timing). I have written GHI Electronics TinyCLR, Wilderness Labs Meadow, Windows 10 IoT Core, .NET MicroFramework and .NET nanoFramework libraries the SX127X family of devices so building a .Net Core 5 one seemed like a good place to start.

I’m using a Uputronics Raspberry PiZero LoRa(TM) Expansion Board which supports both standard Chip Select(CS) pins (switch selectable which is really useful) and an M2M 1 Channel LoRaWan Gateway Shield for Raspberry PI which has a “non-standard” CS pin.

Uputronics Raspberry PIZero LoRa Expansion board on a Raspberry 3 device

The Uputronics pHat has a pair of Light Emitting Diodes(LEDs) so I adapted some code from a previous post to flash these to confirm the card was working.

static void UputronicsLeds()
{
	const int RedLedPinNumber = 6;
	const int GreenLedPinNumber = 13;

	GpioController controller = new GpioController(PinNumberingScheme.Logical);

	controller.OpenPin(RedLedPinNumber, PinMode.Output);
	controller.OpenPin(GreenLedPinNumber, PinMode.Output);

	while (true)
	{
		if (controller.Read(RedLedPinNumber) == PinValue.Low)
		{
			controller.Write(RedLedPinNumber, PinValue.High);
			controller.Write(GreenLedPinNumber, PinValue.Low);
		}
		else
		{
			controller.Write(RedLedPinNumber, PinValue.Low);
			controller.Write(GreenLedPinNumber, PinValue.High);
		}

		Thread.Sleep(1000);
	}
}

The first Uputronics pHat version using spiDevice.TransferFullDuplex didn’t work. I tried allocating memory for the buffers with new and stackalloc which didn’t seem to make any difference in my trivial example. I tried different Chip Select(CS) pin options, frequencies and modes (the mode used is based on the timings specified in the SX127X datasheet).

static void TransferFullDuplex()
{
	//byte[] writeBuffer = new byte[1]; // Memory allocation didn't seem to make any difference
    //byte[] readBuffer = new byte[1];
	Span<byte> writeBuffer = stackalloc byte[1];
	Span<byte> readBuffer = stackalloc byte[1];

	//var settings = new SpiConnectionSettings(0)
	var settings = new SpiConnectionSettings(0, 0)
	//var settings = new SpiConnectionSettings(0, 1)
	{
		ClockFrequency = 5000000,
		//ClockFrequency = 500000, // Frequency didn't seem to make any difference
		Mode = SpiMode.Mode0,   // From SemTech docs pg 80 CPOL=0, CPHA=0
	};

	SpiDevice spiDevice = SpiDevice.Create(settings);

	Thread.Sleep(500);

	while (true)
	{
		try
		{
			for (byte registerIndex = 0; registerIndex <= 0x42; registerIndex++)
			{
				writeBuffer[0] = registerIndex;
				spiDevice.TransferFullDuplex(writeBuffer, readBuffer);
				//Debug.WriteLine("Register 0x{0:x2} - Value 0X{1:x2} - Bits {2}", writeBuffer[0], readBuffer[0], Convert.ToString(readBuffer[0], 2).PadLeft(8, '0')); // Debug output stopped after roughly 3 times round for loop often debugger would barf as well
				Console.WriteLine("Register 0x{0:x2} - Value 0X{1:x2} - Bits {2}", writeBuffer[0], readBuffer[0], Convert.ToString(readBuffer[0], 2).PadLeft(8, '0'));

				// Would be nice if SpiDevice has a TransferSequential
				/* 
				writeBuffer[0] = registerIndex;
				spiDevice.TransferSequential(writeBuffer, readBuffer);
				Console.WriteLine("Register 0x{0:x2} - Value 0X{1:x2} - Bits {2}", writeBuffer[0], readBuffer[0], Convert.ToString(readBuffer[0], 2).PadLeft(8, '0'));
				*/
			}

