Category Archives: .Net

.NET nanoFramework RAK2305

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The RAKwireless RAK2305 WisBlock WiFi Interface Module (WisBlock Wireless-IO Slot) is based on an Expressif ESP32 processor which is supported by the .NET nanoFramework. The first step was to solder some headers onto the RAK2305 so I could connect an FTDI module to get Universal Serial Bus(USB) connectivity.

RAK2305 + FTDI Test

After a small delay the RAK2305 appeared in Windows Device Manager on COM4

My first attempt to “flash” the RAK2305 with the nano Firmware Flasher(nanoff) failed

nanoff flashing failure

The RAK2305 Low Level Developer documentation described how to upload software developed with the Arduino tools by putting the ESP32 into “bootloader mode”. This is done by connecting (with the white jumper) the GPIO0 and GND pins on J14, and pressing the reset button.


nanoff flashing success

The first step with any embedded development project is to flash a Light Emitting Diode(LED)….

The RAK2305 has has one onboard LED(TEST_LED) attached to IO18 which I added to the .NET nanoFramework Blinky sample.

//
// Copyright (c) .NET Foundation and Contributors
// See LICENSE file in the project root for full license information.
//
//
using System;
using System.Device.Gpio;
using System.Threading;
using nanoFramework.Hardware.Esp32;

namespace Blinky
{
   public class Program
   {
      private static GpioController s_GpioController;

      public static void Main()
      {
         s_GpioController = new GpioController();

         // pick a board, uncomment one line for GpioPin; default is STM32F769I_DISCO

         // DISCOVERY4: PD15 is LED6 
         //GpioPin led = s_GpioController.OpenPin(PinNumber('D', 15), PinMode.Output);

         // ESP32 DevKit: 4 is a valid GPIO pin in, some boards like Xiuxin ESP32 may require GPIO Pin 2 instead.
         //GpioPin led = s_GpioController.OpenPin(4, PinMode.Output);

         // FEATHER S2: 
         //GpioPin led = s_GpioController.OpenPin(13, PinMode.Output);

         // F429I_DISCO: PG14 is LEDLD4 
         //GpioPin led = s_GpioController.OpenPin(PinNumber('G', 14), PinMode.Output);

         // NETDUINO 3 Wifi: A10 is LED onboard blue
         //GpioPin led = s_GpioController.OpenPin(PinNumber('A', 10), PinMode.Output);

         // QUAIL: PE15 is LED1  
         //GpioPin led = s_GpioController.OpenPin(PinNumber('E', 15), PinMode.Output);

         // STM32F091RC: PA5 is LED_GREEN
         //GpioPin led = s_GpioController.OpenPin(PinNumber('A', 5), PinMode.Output);

         // STM32F746_NUCLEO: PB75 is LED2
         //GpioPin led = s_GpioController.OpenPin(PinNumber('B', 7), PinMode.Output);

         //STM32F769I_DISCO: PJ5 is LD2
         //GpioPin led = s_GpioController.OpenPin(PinNumber('J', 5), PinMode.Output);

         // ST_B_L475E_IOT01A: PB14 is LD2
         //GpioPin led = s_GpioController.OpenPin(PinNumber('B', 14), PinMode.Output);

         // STM32L072Z_LRWAN1: PA5 is LD2
         //GpioPin led = s_GpioController.OpenPin(PinNumber('A', 5), PinMode.Output);

         // TI CC13x2 Launchpad: DIO_07 it's the green LED
         //GpioPin led = s_GpioController.OpenPin(7, PinMode.Output);

         // TI CC13x2 Launchpad: DIO_06 it's the red LED  
         //GpioPin led = s_GpioController.OpenPin(6, PinMode.Output);

         // ULX3S FPGA board: for the red D22 LED from the ESP32-WROOM32, GPIO5
         //GpioPin led = s_GpioController.OpenPin(5, PinMode.Output);

         // Silabs SLSTK3701A: LED1 PH14 is LLED1
         //GpioPin led = s_GpioController.OpenPin(PinNumber('H', 14), PinMode.Output);

         // RAK11200 on RAK5005
         //GpioPin led = s_GpioController.OpenPin(Gpio.IO12, PinMode.Output); // LED1 Green
         //GpioPin led = s_GpioController.OpenPin(Gpio.IO02, PinMode.Output); // LED2 Blue

         // RAK11200 on RAK19001 needs battery connected or power switch in rechargeable position.
         //GpioPin led = s_GpioController.OpenPin(Gpio.IO12, PinMode.Output); // LED1 Green
         //GpioPin led = s_GpioController.OpenPin(Gpio.IO02, PinMode.Output); // LED2 Blue

         // RAK2305 
         //GpioPin led = s_GpioController.OpenPin(Gpio.IO18, PinMode.Output); // LED Green (Test LED) on device

         // RAK2305 On 5005 throws exceptions
         //GpioPin led = s_GpioController.OpenPin(Gpio.IO34, PinMode.Output); // LED1 Green
         //GpioPin led = s_GpioController.OpenPin(Gpio.IO35, PinMode.Output); // LED2 Blue

         // RAK2305 On 17001 throws exceptions
         //GpioPin led = s_GpioController.OpenPin(Gpio.IO34, PinMode.Output); // LED1 Green
         //GpioPin led = s_GpioController.OpenPin(Gpio.IO35, PinMode.Output); // LED2 Blue

         led.Write(PinValue.Low);

         while (true)
         {
            led.Toggle();
            Thread.Sleep(125);
            led.Toggle();
            Thread.Sleep(125);
            led.Toggle();
            Thread.Sleep(125);
            led.Toggle();
            Thread.Sleep(525);
         }
      }

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

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

I added the RAK2305 configuration to my version of the nanoFramework Blinky sample and could reliably flash the onboard LED.

