nanoFramework LoRa library Part6

Transmit and Receive with Interrupts

For the final revision my nanoFramework SX127X Library test harness I checked interrupts were working for the interleaved transmission and reception of messages.

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

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

         if ((irqFlags & 0b01000000) == 0b01000000)  // RxDone 
         {
            Console.WriteLine("Receive-Message");
            byte currentFifoAddress = this.RegisterReadByte(0x10); // RegFifiRxCurrent
            this.RegisterWriteByte(0x0d, currentFifoAddress); // RegFifoAddrPtr

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

            // Allocate buffer for message
            byte[] messageBytes = this.RegisterRead(0X0, numberOfBytes);

            // Remove unprintable characters from messages
            for (int index = 0; index < messageBytes.Length; index++)
            {
               if ((messageBytes[index] < 0x20) || (messageBytes[index] > 0x7E))
               {
                  messageBytes[index] = 0x20;
               }
            }

            string messageText = UTF8Encoding.UTF8.GetString(messageBytes,0, messageBytes.Length);
            Console.WriteLine($"Received {messageBytes.Length} byte message {messageText}");
         }

         if ((irqFlags & 0b00001000) == 0b00001000)  // TxDone
         {
            this.RegisterWriteByte(0x01, 0b10000101); // RegOpMode set LoRa & RxContinuous
            Console.WriteLine("Transmit-Done");
         }

         this.RegisterWriteByte(0x40, 0b00000000); // RegDioMapping1 0b00000000 DI0 RxReady & TxReady
         this.RegisterWriteByte(0x12, 0xff);// RegIrqFlags
      }

…
class Program
{
      static void Main()
      {
         int SendCount = 0;
#if ST_STM32F429I_DISCOVERY
         int chipSelectPinNumber = PinNumber('C', 2);
         int resetPinNumber = PinNumber('C', 3);
         int interruptPinNumber = PinNumber('A', 4);
#endif
#if ESP32_WROOM_32_LORA_1_CHANNEL
         int chipSelectPinNumber = Gpio.IO16;
         int interruptPinNumber = Gpio.IO26;
#endif

         try
         {
#if ESP32_WROOM_32_LORA_1_CHANNEL
            Configuration.SetPinFunction(Gpio.IO12, DeviceFunction.SPI1_MISO);
            Configuration.SetPinFunction(Gpio.IO13, DeviceFunction.SPI1_MOSI);
            Configuration.SetPinFunction(Gpio.IO14, DeviceFunction.SPI1_CLOCK);
            Rfm9XDevice rfm9XDevice = new Rfm9XDevice(SpiBusId, chipSelectPinNumber, interruptPinNumber);
#endif
#if ST_STM32F429I_DISCOVERY
            Rfm9XDevice rfm9XDevice = new Rfm9XDevice(SpiBusId, chipSelectPinNumber, resetPinNumber, interruptPinNumber);
#endif
            Thread.Sleep(500);

            // Put device into LoRa + Standby 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
               Console.WriteLine($"Sending {messageBytes.Length} bytes message {messageText}");
               rfm9XDevice.RegisterWriteByte(0x01, 0b10000011); // RegOpMode 

               Thread.Sleep(10000);
            }
         }
         catch (Exception ex)
         {
            Console.WriteLine(ex.Message);
         }
      }

The diagnostic output shows inbound and outbound messages

'nanoFramework.Tools.VS2019.Extension.dll' (Managed): Loaded 'C:\Users\BrynLewis\source\repos\RFM9X.NetNF\packages\nanoFramework.Hardware.Esp32.1.2.1-preview.10\lib\nanoFramework.Hardware.Esp32.dll', Symbols loaded.
The thread '<No Name>' (0x2) has exited with code 0 (0x0).
Sending 13 bytes message Hello LoRa 1!
RegIrqFlags 0X08
Transmit-Done
RegIrqFlags 0X50
Receive-Message
Received 17 byte message HeLoRa World! 136
Sending 13 bytes message Hello LoRa 2!
RegIrqFlags 0X08
Transmit-Done
RegIrqFlags 0X50
Receive-Message
Received 17 byte message HeLoRa World! 138
Sending 13 bytes message Hello LoRa 3!
RegIrqFlags 0X08
Transmit-Done
RegIrqFlags 0X50
Receive-Message
Received 17 byte message HeLoRa World! 140
20:32:58.079 -> Sending HeLoRa World! 134
20:33:04.553 -> Message: Hello LoRa 1!
20:33:04.553 -> Length: 13
20:33:04.587 -> FirstChar: 72
20:33:04.587 -> RSSI: -52
20:33:04.587 -> Snr: 9.50
20:33:04.622 -> 
20:33:08.137 -> Sending HeLoRa World! 136
20:33:14.568 -> Message: Hello LoRa 2!
20:33:14.568 -> Length: 13
20:33:14.602 -> FirstChar: 72
20:33:14.602 -> RSSI: -53
20:33:14.602 -> Snr: 9.75
20:33:14.635 -> 
20:33:19.135 -> Sending HeLoRa World! 138
20:33:24.560 -> Message: Hello LoRa 3!
20:33:24.560 -> Length: 13
20:33:24.594 -> FirstChar: 72
20:33:24.594 -> RSSI: -52
20:33:24.594 -> Snr: 9.25
20:33:24.628 -> 

There did appear to be some oddness (leading to corrupted first message) with the RegOpMode setting(0b10000000 vs. 0b10000001) for my STM32F429 Discovery and Sparkfun LoRa Gateway 1 Channel ESP32.