			Console.WriteLine("");
			Thread.Sleep(5000);
		}
		catch (Exception ex)
		{
			Console.WriteLine(ex.Message);
		}
	}
}

The second Uputronics pHat version using spiDevice.ReadByte() and spiDevice.WriteBye() didn’t work either.

static void ReadWriteChipSelectStandard()
{
	var settings = new SpiConnectionSettings(0) // Doesn't work
	//	var settings = new SpiConnectionSettings(0, 0) // Doesn't work
	//var settings = new SpiConnectionSettings(0, 1) // Doesn't Work
	{
		ClockFrequency = 5000000,
		ChipSelectLineActiveState = PinValue.Low,
		Mode = SpiMode.Mode0,   // From SemTech docs pg 80 CPOL=0, CPHA=0
	};

	SpiDevice spiDevice = SpiDevice.Create(settings);

	Thread.Sleep(500);

	while (true)
	{
		try
		{
			for (byte registerIndex = 0; registerIndex <= 0x42; registerIndex++)
			{
				spiDevice.WriteByte(registerIndex);
				//Thread.Sleep(5); These made no difference
				//Thread.Sleep(10);
				//Thread.Sleep(20);
				//Thread.Sleep(40);
				byte registerValue = spiDevice.ReadByte();

				Console.WriteLine("Register 0x{0:x2} - Value 0X{1:x2} - Bits {2}", registerIndex, registerValue, Convert.ToString(registerValue, 2).PadLeft(8, '0'));
			}
			Console.WriteLine("");

			Thread.Sleep(5000);
		}
		catch (Exception ex)
		{
			Console.WriteLine(ex.Message);
		}
	}
}

The third Uputronics pHat version using spiDevice.ReadByte() and spiDevice.WriteByte() with DIY Chip Select(CS) worked. In previous SPI device libraries I have found that “managing” the CS line in code can be easier to get working The MicroFramework also has more connectionSettings options for better control of CS line timings which reduces the need for DIY.

static void ReadWriteChipSelectDiy()
{
	const int CSPinNumber = 8; // CS0
	//const int CSPinNumber = 7; // CS1

	// DIY CS0 implented with GPIO pin application controls
	GpioController controller = new GpioController(PinNumberingScheme.Logical);

	controller.OpenPin(CSPinNumber, PinMode.Output);
	//controller.Write(CSPinNumber, PinValue.High);

	//var settings = new SpiConnectionSettings(0) // Doesn't work
	var settings = new SpiConnectionSettings(0, 1) // Works, have to point at unused CS1, this could be a problem is other device on CS1
	//var settings = new SpiConnectionSettings(0, 0) // Works, have to point at unused CS0, this could be a problem is other device on CS0
	{
		ClockFrequency = 5000000,
		Mode = SpiMode.Mode0,   // From SemTech docs pg 80 CPOL=0, CPHA=0
	};

	SpiDevice spiDevice = SpiDevice.Create(settings);

	Thread.Sleep(500);

	while (true)
	{
		try
		{
			for (byte registerIndex = 0; registerIndex <= 0x42; registerIndex++)
			{
				controller.Write(CSPinNumber, PinValue.Low);
				spiDevice.WriteByte(registerIndex);
				//Thread.Sleep(2); // This maybe necessary
				byte registerValue = spiDevice.ReadByte();
				controller.Write(CSPinNumber, PinValue.High);

				Console.WriteLine("Register 0x{0:x2} - Value 0X{1:x2} - Bits {2}", registerIndex, registerValue, Convert.ToString(registerValue, 2).PadLeft(8, '0'));
			}
			Console.WriteLine("");

			Thread.Sleep(5000);
		}
		catch (Exception ex)
		{
			Console.WriteLine(ex.Message);
		}
	}
}

The dotNet/IoT doesn’t support (July2021) the option to “exclusively” open a port so there could be issues with other applications assuming they control CS0/CS1.

Loaded '/usr/lib/dotnet/shared/Microsoft.NETCore.App/5.0.4/Microsoft.Win32.Primitives.dll'. Skipped loading symbols. Module is optimized and the debugger option 'Just My Code' is enabled.
Register 0x00 - Value 0X00 - Bits 00000000
Register 0x01 - Value 0X09 - Bits 00001001
Register 0x02 - Value 0X1a - Bits 00011010
Register 0x03 - Value 0X0b - Bits 00001011
Register 0x04 - Value 0X00 - Bits 00000000
Register 0x05 - Value 0X52 - Bits 01010010
Register 0x06 - Value 0X6c - Bits 01101100
Register 0x07 - Value 0X80 - Bits 10000000
Register 0x08 - Value 0X00 - Bits 00000000
Register 0x09 - Value 0X4f - Bits 01001111
Register 0x0a - Value 0X09 - Bits 00001001
Register 0x0b - Value 0X2b - Bits 00101011
Register 0x0c - Value 0X20 - Bits 00100000
Register 0x0d - Value 0X08 - Bits 00001000
Register 0x0e - Value 0X02 - Bits 00000010
Register 0x0f - Value 0X0a - Bits 00001010
Register 0x10 - Value 0Xff - Bits 11111111
Register 0x11 - Value 0X70 - Bits 01110000
Register 0x12 - Value 0X15 - Bits 00010101
Register 0x13 - Value 0X0b - Bits 00001011
Register 0x14 - Value 0X28 - Bits 00101000
Register 0x15 - Value 0X0c - Bits 00001100
Register 0x16 - Value 0X12 - Bits 00010010
Register 0x17 - Value 0X47 - Bits 01000111
Register 0x18 - Value 0X32 - Bits 00110010
Register 0x19 - Value 0X3e - Bits 00111110
Register 0x1a - Value 0X00 - Bits 00000000
Register 0x1b - Value 0X00 - Bits 00000000
Register 0x1c - Value 0X00 - Bits 00000000
Register 0x1d - Value 0X00 - Bits 00000000
Register 0x1e - Value 0X00 - Bits 00000000
Register 0x1f - Value 0X40 - Bits 01000000
Register 0x20 - Value 0X00 - Bits 00000000
Register 0x21 - Value 0X00 - Bits 00000000
Register 0x22 - Value 0X00 - Bits 00000000
Register 0x23 - Value 0X00 - Bits 00000000
Register 0x24 - Value 0X05 - Bits 00000101
Register 0x25 - Value 0X00 - Bits 00000000
Register 0x26 - Value 0X03 - Bits 00000011
Register 0x27 - Value 0X93 - Bits 10010011
Register 0x28 - Value 0X55 - Bits 01010101
Register 0x29 - Value 0X55 - Bits 01010101
Register 0x2a - Value 0X55 - Bits 01010101
Register 0x2b - Value 0X55 - Bits 01010101
Register 0x2c - Value 0X55 - Bits 01010101
Register 0x2d - Value 0X55 - Bits 01010101
Register 0x2e - Value 0X55 - Bits 01010101
Register 0x2f - Value 0X55 - Bits 01010101
Register 0x30 - Value 0X90 - Bits 10010000
Register 0x31 - Value 0X40 - Bits 01000000
Register 0x32 - Value 0X40 - Bits 01000000
Register 0x33 - Value 0X00 - Bits 00000000
Register 0x34 - Value 0X00 - Bits 00000000
Register 0x35 - Value 0X0f - Bits 00001111
Register 0x36 - Value 0X00 - Bits 00000000
Register 0x37 - Value 0X00 - Bits 00000000
Register 0x38 - Value 0X00 - Bits 00000000
Register 0x39 - Value 0Xf5 - Bits 11110101
Register 0x3a - Value 0X20 - Bits 00100000
Register 0x3b - Value 0X82 - Bits 10000010
Register 0x3c - Value 0Xf6 - Bits 11110110
Register 0x3d - Value 0X02 - Bits 00000010
Register 0x3e - Value 0X80 - Bits 10000000
Register 0x3f - Value 0X40 - Bits 01000000
Register 0x40 - Value 0X00 - Bits 00000000
Register 0x41 - Value 0X00 - Bits 00000000
Register 0x42 - Value 0X12 - Bits 00010010

The fourth Uputronics pHat version using spiDevice.TransferFullDuplex with read and write buffers two bytes long and the leading bye of the response ignored worked.

