While doing yet more stress testing I noticed a couple of odd message go past and a long pause every so often when sending a message in the Visual Studio output window.

I have two Arduino devices sending addressed messages every (both individual and broadcast) to the Adafruit RFM69 HCW Radio Bonnet, on my two Windows 10 IoT Core devices every 100mSec. At the same time the windows 10 devices are sending each other a message every 5 seconds.

To help spot the pauses I added some code to mark any events where there was a significant gap. In this case ” is ASCII character for 0x22 the device address

21:10:30.746 Received To 34 a 23 byte message Hello World ---0x22:236 CRC Ok True
21:10:30.918 Received To 153 a 23 byte message Hello World ---0x99:236 CRC Ok True
21:10:31.399 Received To 34 a 23 byte message Hello World ---0x22:237 CRC Ok True
21:10:31.568 Send-hello world RFM69-915-01 09-10-31
21:10:31.580 Send-Done
21:10:31.592 Received To 34 a 33 byte message """"""""""""""""""""""""""""""""" CRC Ok True
RC-------------------------------------------
21:10:32.052 Received To 34 a 23 byte message Hello World ---0x22:238 CRC Ok True
21:10:32.225 Received To 153 a 23 byte message Hello World ---0x99:238 CRC Ok True
21:10:32.705 Received To 34 a 23 byte message Hello World ---0x22:239 CRC Ok True

There were also still some corrupted messages

21:10:30.746 Received To 34 a 23 byte message Hello World ---0x22:236 CRC Ok True
21:10:30.918 Received To 153 a 23 byte message Hello World ---0x99:236 CRC Ok True
21:10:31.399 Received To 34 a 23 byte message Hello World ---0x22:237 CRC Ok True
21:10:31.568 Send-hello world RFM69-915-01 09-10-31
21:10:31.580 Send-Done
21:10:31.592 Received To 34 a 33 byte message """"""""""""""""""""""""""""""""" CRC Ok True
RC-------------------------------------------
21:10:32.052 Received To 34 a 23 byte message Hello World ---0x22:238 CRC Ok True
21:10:32.225 Received To 153 a 23 byte message Hello World ---0x99:238 CRC Ok True
21:10:32.705 Received To 34 a 23 byte message Hello World ---0x22:239 CRC Ok True

It looks like if the base station receives a message as it is about to send a message the Rfm69Device_OnTransmit never gets called.

It also looks like every so often the transmitter gets stuck on one of Windows 10 devices effectively jamming the frequency.

Transmit stuck on
16:12:10.193 Received To 34 a 22 byte message Hello World ---0x22:65 CRC Ok True
16:12:10.360 Received To 153 a 22 byte message Hello World ---0x99:65 CRC Ok True
16:12:10.831 Received To 34 a 22 byte message Hello World ---0x22:66 CRC Ok True
16:12:10.998 Received To 153 a 22 byte message Hello World ---0x99:66 CRC Ok True
The thread 0x570 has exited with code 0 (0x0).
16:12:11.484 Send-hello world RFM69-915-01 04-12-11
16:12:11.494 Received To 34 a 22 byte message Hello World ---0x22:67 CRC Ok True
16:12:11.504 Send-Done
The thread 0x3a8 has exited with code 0 (0x0).
16:12:16.554 Send-hello world RFM69-915-01 04-12-16
16:12:16.566 Send-Done
16:12:16.660 Transmit-Done
T--------------------------------------------
16:12:16.736 Received To 153 a 22 byte message Hello World ---0x99:75 CRC Ok True
16:12:17.206 Received To 34 a 22 byte message Hello World ---0x22:76 CRC Ok True
16:12:17.374 Received To 153 a 22 byte message Hello World ---0x99:76 CRC Ok True
16:12:18.011 Received To 153 a 22 byte message Hello World ---0x99:77 CRC Ok True