.NET nanoFramework RAK3172 Library Usage

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After a two week “soak test” using a Sparkfun Thing Plus ESP32 WROOM and RAK3172 Breakout Board completed with no failures, this final post covers the usage of the RAK3172LoRaWAN-NetNF library in a “real-world” application.

Sparkfun Thing Plus ESP32 WROOM and RAK3172 Breakout Board test rig
Discovery kit with STM32F769NI MCU and RAK3172 Breakout Board test rig

Before a factory reset the DevEUI, JoinEUI (was AppEUI), and AppKey were values I had configured earlier

12:02:04 0 TX:AT+DEVEUI=? bytes:11--------------------------------
AT+DEVEUI=A..............1
OK

12:03:05 0 TX:AT+APPEUI=? bytes:11--------------------------------
AT+APPEUI=A..............8
OK

12:04:03 0 TX:AT+APPKEY=? bytes:11--------------------------------
AT+APPKEY=C..............................F
OK

After a factory reset the DevEUI, JoinEUI (was AppEUI), and AppKey were default values

12:00:21 0 TX:AT+DEVEUI=? bytes:11--------------------------------
AT+DEVEUI=0000000000000000
OK

12:01:09 0 TX:AT+APPEUI=? bytes:11--------------------------------
AT+APPEUI=0000000000000000
OK

12:01:48 0 TX:AT+APPKEY=? bytes:11--------------------------------
AT+APPKEY=00000000000000000000000000000000
OK

I then ran the RAK3172LoRaWANDeviceClient with the following preprocessor directives defined to reconfigure the RAK3172 module.

//---------------------------------------------------------------------------------
//#define ST_STM32F769I_DISCOVERY      // nanoff --target ST_STM32F769I_DISCOVERY --update 
#define ESP32_WROOM   // nanoff --target ESP32_REV0 --serialport COM17 --update
#define DEVICE_DEVEUI_SET
//#define FACTORY_RESET
///#define PAYLOAD_BCD
#define PAYLOAD_BYTES
#define OTAA
//#define ABP
//#define CONFIRMED
#define UNCONFIRMED
#define REGION_SET
#define ADR_SET
//#define SLEEP
namespace devMobile.IoT.LoRaWAN
{
...
Visual Studio Debug output for RAK3172LoRaWANDeviceClient full configuration

I could then run the RAK3172LoRaWANDeviceClient with only PAYLOAD_BCD or PAYLOAD_BYTES defined

//---------------------------------------------------------------------------------
//#define ST_STM32F769I_DISCOVERY      // nanoff --target ST_STM32F769I_DISCOVERY --update 
#define ESP32_WROOM   // nanoff --target ESP32_REV0 --serialport COM17 --update
//#define DEVICE_DEVEUI_SET
//#define FACTORY_RESET
///#define PAYLOAD_BCD
#define PAYLOAD_BYTES
//#define OTAA
//#define ABP
//#define CONFIRMED
//#define UNCONFIRMED
//#define REGION_SET
//#define ADR_SET
//#define SLEEP
namespace devMobile.IoT.LoRaWAN
{
...
Visual Studio Debug output for RAK3172LoRaWANDeviceClient minimal configuration
public static void Main()
{
	Result result;

	Debug.WriteLine("devMobile.IoT.RAK3172LoRaWANDeviceClient starting");

	try
	{
		// set GPIO functions for COM2 (this is UART1 on ESP32)
#if ESP32_WROOM
		Configuration.SetPinFunction(Gpio.IO17, DeviceFunction.COM2_TX);
		Configuration.SetPinFunction(Gpio.IO16, DeviceFunction.COM2_RX);
#endif

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

		using (Rak3172LoRaWanDevice device = new Rak3172LoRaWanDevice())
		{
			result = device.Initialise(SerialPortId, 115200, Parity.None, 8, StopBits.One);
			if (result != Result.Success)
			{
				Debug.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 FACTORY_RESET
			Debug.WriteLine($"{DateTime.UtcNow:hh:mm:ss} FactoryReset");
			result = device.FactoryReset();
			if (result != Result.Success)
			{
				Debug.WriteLine($"FactoryReset failed {result}");
				return;
			}
#endif

#if DEVICE_DEVEUI_SET
			Debug.WriteLine($"{DateTime.UtcNow:hh:mm:ss} Device EUI");
			result = device.DeviceEui(Config.devEui);
			if (result != Result.Success)
			{
				Debug.WriteLine($"DeviceEUI set failed {result}");
				return;
			}
#endif

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

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

#if OTAA
			Debug.WriteLine($"{DateTime.UtcNow:hh:mm:ss} OTAA");
			result = device.OtaaInitialise(Config.JoinEui, Config.AppKey);
			if (result != Result.Success)
			{
				Debug.WriteLine($"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($"{DateTime.UtcNow:hh:mm:ss} Join start Timeout:{JoinTimeOut:hh:mm:ss}");
			result = device.Join(JoinTimeOut);
			if (result != Result.Success)
			{
				Debug.WriteLine($"Join failed {result}");
				return;
			}
			Debug.WriteLine($"{DateTime.UtcNow:hh:mm:ss} Join started");

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

One of the major differences between the RAK4200 and RAK3127 libraries is the way a LoRaWAN network join is handled. The RAK4200 library Join method blocks until it succeeds of fails, the RAK3172 library Join method returns immediately then an EventHandler is called with the result.

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

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

The new RAK Wireless LoRaWAN modules use the RUI3 AT Commands so the RAK3172 library will most probably be retired and uses as the basis for a generic RUI3 library.

.NET nanoFramework RAK11200 – UART GPS

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The RAKwireless RAK11200 WisBlock WiFi Module module is based on an Expressif ESP32 processor which is supported by the .NET nanoFramework and I wanted try out it out with a RAK1910 GNSS GPS Location Module.

RAK11200, RAK5005-O and RAK1910 with GPS Antenna

The RAK WinBlock Pin Mapper tool output for RAK1910, RAK5005-O WisBlock Base Board and RAK11200

The test application is based on the TinyGPSPlusNF library by MBoude which parses the NMEA 0183 sentences produced by the RAK1910. 

public class Program
{
    private static TinyGPSPlus _gps;

    public static void Main()
    {
        Debug.WriteLine($"devMobile.IoT.RAK.Wisblock.Max7Q starting TinyGPS {TinyGPSPlus.LibraryVersion}");

        Configuration.SetPinFunction(Gpio.IO21, DeviceFunction.COM2_TX);
        Configuration.SetPinFunction(Gpio.IO19, DeviceFunction.COM2_RX);

        _gps = new TinyGPSPlus();

        // UART1 with default Max7Q baudrate
        SerialPort serialPort = new SerialPort("COM2", 9600);

        serialPort.DataReceived += SerialDevice_DataReceived;
        serialPort.Open();
        serialPort.WatchChar = '\n';

         // // Enable the with GPS 3V3_S/RESET_GPS - IO2 - GPIO27
        GpioController gpioController = new GpioController();

        GpioPin Gps3V3 = gpioController.OpenPin(Gpio.IO27, PinMode.Output);
        Gps3V3.Write(PinValue.High);

        Debug.WriteLine("Waiting...");

        Thread.Sleep(Timeout.Infinite);
    }

    private static void SerialDevice_DataReceived(object sender, SerialDataReceivedEventArgs e)
    {
        // we only care if got EoL character
        if (e.EventType != SerialData.WatchChar)
        {
            return;
        }

        SerialPort serialDevice = (SerialPort)sender;

        string sentence = serialDevice.ReadExisting();

        if (_gps.Encode(sentence))
        {
            if (_gps.Date.IsValid)
            {
                Debug.Write($"{_gps.Date.Year}-{_gps.Date.Month:D2}-{_gps.Date.Day:D2} ");
            }

            if (_gps.Time.IsValid)
            {
                Debug.Write($"{_gps.Time.Hour:D2}:{_gps.Time.Minute:D2}:{_gps.Time.Second:D2}.{_gps.Time.Centisecond:D2} ");
            }

            if (_gps.Location.IsValid)
            {
                Debug.Write($"Lat:{_gps.Location.Latitude.Degrees:F5}° Lon:{_gps.Location.Longitude.Degrees:F5}° ");
            }

            if (_gps.Altitude.IsValid)
            {
                Debug.Write($"Alt:{_gps.Altitude.Meters:F1}M");
            }

            if (_gps.Date.IsValid || _gps.Time.IsValid || _gps.Location.IsValid || _gps.Altitude.IsValid)
            {
                Debug.WriteLine("");
            }
        }
    }
}
Visual Studio 2K22 Output Window

.NET nanoFramework RAK11200 – I2C SHT3C & SHT31

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The RAKwireless RAK11200 WisBlock WiFi Module module is based on an Expressif ESP32 processor which is supported by the .NET nanoFramework and I wanted to explore the different ways Inter-Integrated Circuit(I2C) devices could be connected.

The RAK11200 WisBlock WiFi Module has two I2C ports and on the RAK5005 WisBlock Base Board the Wisblock Sensor, and RAK1920 WisBlock Sensor Adapter Module Grove Socket are connected to I2C1.

RAK11200 Schematic

The I2C1 the SDA(serial data) and SCL(serial clock line) have to be mapped to physical pins on the RAK11200 WisBlock WiFi Module using the nanoFramework ESP32 support NuGet. package

                Configuration.SetPinFunction(Gpio.IO04, DeviceFunction.I2C1_DATA);
                Configuration.SetPinFunction(Gpio.IO05, DeviceFunction.I2C1_CLOCK)

The first sample project uses a RAK1901 SHTC3 WisBlock Sensor because it plugs into the RAK5005 WisBlock Base Board.

RAK5005 Baseboard, RAK1901 Sensor and RAK11200 Core WisBlock modules
public static void Main()
{
    Debug.WriteLine("devMobile.IoT.RAK.Wisblock.SHTC3 starting");

    try
    {
        Configuration.SetPinFunction(Gpio.IO04, DeviceFunction.I2C1_DATA);
        Configuration.SetPinFunction(Gpio.IO05, DeviceFunction.I2C1_CLOCK);

        I2cConnectionSettings settings = new(1, Shtc3.DefaultI2cAddress);

        using (I2cDevice device = I2cDevice.Create(settings))
        using (Shtc3 shtc3 = new(device))
        {
            while (true)
            {
                if (shtc3.TryGetTemperatureAndHumidity(out var temperature, out var relativeHumidity))
                {
                    Debug.WriteLine($"Temperature {temperature.DegreesCelsius:F1}°C  Humidity {relativeHumidity.Value:F0}%");
                }

                Thread.Sleep(10000);
            }
        }
    }
    catch (Exception ex)
    {
        Debug.WriteLine($"SHTC3 initialisation or read failed {ex.Message}");

        Thread.Sleep(Timeout.Infinite);
    }
}
Visual Studio Output window displaying SHT3C temperature & humidity values

The second sample uses a Seeedstudio Grove – Temperature & Humidity Sensor (SHT31) pluged into a RAK1920 Sensor Adapter for Click, QWIIC and Grove Modules.

RAK5005 Baseboard, RAK1920 Sensor, RAK11200 Core WisBlock modules and Seeedstudio Grove SHT31
public static void Main()
{
    Debug.WriteLine("devMobile.IoT.RAK.Wisblock.SHT31 starting");

    try
    {
        Configuration.SetPinFunction(Gpio.IO04, DeviceFunction.I2C1_DATA);
        Configuration.SetPinFunction(Gpio.IO05, DeviceFunction.I2C1_CLOCK);

        I2cConnectionSettings settings = new(1, (byte)I2cAddress.AddrLow);

        using (I2cDevice device = I2cDevice.Create(settings))
        using (Sht3x sht31 = new(device))
        {

            while (true)
            {
                var temperature = sht31.Temperature;
                var relativeHumidity = sht31.Humidity;

                Debug.WriteLine($"Temperature {temperature.DegreesCelsius:F1}°C  Humidity {relativeHumidity.Value:F0}%");

                Thread.Sleep(10000);
            }
        }
    }
    catch (Exception ex)
    {
        Debug.WriteLine($"SHT31 initialisation or read failed {ex.Message}");

        Thread.Sleep(Timeout.Infinite);
     }
}
Visual Studio Output window displaying SHT31 temperature & humidity values

The SHTC3 and SHT31 sensors were used because they both have nanoFramework.IoTDevice library support.

.NET nanoFramework RAK11200

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The RAKwireless RAK11200 WisBlock WiFi Module module is based on an Expressif ESP32 processor which is supported by the .NET nanoFramework. The first step was to mount the RAK11200 on a RAK5005 WisBlock Base Board to get Universal Serial Bus(USB) connectivity.

RAK11200 Mounted on RAK5005 base board

My first attempt “flash” the RAK11200 with the nano Firmware Flasher(nanoff) failed badly

nanoff flashing failure

The RAK11200 documentation described how to upload software developed with the Arduino tools by putting the ESP32 into “bootloader mode” by connecting the BOOT0 and GND pins, then pressing the reset button.

RAK11200 BOOT0 & GND pins connected to

After some “trial and error” the download process worked pretty reliably…

nanoff flashing success

The first step with any embedded development project is to flash a Light Emitting Diode(LED)….

RAK11200 Schematic

The RAK11200 has two LEDs, a blue attached to IO02 and a green one attached to IO12. 

//
// Copyright (c) .NET Foundation and Contributors
// See LICENSE file in the project root for full license information.
//
//
using System;
using System.Device.Gpio;
using System.Threading;
using nanoFramework.Hardware.Esp32;

namespace Blinky
{
   public class Program
   {
      private static GpioController s_GpioController;
      public static void Main()
      {
         s_GpioController = new GpioController();

         // pick a board, uncomment one line for GpioPin; default is STM32F769I_DISCO

         // DISCOVERY4: PD15 is LED6 
         //GpioPin led = s_GpioController.OpenPin(PinNumber('D', 15), PinMode.Output);

         // ESP32 DevKit: 4 is a valid GPIO pin in, some boards like Xiuxin ESP32 may require GPIO Pin 2 instead.
         //GpioPin led = s_GpioController.OpenPin(4, PinMode.Output);

         // FEATHER S2: 
         //GpioPin led = s_GpioController.OpenPin(13, PinMode.Output);

         // F429I_DISCO: PG14 is LEDLD4 
         //GpioPin led = s_GpioController.OpenPin(PinNumber('G', 14), PinMode.Output);

         // NETDUINO 3 Wifi: A10 is LED onboard blue
         //GpioPin led = s_GpioController.OpenPin(PinNumber('A', 10), PinMode.Output);

         // QUAIL: PE15 is LED1  
         //GpioPin led = s_GpioController.OpenPin(PinNumber('E', 15), PinMode.Output);

         // STM32F091RC: PA5 is LED_GREEN
         //GpioPin led = s_GpioController.OpenPin(PinNumber('A', 5), PinMode.Output);

         // STM32F746_NUCLEO: PB75 is LED2
         //GpioPin led = s_GpioController.OpenPin(PinNumber('B', 7), PinMode.Output);

         //STM32F769I_DISCO: PJ5 is LD2
         //GpioPin led = s_GpioController.OpenPin(PinNumber('J', 5), PinMode.Output);

         // ST_B_L475E_IOT01A: PB14 is LD2
         //GpioPin led = s_GpioController.OpenPin(PinNumber('B', 14), PinMode.Output);

         // STM32L072Z_LRWAN1: PA5 is LD2
         //GpioPin led = s_GpioController.OpenPin(PinNumber('A', 5), PinMode.Output);

         // TI CC13x2 Launchpad: DIO_07 it's the green LED
         //GpioPin led = s_GpioController.OpenPin(7, PinMode.Output);

         // TI CC13x2 Launchpad: DIO_06 it's the red LED  
         //GpioPin led = s_GpioController.OpenPin(6, PinMode.Output);

         // ULX3S FPGA board: for the red D22 LED from the ESP32-WROOM32, GPIO5
         //GpioPin led = s_GpioController.OpenPin(5, PinMode.Output);

         // Silabs SLSTK3701A: LED1 PH14 is LLED1
         //GpioPin led = s_GpioController.OpenPin(PinNumber('H', 14), PinMode.Output);

         // RAK11200 on RAK5005
         //GpioPin led = s_GpioController.OpenPin(Gpio.IO12, PinMode.Output); // LED1 Green
         //GpioPin led = s_GpioController.OpenPin(Gpio.IO02, PinMode.Output); // LED2 Blue

         // RAK11200 on RAK19001 needs battery connected or power switch in rechargeable position.
         //GpioPin led = s_GpioController.OpenPin(Gpio.IO12, PinMode.Output); // LED1 Green
         //GpioPin led = s_GpioController.OpenPin(Gpio.IO02, PinMode.Output); // LED2 Blue

         // RAK2305 
         //GpioPin led = s_GpioController.OpenPin(Gpio.IO18, PinMode.Output); // LED Green (Test LED) on device

         // RAK2305 On 5005 throws exceptions
         //GpioPin led = s_GpioController.OpenPin(Gpio.IO34, PinMode.Output); // LED1 Green
         //GpioPin led = s_GpioController.OpenPin(Gpio.IO35, PinMode.Output); // LED2 Blue

         // RAK2305 On 17001 throws exceptions
         //GpioPin led = s_GpioController.OpenPin(Gpio.IO34, PinMode.Output); // LED1 Green
         //GpioPin led = s_GpioController.OpenPin(Gpio.IO35, PinMode.Output); // LED2 Blue

         led.Write(PinValue.Low);

         while (true)
         {
            led.Toggle();
            Thread.Sleep(125);
            led.Toggle();
            Thread.Sleep(125);
            led.Toggle();
            Thread.Sleep(125);
            led.Toggle();
            Thread.Sleep(525);
         }
      }

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

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

I added the RAK11200 configuration to my version of the nanoFramework Blinky sample and could reliably flash either of the LEDs.

.NET nanoFramework RAK3172 Sleep

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The RAKwireless RAK3172 module has “AT+SLEEP -Sleep mode command. To see how it worked I modified the BreakOutSerial application to send an AT-SLEEP command.

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

	Debug.WriteLine("devMobile.IoT.LoRaWAN.nanoFramework.RAK3172 BreakoutSerial starting");

	try
	{
		// set GPIO functions for COM2 (this is UART1 on ESP32)
#if ESP32_WROOM
		Configuration.SetPinFunction(Gpio.IO17, DeviceFunction.COM2_TX);
		Configuration.SetPinFunction(Gpio.IO16, DeviceFunction.COM2_RX);
#endif

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

		using (_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.NewLine = "\r\n";
			_SerialPort.ReadTimeout = 1000;

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

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

			_SerialPort.Open();

			_SerialPort.WatchChar = '\n';

			_SerialPort.ReadExisting(); // Running at 115K2 this was necessary

#if SERIAL_THREADED_READ
			readThread.Start();
#endif

			for (int i = 0; i < 5; i++)
			{
				string atCommand;
				atCommand = "AT+VER=?";
				//atCommand = "AT+SN=?"; // Empty response?
				//atCommand = "AT+HWMODEL=?";
				//atCommand = "AT+HWID=?";
				//atCommand = "AT+DEVEUI=?";
				//atCommand = "AT+APPEUI=?";
				//atCommand = "AT+APPKEY=?";
				//atCommand = "ATR";
				//atCommand = "AT+SLEEP=4000";
				Debug.WriteLine("");
				Debug.WriteLine($"{DateTime.UtcNow:hh:mm:ss} {i} TX:{atCommand} bytes:{atCommand.Length}--------------------------------");
				_SerialPort.WriteLine(atCommand);

				Thread.Sleep(5000);
			}
		}
#if SERIAL_THREADED_READ
		_Continue = false;
#endif
		Debug.WriteLine("Done");
	}
	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:
			break;

		case SerialData.WatchChar:
			string response = serialPort.ReadExisting();
			//Debug.Write($"{DateTime.UtcNow:hh:mm:ss} RX:{response} bytes:{response.Length}");
			Debug.Write(response);
			break;
		default:
			Debug.Assert(false, $"e.EventType {e.EventType} unknown");
			break;
	}
}
#endif

I then ran the device in the debugger to see how the AT+SLEEP was handled.

BreakoutSerial application executing AT+SLEEP command

There was limited AT+SLEEP -Sleep mode documentation but it looks like the RAK3172 module sleeps, “wakes up” and then replies with “OK”.

Sparkfun Thing Plus ESP32 WROOM + RAK3172 Idle power consumption

Initially the Sleep method didn’t appear to work, the power consumption didn’t change…. 

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

#if PAYLOAD_HEX
	Debug.WriteLine($"{DateTime.UtcNow:hh:mm:ss} port:{MessagePort} payload HEX:{PayloadHex}");
	Result result = device.Send(MessagePort, PayloadHex, SendTimeout);
#endif
#if PAYLOAD_BYTES
	Debug.WriteLine($"{DateTime.UtcNow:hh:mm:ss} port:{MessagePort} payload bytes:{Rak3172LoRaWanDevice.BytesToHex(PayloadBytes)}");
	Result result = device.Send(MessagePort, PayloadBytes, SendTimeout);
#endif
	if (result != Result.Success)
	{
		Debug.WriteLine($"Send failed {result}");
	}

#if SLEEP
	Thread.Sleep(7500); //10000 Works 5000 to short

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

After some debugging and reading this helpful RAK Wireless forum post I added a short delay before sleeping the RAK3172 module and power consumption reduced.

Sparkfun Thing Plus ESP32 WROOM + RAK3172 Sleep mode power consumption

Initially the Sleep method timed out every time it was called. After some more debugging I figured out that I needed a slightly longer delay for the AutoResetEvent.Waitone as it was timing out just before the “OK” was processed. 

public Result Sleep(TimeSpan period)
{
	return Sleep(period, SleepExtensionDefault);
}

public Result Sleep(TimeSpan period, TimeSpan extension)
{
#if DIAGNOSTICS
	Debug.WriteLine($" {DateTime.UtcNow:hh:mm:ss} AT+SLEEP {period.TotalMilliseconds:f0} mSec");
#endif
	Result result = SendCommand("OK", $"AT+SLEEP={period.TotalMilliseconds:f0}", period.Add(extension));
	if (result != Result.Success)
	{
#if DIAGNOSTICS
		Debug.WriteLine($" {DateTime.UtcNow:hh:mm:ss} AT+SLEEP failed {result}");
#endif
		return result;
	}

	return Result.Success;
}

I then disconnected RAK3172 module to see how much power the Sparkfun Thing Plus ESP32 WROOM was using.

Sparkfun Thing Plus ESP32 WROOM power consumption

The nanoFramework ESP32 support library has a LightSleep and DeepSleep functionality which significantly reduced the power consumption

Sparkfun Thing Plus ESP32 WROOM LightSleep power consumption
Sparkfun Thing Plus ESP32 WROOM DeepSleep power consumption

The Keweisi KWS-MX19 USB Tester DC 4V-30V 0-5A Current Voltage Detector is not a precision laboratory instrument but did show the power consumption of my setup could be reduced by sleeping the RAK3172 module and the Sparkfun Thing Plus ESP32 WROOM.

.NET nanoFramework RAK3172 Factory Reset

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The RAKwireless RAK3172 module has “ATR – Restore to Default Parameters” command. To see what settings were “restored” I modified the BreakOutSerial application to send an ATR command to reset the device, then display the DevEUI, JoinEUI, and AppKey.

public static void Main()
{
	Debug.WriteLine("devMobile.IoT.LoRaWAN.nanoFramework.RAK3172 BreakoutSerial starting");

	try
	{
		// set GPIO functions for COM2 (this is UART1 on ESP32)
#if ESP32_WROOM
		Configuration.SetPinFunction(Gpio.IO17, DeviceFunction.COM2_TX);
		Configuration.SetPinFunction(Gpio.IO16, DeviceFunction.COM2_RX);
#endif

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

		using (_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.NewLine = "\r\n";
			_SerialPort.ReadTimeout = 1000;

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

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

			_SerialPort.Open();

			_SerialPort.WatchChar = '\n';

			_SerialPort.ReadExisting(); // Running at 115K2 this was necessary

...

			for (int i = 0; i < 5; i++)
			{
				string atCommand;
				atCommand = "AT+VER=?";
				//atCommand = "AT+SN=?"; // Empty response?
				//atCommand = "AT+HWMODEL=?";
				//atCommand = "AT+HWID=?";
				//atCommand = "AT+DEVEUI=?";
				//atCommand = "AT+APPEUI=?";
				//atCommand = "AT+APPKEY=?";
				//atCommand = "ATR";
				//atCommand = "AT+SLEEP=4000";
				Debug.WriteLine("");
				Debug.WriteLine($"{i} TX:{atCommand} bytes:{atCommand.Length}--------------------------------");
				_SerialPort.WriteLine(atCommand);

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

After resetting the device I modified the code to display some of the configuration.

DevEUI after ATR command
JoinEUI after ATR command
AppKey after ATR command

To reconfigure the device I ran the RAK3172LoRaWANDeviceClient application with DEVICE_DEVEUI_SET, OTAA, UNCONFIRMED, REGION_SET and ADR_SET defined. The testrig could then successfully connect to The Things Network and when the device was power cycled the configuration was retained.

public Result FactoryReset()
{
#if DIAGNOSTICS
	Debug.WriteLine($" {DateTime.UtcNow:hh:mm:ss} ATR");
#endif
	Result result = SendCommand("OK", "ATR", CommandTimeoutDefault);
	if (result != Result.Success)
	{
#if DIAGNOSTICS
		Debug.WriteLine($" {DateTime.UtcNow:hh:mm:ss} ATR failed {result}");
#endif
		return result;
	}

	return Result.Success;
}

I have added a “FactoryReset” method to the RAK3172LoRaWANDevice library.

.NET nanoFramework RAK3172 LoRaWAN library ABP Join

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After getting my RAKwireless RAK3172 module to reliably connect to The Things Network(TTN) using Over The Air Activation(OTAA) the next step was to built an Activation By Personalisation(ABP) sample application.

SparkFun Thing Plus – ESP32 WROOM, RAK3172 Breakout board

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

namespace devMobile.IoT.LoRaWAN.nanoFramework.RAK3172
{
	using System;
	using System.Diagnostics;
	using System.IO.Ports;
	using System.Threading;
#if ESP32_WROOM
	using global::nanoFramework.Hardware.Esp32; //need NuGet nanoFramework.Hardware.Esp32
#endif

	public class Program
	{
#if ESP32_WROOM
		private const string SerialPortId = "COM2";
#endif
#if ST_STM32F769I_DISCOVERY
		private const string SerialPortId = "COM6";
#endif
		private const string DevEui = "...";
		private const string DevAddress = "...";
		private const string NwksKey = "...";
		private const string AppsKey = "..."; 
		private const byte MessagePort = 1;
		private const string Payload = "A0EEE456D02AFF4AB8BAFD58101D2A2A"; // Hello LoRaWAN

		public static void Main()
		{
			Debug.WriteLine("devMobile.IoT.LoRaWAN.nanoFramework.RAK3172.NetworkJoinABP starting");

			try
			{
				// set GPIO functions for COM2 (this is UART1 on ESP32)
#if ESP32_WROOM
				Configuration.SetPinFunction(Gpio.IO17, DeviceFunction.COM2_TX);
				Configuration.SetPinFunction(Gpio.IO16, DeviceFunction.COM2_RX);
#endif