...
while (true)
{
	try
	{
		for (byte registerIndex = 0; registerIndex <= 0x42; registerIndex++)
		{
			// Doesn't work
			writeBuffer[0] = registerIndex;
			spiDevice.TransferFullDuplex(writeBuffer, readBuffer);
			Console.WriteLine("Register 0x{0:x2} - Value 0X{1:x2} - Bits {2}", registerIndex, readBuffer[0], Convert.ToString(readBuffer[0], 2).PadLeft(8, '0'));

			// Does work
			writeBuffer[0] = registerIndex;
			spiDevice.TransferFullDuplex(writeBuffer, readBuffer);
			Console.WriteLine("Register 0x{0:x2} - Value 0X{1:x2} - Bits {2}", registerIndex, readBuffer[1], Convert.ToString(readBuffer[1], 2).PadLeft(8, '0'));

			// Does work
			writeBuffer[1] = registerIndex;
			spiDevice.TransferFullDuplex(writeBuffer, readBuffer);
			Console.WriteLine("Register 0x{0:x2} - Value 0X{1:x2} - Bits {2}", registerIndex, readBuffer[1], Convert.ToString(readBuffer[1], 2).PadLeft(8, '0'));

			Console.WriteLine("");
		}

		Console.WriteLine("");
		Thread.Sleep(5000);
	}
	catch (Exception ex)
	{
		Console.WriteLine(ex.Message);
	}
}

Register 0x00 - Value 0X00 - Bits 00000000
Register 0x00 - Value 0X00 - Bits 00000000
Register 0x00 - Value 0X00 - Bits 00000000

...

Register 0x42 - Value 0X00 - Bits 00000000
Register 0x42 - Value 0X12 - Bits 00010010
Register 0x42 - Value 0X12 - Bits 00010010

M2M Single channel shield on Raspberry Pi 3 Device

The first M2M pHat version using SpiDevice.Read and SpiDevice.Write with a “custom” CS pin worked.

...
// Chip select with pin which isn't CS0 or CS1 needs M2M shield
static void ReadWriteDiyChipSelectNonStandard()
{
	const int CSPinNumber = 25;

	// DIY CS0 implented with GPIO pin application controls
	GpioController controller = new GpioController(PinNumberingScheme.Logical);

	controller.OpenPin(CSPinNumber, PinMode.Output);
	//controller.Write(CSPinNumber, PinValue.High);

	// Work, this could be a problem is other device on CS0/CS1
	var settings = new SpiConnectionSettings(0)
	//var settings = new SpiConnectionSettings(0, 0) 
	//var settings = new SpiConnectionSettings(0, 1) 
	{
		ClockFrequency = 5000000,
		Mode = SpiMode.Mode0,   // From SemTech docs pg 80 CPOL=0, CPHA=0
	};

	SpiDevice spiDevice = SpiDevice.Create(settings);

	Thread.Sleep(500);

	while (true)
	{
		try
		{
			for (byte registerIndex = 0; registerIndex <= 0x42; registerIndex++)
			{
				controller.Write(CSPinNumber, PinValue.Low);
				spiDevice.WriteByte(registerIndex);
				//Thread.Sleep(2); // This maybe necessary
				byte registerValue = spiDevice.ReadByte();
				controller.Write(CSPinNumber, PinValue.High);

				Console.WriteLine("Register 0x{0:x2} - Value 0X{1:x2} - Bits {2}", registerIndex, registerValue, Convert.ToString(registerValue, 2).PadLeft(8, '0'));
			}
			Console.WriteLine("");

			Thread.Sleep(5000);
		}
		catch (Exception ex)
		{
			Console.WriteLine(ex.Message);
		}
	}
}

The second M2M pHat version using SpiDevice.TransferFullDuplex with a “custom” CS pin also worked.

while (true)
{
	try
	{
		for (byte registerIndex = 0; registerIndex <= 0x42; registerIndex++)
		{
			writeBuffer[0] = registerIndex;
			//writeBuffer[1] = registerIndex;

			controller.Write(CSPinNumber, PinValue.Low);
			spiDevice.TransferFullDuplex(writeBuffer, readBuffer);
			controller.Write(CSPinNumber, PinValue.High);

			Console.WriteLine("Register 0x{0:x2} - Value 0X{1:x2} - Bits {2}", registerIndex, readBuffer[1], Convert.ToString(readBuffer[1], 2).PadLeft(8, '0'));
		}
		Console.WriteLine("");

		Thread.Sleep(5000);
	}
	catch (Exception ex)
	{
		Console.WriteLine(ex.Message);
	}
}

The next step was to read an array of bytes, using spiDevice.TransferFullDuplex. The SX127X transmit/receive frequency is specified in registers 0x06 RegFrMSB, 0x07 RegFrMid, and 0x08 RegFrLsb. The default frequency is 868MHz which is 0xE4, 0xC0, 0x00

static void TransferFullDuplexBufferBytesRead()
{ 
	const byte length = 3;
	byte[] writeBuffer = new byte[length + 1];
	byte[] readBuffer = new byte[length + 1];

	// Read the frequency which is 3 bytes RegFrMsb 0x6c, RegFrMid 0x80, RegFrLsb 0x00
	writeBuffer[0] = 0x06; //

	// Works, have to point at unused CS0/CS1, others could be a problem is another another SPI device is on on CS0/CS1
	//var settings = new SpiConnectionSettings(0)
	var settings = new SpiConnectionSettings(0, 0) 
	//var settings = new SpiConnectionSettings(0, 1) 
	{
		ClockFrequency = 5000000,
		Mode = SpiMode.Mode0,   // From SemTech docs pg 80 CPOL=0, CPHA=0
	};

	SpiDevice spiDevice = SpiDevice.Create(settings);

	spiDevice.TransferFullDuplex(writeBuffer, readBuffer);

	Console.WriteLine($"Register 0x06-0x{readBuffer[1]:x2} 0x07-0x{readBuffer[2]:x2} 0x08-0x{readBuffer[3]:x2}");
}
-------------------------------------------------------------------
You may only use the Microsoft .NET Core Debugger (vsdbg) with
Visual Studio Code, Visual Studio or Visual Studio for Mac software
to help you develop and test your applications.
-------------------------------------------------------------------
Loaded '/usr/lib/dotnet/shared/Microsoft.NETCore.App/5.0.4/System.Private.CoreLib.dll'. Skipped loading symbols. Module is optimized and the debugger option 'Just My Code' is enabled.
...
Loaded '/usr/lib/dotnet/shared/Microsoft.NETCore.App/5.0.4/Microsoft.Win32.Primitives.dll'. Skipped loading symbols. Module is optimized and the debugger option 'Just My Code' is enabled.
Register 0x06-0xe4 0x07-0xc0 0x08-0x00

The final step was write an array of bytes, using spiDevice.TransferFullDuplex to change the transmit/receive frequency to 915MHz. To write a value the first bit of the address byte must be set to 1 hence the 0x86 RegFrMsb address.

static void TransferFullDuplexBufferBytesWrite()
{
	const byte length = 3;
	byte[] writeBuffer = new byte[length + 1];
	byte[] readBuffer = new byte[length + 1];