Transmit stuck 
16:12:07.591 Transmit-Done
16:12:07.880 Received To 153 a 23 byte message Hello World ---0x99:137 CRC Ok True
16:12:08.533 Received To 153 a 23 byte message Hello World ---0x99:138 CRC Ok True
16:12:08.839 Received To 17 a 24 byte message Hello World ----0x11:139 CRC Ok True
16:12:09.186 Received To 153 a 23 byte message Hello World ---0x99:139 CRC Ok True
16:12:09.493 Received To 17 a 24 byte message Hello World ----0x11:140 CRC Ok True
16:12:10.799 Received To 17 a 24 byte message Hello World ----0x11:142 CRC Ok True
The thread 0xc8 has exited with code 0 (0x0).
16:12:12.567 Send-hello world RFM69-915-02 04-12-12
16:12:12.589 Send-Done
16:12:12.681 Transmit-Done
16:12:16.510 Received To 17 a 33 byte message hello world RFM69-915-01 04-12-16 CRC Ok True
16:12:16.576 Received To 153 a 22 byte message Hello World ---0x99:75 CRC Ok True
16:12:17.025 Received To 153 a 23 byte message Hello World ---0x99:151 CRC Ok True
16:12:17.214 Received To 153 a 22 byte message Hello World ---0x99:76 CRC Ok True
16:12:17.331 Received To 17 a 24 byte message Hello World ----0x11:152 CRC Ok True
The thread 0xfa0 has exited with code 0 (0x0).
16:12:17.661 Send-hello world RFM69-915-02 04-12-17
16:12:17.680 Send-Done
16:12:17.772 Transmit-Done
16:12:17.851 Received To 153 a 22 byte message Hello World ---0x99:77 CRC Ok True
16:12:18.331 Received To 153 a 23 byte message Hello World ---0x99:153 CRC Ok True
16:12:18.489 Received To 153 a 22 byte message Hello World ---0x99:78 CRC Ok True
16:12:18.638 Received To 17 a 24 byte message Hello World ----0x11:154 CRC Ok True
16:12:18.985 Received To 153 a 23 byte message Hello World ---0x99:154 CRC Ok True
16:12:19.291 Received To 17 a 24 byte message Hello World ----0x11:155 CRC Ok True
16:12:19.638 Received To 153 a 23 byte message Hello World ---0x99:155 CRC Ok True
16:12:19.944 Received To 17 a 24 byte message Hello World ----0x11:156 CRC Ok True
16:12:20.291 Received To 153 a 23 byte message Hello World ---0x99:156 CRC Ok True
16:12:20.597 Received To 17 a 24 byte message Hello World ----0x11:157 CRC Ok True

Then as rfm69Device.SetMode(Rfm69HcwDevice.RegOpModeMode.Receive) hasn’t been called no messages are received until another message is sent.

It looks like a timing issue around access to the message fifo (I have that in a critical section) so I need todo some more debugging. Maybe purging the receive buffer

byte regPacketConfig2 = RegisterManager.ReadByte((byte)Rfm69HcwDevice.Registers.RegPacketConfig2);
			regPacketConfig2 |= 0b00000100;
			RegisterManager.WriteByte((byte)Rfm69HcwDevice.Registers.RegPacketConfig2, regPacketConfig2);

The adfruit.io RFM69 shield has DIO2 which can be used for automode operation which might remove some of the synchronisation issues I am encountering.

While doing some stress testing I noticed an odd message go past in the Visual Studio output window. I had multiple devices sending addressed messages (both individual and broadcast) to the Adafruit RFM69 HCW Radio Bonnet, on my Windows 10 IoT Core device while it was sending a message every 5 seconds.

Received From 153 a 13 byte message Hello World:7
18:43:56.544 RegIrqFlags2 01100110
18:43:56.558 RegIrqFlags1 11011001
18:43:56.575 Address 0X66 01100110
Received From 102 a 15 byte message Hello World:162
The thread 0x254 has exited with code 0 (0x0).
18:43:57.699 Send-hello world 6:43:57 PM
18:43:57.699 RegIrqFlags2 01100110
18:43:57.731 RegIrqFlags1 10000000
18:43:57.747 Address 0X66 01100110
18:43:57.765 Send-Done
Received From 102 a 15 byte message Hello Woooooooo
18:43:57.987 RegIrqFlags2 00001000
18:43:58.003 RegIrqFlags1 10110000
18:43:58.017 Transmit-Done
Transmit-Done
18:43:58.825 RegIrqFlags2 01100110
18:43:58.838 RegIrqFlags1 11011001
18:43:58.857 Address 0X66 01100110
Received From 102 a 15 byte message Hello World:164
18:43:59.966 RegIrqFlags2 01100110
18:43:59.979 RegIrqFlags1 11011001
18:43:59.998 Address 0X66 01100110

The odd thing was that the RegIrqFlags2 CrcOk (bit 1) was set but the message was still corrupt.

After looking at the code I think the problem was the reading of the received message bytes from the device FIFO and the writing of bytes of message to be transmitted into the device FIFO overlapped. To stop this occurring again I have added code to synchronise access (using a Lock) to the FIFO.

private readonly Object Rfm9XRegFifoLock = new object();
...
private void ProcessPayloadReady(RegIrqFlags1 irqFlags1, RegIrqFlags2 irqFlags2)
{
	byte? address = null;
	byte numberOfBytes;
	byte[] messageBytes;

	lock (Rfm9XRegFifoLock)
	{
		// Read the length of the buffer if variable length packets
		if (PacketFormat == RegPacketConfig1PacketFormat.VariableLength)
		{
			numberOfBytes = RegisterManager.ReadByte((byte)Rfm69HcwDevice.Registers.RegFifo);
		}
		else
		{
			numberOfBytes = PayloadLength;
		}

		// Remove the address from start of the payload
		if (AddressingEnabled)
		{
			address = RegisterManager.ReadByte((byte)Rfm69HcwDevice.Registers.RegFifo);

			Debug.WriteLine("{0:HH:mm:ss.fff} Address 0X{1:X2} {2}", DateTime.Now, address, