TinyCLR OS V2 RC1 RAK811 LoRaWAN library Part2

Nasty OTAA connect

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

EVB plugged into Fezduino

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

I configured the RAK811 module for LoRaWAN

// Set the Working mode to LoRaWAN
txByteCount = serialDevice.Write(UTF8Encoding.UTF8.GetBytes("at+set_config=lora:work_mode:0\r\n"));
Debug.WriteLine($"TX: work mode {txByteCount} bytes");
Thread.Sleep(500);

// Read the response
rxByteCount = serialDevice.BytesToRead;
if (rxByteCount > 0)
{
   byte[] rxBuffer = new byte[rxByteCount];
   serialDevice.Read(rxBuffer);
   Debug.WriteLine($"RX :{UTF8Encoding.UTF8.GetString(rxBuffer)}");
}
...

Then just sequentially step through the necessary configuration to join the TTN network with a suitable delay after each command is sent.

// Set the Region to AS923
txByteCount = serialDevice.Write(UTF8Encoding.UTF8.GetBytes("at+set_config=lora:region:AS923\r\n"));
Debug.WriteLine($"TX: region {txByteCount} bytes");
Thread.Sleep(500);

// Read the response
rxByteCount = serialDevice.BytesToRead;
if (rxByteCount > 0)
{
   byte[] rxBuffer = new byte[rxByteCount];
   serialDevice.Read(rxBuffer);
   Debug.WriteLine($"RX :{UTF8Encoding.UTF8.GetString(rxBuffer)}");
}

// Set the JoinMode
txByteCount = serialDevice.Write(UTF8Encoding.UTF8.GetBytes("at+set_config=lora:join_mode:0\r\n"));
Debug.WriteLine($"TX: join_mode {txByteCount} bytes");
Thread.Sleep(500);

// Read the response
rxByteCount = serialDevice.BytesToRead;
if (rxByteCount > 0)
{
   byte[] rxBuffer = new byte[rxByteCount];
   serialDevice.Read(rxBuffer);
   Debug.WriteLine($"RX :{UTF8Encoding.UTF8.GetString(rxBuffer)}");
}

// OTAA set the devEUI
txByteCount = serialDevice.Write(UTF8Encoding.UTF8.GetBytes($"at+set_config=lora:dev_eui:{DevEui}\r\n"));
Debug.WriteLine($"TX: dev_eui: {txByteCount} bytes");
Thread.Sleep(500);

// Read the response
rxByteCount = serialDevice.BytesToRead;
if (rxByteCount > 0)
{
   byte[] rxBuffer = new byte[rxByteCount];
   serialDevice.Read(rxBuffer);
   Debug.WriteLine($"RX :{UTF8Encoding.UTF8.GetString(rxBuffer)}");
}
...

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

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

TX: region 33 bytes
RX :OK 

TX: join_mode 32 bytes
RX :OK 

TX: dev_eui: 45 bytes
RX :OK 

TX: app_eui 45 bytes
RX :OK 

TX: app_key 61 bytes
RX :OK 

TX: confirm 30 bytes
RX :OK 

TX: join 9 bytes
RX :OK Join Success

TX: send 43 bytes
RX :OK 

TX: send 43 bytes
RX :OK 

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.

Successful OTAA Connect TTN logging

I had some issues with TimeSpan.ToString(…) throwing a CLR_E_UNSUPPORTED_INSTRUCTION exception which has been mentioned on the GHI Forums.

I had to modify my code to fix this issue

Debug.WriteLine($"{DateTime.UtcNow:hh:mm:ss} Join start Timeout:{JoinTimeOut:hh:mm:ss}");

// Became

Debug.WriteLine($" {DateTime.UtcNow:hh:mm:ss} Join Start Timeout {timeout.TotalSeconds} seconds");

I won’t bother with confirming any other functionality as I’m reasonably confident the nanoFramework library (which this code is based on) is working as expected.

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