	// Write the frequency which is 3 bytes RegFrMsb 0x6c, RegFrMid 0x80, RegFrLsb or with 0x00 the write mask
	writeBuffer[0] = 0x86 ;

	// Works, have to point at unused CS0/CS1, others could be a problem is another another SPI device is on on CS0/CS1
	//var settings = new SpiConnectionSettings(0)
	var settings = new SpiConnectionSettings(0, 0)
	//var settings = new SpiConnectionSettings(0, 1) 
	{
		ClockFrequency = 5000000,
		Mode = SpiMode.Mode0,   // From SemTech docs pg 80 CPOL=0, CPHA=0
	};

	SpiDevice spiDevice = SpiDevice.Create(settings);

	// Set the frequency to 915MHz
	writeBuffer[1] = 0xE4;
	writeBuffer[2] = 0xC0;
	writeBuffer[3] = 0x00;

	spiDevice.TransferFullDuplex(writeBuffer, readBuffer);
}

-------------------------------------------------------------------
You may only use the Microsoft .NET Core Debugger (vsdbg) with
Visual Studio Code, Visual Studio or Visual Studio for Mac software
to help you develop and test your applications.
-------------------------------------------------------------------
Loaded '/usr/lib/dotnet/shared/Microsoft.NETCore.App/5.0.4/System.Private.CoreLib.dll'. Skipped loading symbols. Module is optimized and the debugger option 'Just My Code' is enabled.
...
Loaded '/usr/lib/dotnet/shared/Microsoft.NETCore.App/5.0.4/Microsoft.Win32.Primitives.dll'. Skipped loading symbols. Module is optimized and the debugger option 'Just My Code' is enabled.
Register 0x06-0x6c 0x07-0x80 0x08-0x00
Register 0x06-0xe4 0x07-0xc0 0x08-0x00
The program 'dotnet' has exited with code 0 (0x0).

Summary

This exceptionally long post was to highlight that with SPI it’s all about timing, first read the datasheet, then build code to validate your understanding.

SX127X SPI interface timing diagram

Some platforms have native TransferSequential implementations but the dotNet/IoT library only has TransferFullDuplex. SPI hardware is always full duplex, if “sequential” is available the implementation will write the provided bytes and then follow them with zeros to read the requested bytes.

.NET Core 5 Raspberry PI GPIO Interrupts

To port my Windows 10 IoT Core nRF24L01, SX123X. and SX127X LoRa libraries to .Net Core 5 I wanted to see if there were any differences in the way interrupts were handled by the dotnet/iot libraries. The initial versions of the code will being running on a Raspberry PI but I will also look at other supported Single Board Computers(SBCs).

My test-rig was a RaspberryPI 3B with a Grove Base Hat for Raspberry PI (left over from a proof of concept project), a couple of Grove Universal 4 pin 5CM cables, a Grove LED pack, and a Grove Button.

Raspberry PI test rig with Grove Base pHat, button & LED

There were some syntax differences but nothing to major

using System;
using System.Device.Gpio;
using System.Diagnostics;
using System.Threading;

namespace devMobile.NetCore.GPIOInterrupts
{
	class Program
	{
		private const int ButtonPinNumber = 5;
		private const int LedPinNumber = 16;
		private static GpioController gpiocontroller;

		static void Main(string[] args)
		{
			try
			{
				gpiocontroller = new GpioController(PinNumberingScheme.Logical);

				gpiocontroller.OpenPin(ButtonPinNumber, PinMode.InputPullDown);
				gpiocontroller.OpenPin(LedPinNumber, PinMode.Output);

				gpiocontroller.RegisterCallbackForPinValueChangedEvent(ButtonPinNumber, PinEventTypes.Rising, PinChangeEventHandler);