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

				using (SerialPort 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.NewLine = "\r\n";
					serialPort.ReadTimeout = 1000;

					serialPort.DataReceived += SerialDevice_DataReceived;

					serialPort.Open();

					serialPort.WatchChar = '\n';

					serialPort.ReadExisting(); // Running at 115K2 this was necessary

					// Set the Device EUI
					Console.WriteLine("Set Device EUI");
					serialPort.WriteLine($"AT+DEVEUI={DevEui}");

					// Set the Working mode to LoRaWAN
					Console.WriteLine("Set Work mode");
					serialPort.WriteLine("AT+NWM=1");

					// Set the Region to AS923
					Console.WriteLine("Set Region");
					serialPort.WriteLine("AT+BAND=8");

					// Set the JoinMode
					Console.WriteLine("Set Join mode");
					serialPort.WriteLine("AT+NJM=0");

					// Set the DevAddress
					Console.WriteLine("Set Device Address");
					serialPort.WriteLine($"AT+DEVADDR={DevAddress}");

					// Set the Network Session Key
					Console.WriteLine("Set NwksKey");
					serialPort.WriteLine($"AT+NWKSKEY={NwksKey}");

					// Set the Application Session Key
					Console.WriteLine("Set AppsKey");
					serialPort.WriteLine($"AT+APPSKEY={AppsKey}");

					// Set the Confirm flag
					Console.WriteLine("Set Confirm off");
					serialPort.WriteLine("AT+CFM=0");

					// Join the network
					Console.WriteLine("Start Join");
					serialPort.WriteLine("AT+JOIN=1:0:10:2");

					// Wait for the +EVT:JOINED

					while (true)
					{
						Console.WriteLine("Sending");
						serialPort.WriteLine($"AT+SEND={MessagePort}:{Payload}");

						Thread.Sleep(300000);
					}
				}
			}
			catch (Exception ex)
			{
				Debug.WriteLine(ex.Message);
			}
		}

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

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

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

The NetworkJoinABP application assumes that all of the AT commands succeed.

TTN Console live data tab connection process
Visual Studio Output windows displaying connection process and a D2C message
TTN Console live data tab connection process with a couple of D2C messages
Visual Studio Output windows displaying connection process and a couple of C2D messages

The Activation By Personalisation(ABP) sample was a bit more fragile than I expected. The The Things Network(TTN) Live Data Tab updates were often delayed or required a page refresh to be displayed (July 2022).

.NET nanoFramework RAK3172 LoRaWAN library OTAA Join

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When I first tried Over The Air Activation(OTAA) to connect to The Things Network(TTN) with my RAKwireless RAK3172 module it didn’t work. I had flashed my Sparkfun Thing plus ESP32 WROOM with the ESP32 PSRAM binaries (Thanks AlbertK on the nanoFramework Discord).

nanoff --target ESP32_REV0 --serialport COM17 --update
RAK3172 Sparkfun ESP32 WROOM Testrig

I modified the NetworkJoinOTAA sample (based on the asynchronous version of BreakOutSerial) to send the sequence of AT commands to join The Things Network(TTN) and display the responses.

#define ST_STM32F769I_DISCOVERY      // nanoff --target ST_STM32F769I_DISCOVERY --update 
//#define ESP32_WROOM   //nanoff --target ESP32_REV0 --serialport COM17 --update

namespace devMobile.IoT.LoRaWAN.nanoFramework.RAK3172
{
	using System;
	using System.Diagnostics;
	using System.IO.Ports;
	using System.Threading;
#if ESP32_WROOM
	using global::nanoFramework.Hardware.Esp32; //need NuGet nanoFramework.Hardware.Esp32
#endif

	public class Program
	{
#if ESP32_WROOM
		private const string SerialPortId = "COM2";
#endif
#if ST_STM32F769I_DISCOVERY
		private const string SerialPortId = "COM6";
#endif
		private const string DevEui = "...";
		private const string AppEui = "...";
		private const string AppKey = "...";
		private const byte MessagePort = 1;
		private const string Payload = "A0EEE456D02AFF4AB8BAFD58101D2A2A"; // Hello LoRaWAN

		public static void Main()
		{
			Debug.WriteLine("devMobile.IoT.LoRaWAN.nanoFramework.RAK3172 NetworkJoinOTAA starting");

			try
			{
				// set GPIO functions for COM2 (this is UART1 on ESP32)
#if ESP32_WROOM
				Configuration.SetPinFunction(Gpio.IO17, DeviceFunction.COM2_TX);
				Configuration.SetPinFunction(Gpio.IO16, DeviceFunction.COM2_RX);
#endif

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

				using (SerialPort 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.NewLine = "\r\n";
					serialPort.ReadTimeout = 1000;

					serialPort.DataReceived += SerialDevice_DataReceived;

					serialPort.Open();

					serialPort.WatchChar = '\n';

					serialPort.ReadExisting(); // Running at 115K2 this was necessary

					// Set the devEUI
					Console.WriteLine("Set Dev Eui");
					serialPort.WriteLine($"AT+DEVEUI={DevEui}");

					// Set the Working mode to LoRaWAN
					Console.WriteLine("Set Work mode");
					serialPort.WriteLine("AT+NWM=1");

					// Set the Region to AS923
					Console.WriteLine("Set Region");
					serialPort.WriteLine("AT+BAND=8");

					// Set the JoinMode
					Console.WriteLine("Set Join mode");
					serialPort.WriteLine("AT+NJM=1");

					// Set the appEUI
					Console.WriteLine("Set App Eui");
					serialPort.WriteLine($"AT+APPEUI={AppEui}");

					// Set the appKey
					Console.WriteLine("Set App Key");
					serialPort.WriteLine($"AT+APPKEY={AppKey}");

					// Set the Confirm flag
					Console.WriteLine("Set Confirm off");
					serialPort.WriteLine("AT+CFM=0");

					// Join the network
					Console.WriteLine("Start Join");
					serialPort.WriteLine("AT+JOIN=1:0:10:2");

					// Wait for the +EVT:JOINED

					while (true)
					{
						Console.WriteLine("Sending");
						serialPort.WriteLine($"AT+SEND={MessagePort}:{Payload}");

						Thread.Sleep(300000);
					}
				}
			}
			catch (Exception ex)
			{
				Debug.WriteLine(ex.Message);
			}
		}

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

			switch (e.EventType)
			{
				case SerialData.Chars:
					break;
 
				case SerialData.WatchChar:
					string response = serialPort.ReadExisting();
					Debug.Write(response);
					break;
				default:
					Debug.Assert(false, $"e.EventType {e.EventType} unknown");
					break;
			}
		}
	}
}
Visual Studio Debug Output displaying Configuration-Join-Send
Things Network(TTN) Live Data tab display successful join then D2C message

The NetworkJoinOTAA application assumes that all of the AT commands succeed. I usually step though the application in the debugger so I can monitor progress.

.NET nanoFramework RAK3172 LoRaWAN library basic connectivity

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I have been working on a .NET nanoFramework library for the RAKwireless RAK3172 module for the last couple of weeks. The devices had been in a box under my desk for a couple of months so first step was to flash them with the latest firmware using my FTDI test harness.

RAK 3172 STM32F769I Discovery test rig
RAK Device firmware update tool

I use two hardware configurations for testing

STM32F769I Discovery, RAK3172 Breakout Board, and Grove Base Shield for Arduino
SparkFun Thing Plus – ESP32 WROOM (Micro-B) and RAK3172 Breakout Board

My sample code has compile time options for synchronous and asynchronous operation. I also include the different nanoff command lines to make updating the test devices easier.

//---------------------------------------------------------------------------------
// 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.
//
// https://docs.rakwireless.com/Product-Categories/WisDuo/RAK4200-Breakout-Board/AT-Command-Manual/
//---------------------------------------------------------------------------------
#define SERIAL_ASYNC_READ
//#define SERIAL_THREADED_READ
#define ST_STM32F769I_DISCOVERY      // nanoff --target ST_STM32F769I_DISCOVERY --update 
//#define ESP32_WROOM   // nanoff --target ESP32_REV0 --serialport COM17 --update
...

namespace devMobile.IoT.LoRaWAN.nanoFramework.RAK3172
{
	using System;
	using System.Diagnostics;
	using System.IO.Ports;
	using System.Threading;
#if ESP32_WROOM
	using global::nanoFramework.Hardware.Esp32; //need NuGet nanoFramework.Hardware.Esp32
#endif

	public class Program
	{
		private static SerialPort _SerialPort;
#if SERIAL_THREADED_READ
		private static Boolean _Continue = true;
#endif
#if ESP32_WROOM
		private const string SerialPortId = "COM2";
#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.RAK3172 BreakoutSerial starting");

			try
			{
				// set GPIO functions for COM2 (this is UART1 on ESP32)
#if ESP32_WROOM
				Configuration.SetPinFunction(Gpio.IO16, DeviceFunction.COM2_TX);
				Configuration.SetPinFunction(Gpio.IO17, DeviceFunction.COM2_RX);
#endif

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

				using (_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.NewLine = "\r\n";
					_SerialPort.ReadTimeout = 1000;

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

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

					_SerialPort.Open();

					_SerialPort.WatchChar = '\n';

#if SERIAL_THREADED_READ
					readThread.Start();
#endif

					for (int i = 0; i < 5; i++)
					{
						string atCommand;
						atCommand = "AT+VER=?";

                  Debug.WriteLine("");
						Debug.WriteLine($"{i} TX:{atCommand} bytes:{atCommand.Length}--------------------------------");
						_SerialPort.WriteLine(atCommand);

						Thread.Sleep(5000);
					}
				}
				Debug.WriteLine("Done");
			}
			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:
					break;

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

#if SERIAL_THREADED_READ
		public static void SerialPortProcessor()
		{

			while (_Continue)
			{
				try
				{
					string response = _SerialPort.ReadLine();
					//string response = _SerialPort.ReadExisting();
					Debug.Write(response);
				}
				catch (TimeoutException ex) 
				{
					Debug.WriteLine($"Timeout:{ex.Message}");
				}
			}
		}
#endif
	}
}

When I requested the RAK3172 version information with “AT+VER=?” the response was spilt over two lines which is a bit of a Pain in the Arse (PitA). The RAK3172 firmware also defaults 115200 baud which seems overkill considering the throughput of a LoRaWAN link.

Visual Studio Debug Output of Breakout Serial Application

While building the test application I encountered a few issues (STM32F769I DISCOVERY SerialPort.GetPortNames() port name text gets shorter, STM32F769I DISCOVERY Inconsistent SerialPort WatchChar behaviour after erase->power cycle->run & erase->run and No SerialPort.WatchChar events if WatchChar set before SerialPort opened) which slowed down development. The speed the nanoFramework team triages then fixes issues is amazing for a team of volunteers dotted around the world.