I think it maybe due to the Discovery having the rest line connected but unlike the Sparkfun LoRa Gateway.

nanoFramework LoRa library Part1

After writing my Windows 10 IoT Core RFM9X library and porting it to .NetMF, Wilderness Labs Meadow and GHI Electronics TinyCLR-OS I figured yet another platform port shouldn’t take too long.

To get started I used a Dragino LoRa shield for Arduino and jumper wires to connect it to my STM32F4 Discovery Kit running the nanoFramework.

Dragino Arduino LoRa Shield Schematic

My initial pin mapping was

  • SCK->PF7->D10
  • MISO->PF8->D12
  • MOSI->PF9->D11
  • CS->PC2->D10

The shield uses D10 for chip select, D2 for RFM9X DI0 interrupt and D9 for Reset. The shield ships with the SPI lines configured for ICSP so the three jumpers diagonally across the shield from the antenna connector need to be swapped to the side closest to the edge of the shield.

STM32F429 Discovery kit with Dragino Shield

First step was to confirm I could (using the nanoFramework GPIO and SPI Nuget packages) read a couple of the Semtech SX1276 registers.

//---------------------------------------------------------------------------------
// Copyright (c) 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.
//
//---------------------------------------------------------------------------------
namespace devMobile.IoT.Rfm9x.ShieldSPI
{
   using System;
   using System.Threading;

   using Windows.Devices.Gpio;
   using Windows.Devices.Spi;

   public class Program
   {
      public static void Main()
      {
         try
         {
            GpioController gpioController = GpioController.GetDefault();

            GpioPin chipSelectGpioPin = gpioController.OpenPin(PinNumber('C', 2));
            chipSelectGpioPin.SetDriveMode(GpioPinDriveMode.Output);

            var settings = new SpiConnectionSettings(chipSelectGpioPin.PinNumber)
            {
               ClockFrequency = 500000,
               Mode = SpiMode.Mode0,// From SemTech docs pg 80 CPOL=0, CPHA=0
               //Mode = SpiMode.Mode1,
               //Mode = SpiMode.Mode2,
               //Mode = SpiMode.Mode3,
               SharingMode = SpiSharingMode.Shared,
               //SharingMode = SpiSharingMode.Exclusive,
            };
            

            SpiDevice Device = SpiDevice.FromId("SPI5", settings);

            Thread.Sleep(500);

            while (true)
            {
               byte[] writeBuffer = new byte[] { 0x42 };
               byte[] readBuffer = new byte[1];
            
               //Device.Write(writeBuffer);
               //Device.Read(readBuffer);
               Device.TransferSequential(writeBuffer, readBuffer);

               byte registerValue = readBuffer[0];
               Console.WriteLine(String.Format("Register 0x{0:x2} - Value 0X{1:x2}", 0x42, registerValue));

               Thread.Sleep(10000);
            }
         }
         catch (Exception ex)
         {
            Console.WriteLine(ex.Message);
         }
      }

      static int PinNumber(char port, byte pin)
      {
         if (port < 'A' || port > 'J')
            throw new ArgumentException();

         return ((port - 'A') * 16) + pin;
      }
   }
}

After trying many permutations of settings I could successfully read the RegVersion and default frequency values

Attaching to nanoDevice...
Waiting for nanoDevice to initialize...
Updating nanoDevice debugger engine.
The nanoDevice runtime is loading the application assemblies and starting execution.
'nanoFramework.Tools.VS2019.Extension.dll' (Managed): Loaded 'C:\Users\BrynLewis\source\repos\RFM9X.NetNF\ShieldSPI\bin\Debug\ShieldSPI.exe', Symbols loaded.
'nanoFramework.Tools.VS2019.Extension.dll' (Managed): Loaded 'C:\Users\BrynLewis\source\repos\RFM9X.NetNF\packages\nanoFramework.Windows.Devices.Spi.1.3.0-preview.12\lib\Windows.Devices.Spi.dll', Symbols loaded.
'nanoFramework.Tools.VS2019.Extension.dll' (Managed): Loaded 'C:\Users\BrynLewis\source\repos\RFM9X.NetNF\packages\nanoFramework.Runtime.Events.1.4.2-preview.1\lib\nanoFramework.Runtime.Events.dll', Symbols loaded.
'nanoFramework.Tools.VS2019.Extension.dll' (Managed): Loaded 'C:\Users\BrynLewis\source\repos\RFM9X.NetNF\packages\nanoFramework.Windows.Devices.Gpio.1.4.1-preview.13\lib\Windows.Devices.Gpio.dll', Symbols loaded.
The thread '<No Name>' (0x2) has exited with code 0 (0x0).
Register 0x42 - Value 0X12
Register 0x42 - Value 0X12

Mapping the Discovery board pins to corresponding SPI and GPIO pins was a bit painful