				Console.WriteLine($"Main thread:{Thread.CurrentThread.ManagedThreadId}");

				while (true)
				{
					Console.WriteLine($"Doing stuff");
					Thread.Sleep(1000);
				}
			}
			catch (Exception ex)
			{
				Console.WriteLine(ex.Message);
			}
		}

		private static void PinChangeEventHandler(object sender, PinValueChangedEventArgs pinValueChangedEventArgs)
		{
			Debug.Write($"Interrupt Thread:{Thread.CurrentThread.ManagedThreadId}");

			if (pinValueChangedEventArgs.ChangeType == PinEventTypes.Rising)
			{
				if (gpiocontroller.Read(LedPinNumber) == PinValue.Low)
				{
					gpiocontroller.Write(LedPinNumber, PinValue.High);
				}
				else
				{
					gpiocontroller.Write(LedPinNumber, PinValue.Low);
				}
			}
		}
	}
}

I included code to display the Thread.CurrentThread.ManagedThreadId to see if the callback was running on a different thread.

-------------------------------------------------------------------
You may only use the Microsoft .NET Core Debugger (vsdbg) with
Visual Studio Code, Visual Studio or Visual Studio for Mac software
to help you develop and test your applications.
-------------------------------------------------------------------
...
Loaded '/usr/lib/dotnet/shared/Microsoft.NETCore.App/5.0.4/Microsoft.Win32.Primitives.dll'. Skipped loading symbols. Module is optimized and the debugger option 'Just My Code' is enabled.
Main thread:1
Doing stuff
Doing stuff
Doing stuff
Doing stuff
Doing stuff
Interrupt Thread:6Doing stuff
Doing stuff
Doing stuff
Interrupt Thread:6Doing stuff
Doing stuff
Interrupt Thread:6Doing stuff
Doing stuff
Doing stuff
Doing stuff
Doing stuff
Doing stuff
The program 'dotnet' has exited with code 0 (0x0).

The ManagedThreadId for the main loop(1) was different to the callback(6) which needs some further investigation.

.NET Core 5 Raspberry PI GPIO

Next to my desk I have a stack of Raspberry PI’s and with the release of .Net Core 5 for Windows, Macintosh and Linux I decided to have another look at porting some of my nRF24L01, LoRa, and LoRaWAN libraries to .Net Core.

There are blog posts (like Deploying and Debugging Raspberry Pi .NET Applications using VS Code) about installing .Net core on a Raspberry PI, using Visual Studio Code to write an application, then deploying and debugging it over SSH which were interesting but there were a lot of steps so the likelihood me screwing up was high.

I have been using Visual Studio for C# and VB.Net code since .Net was first released (I wrote my first C# applications with Visual Studio 6) so when I stumbled across RaspberryDebugger it was time to unbox a Raspberry PI 3B and see what happened.

All coding demos start with Hello world

using System;
using System.Diagnostics;
using System.Threading;

namespace devMobile.NetCore.ConsoleApp
{
	class Program
	{
		static void Main(string[] args)
		{
			while (true)
			{
				Console.WriteLine($"{DateTime.UtcNow:HH:mm:ss} Hello World!");

				Thread.Sleep(1000);
			}
		}
	}
}

The RaspberryDebugger is really simple to install, and “frictionless” to use. The developers have put a lot of effort into making it easy to deploy and debug a .Net Core application running on a Raspberry PI with Visual Studio. All I had to do was search for, then download and install their Visual Studio Extension(VSIX).

Visual Studio Manage Extensions search

Then configure the connection information for the devices I wanted to use.

Visual Studio Options menu for RaspberryDebugger

On my main development system I was using multiple Raspberry PI devices so it was great to be able to pre-configure several devices.

RaspberryDebugger device(s) configuration)

I had connected to each device with PuTTY to check that connectivity was sorted.

RaspberryDebugger devices configuration device configuration

After typing in my “Hello world” application I had to select the device I wanted to use

Project menu RaspberryDebugger option
RaspberryDebugger device selection

Then I pressed F5 and it worked! It’s very unusual for things to work first time so I was stunned. The application was “automagically” downloaded and run in the debugger on the device.

-------------------------------------------------------------------
You may only use the Microsoft .NET Core Debugger (vsdbg) with
Visual Studio Code, Visual Studio or Visual Studio for Mac software
to help you develop and test your applications.
-------------------------------------------------------------------
Loaded '/usr/lib/dotnet/shared/Microsoft.NETCore.App/5.0.4/System.Private.CoreLib.dll'. Skipped loading symbols. Module is optimized and the debugger option 'Just My Code' is enabled.
Loaded '/home/pi/vsdbg/ConsoleApp/ConsoleApp.dll'. Symbols loaded.
Loaded '/usr/lib/dotnet/shared/Microsoft.NETCore.App/5.0.4/System.Runtime.dll'. Skipped loading symbols. Module is optimized and the debugger option 'Just My Code' is enabled.
Loaded '/usr/lib/dotnet/shared/Microsoft.NETCore.App/5.0.4/System.Console.dll'. Skipped loading symbols. Module is optimized and the debugger option 'Just My Code' is enabled.
Loaded '/usr/lib/dotnet/shared/Microsoft.NETCore.App/5.0.4/System.Threading.Thread.dll'. Skipped loading symbols. Module is optimized and the debugger option 'Just My Code' is enabled.
Loaded '/usr/lib/dotnet/shared/Microsoft.NETCore.App/5.0.4/System.Threading.dll'. Skipped loading symbols. Module is optimized and the debugger option 'Just My Code' is enabled.
Loaded '/usr/lib/dotnet/shared/Microsoft.NETCore.App/5.0.4/System.Text.Encoding.Extensions.dll'. Skipped loading symbols. Module is optimized and the debugger option 'Just My Code' is enabled.
Loaded '/usr/lib/dotnet/shared/Microsoft.NETCore.App/5.0.4/Microsoft.Win32.Primitives.dll'. Skipped loading symbols. Module is optimized and the debugger option 'Just My Code' is enabled.
05:50:37 Hello World!
05:50:39 Hello World!
05:50:40 Hello World!
05:50:41 Hello World!
05:50:42 Hello World!
05:50:43 Hello World!
...

Once the basics were sorted I wanted to check out the General Purpose Input & Output(GPIO) support implemented in the dotnet/iot libraries. My test-rig was a RaspberryPI 3B with a Grove Base Hat for Raspberry PI (left over from a Windows 10 IoT Core proof of concept project), a couple of Grove Universal 4 pin 5CM cables, a Grove LED pack, and a Grove Button.

Raspberry PI test rig with Grove Base pHat, button & LED
using System;
using System.Device.Gpio;
using System.Diagnostics;
using System.Threading;

namespace devMobile.NetCore.ConsoleGPIO1
{
	class Program
	{
		const int ButtonPinNumber = 5;
		const int LedPinNumber = 16;

		static void Main(string[] args)
		{
			try
			{
				GpioController controller = new GpioController(PinNumberingScheme.Logical);

				controller.OpenPin(ButtonPinNumber, PinMode.InputPullUp);
				controller.OpenPin(LedPinNumber, PinMode.Output);

				while (true)
				{
					if (controller.Read(ButtonPinNumber) == PinValue.High)
					{
						if (controller.Read(LedPinNumber) == PinValue.Low)
						{
							controller.Write(LedPinNumber, PinValue.High);
						}
						else
						{
							controller.Write(LedPinNumber, PinValue.Low);
						}
					}
					Thread.Sleep(100);
				}
			}
			catch (Exception ex)
			{
				Console.WriteLine(ex.Message);
			}
		}
	}
}

After starting the application, when I pressed the button the Grove LED flashed with a 100mSec duty cycle.

The RaspberryDebugger extension is a joy to use and I’m going to figure out how I can donate some money to the developers.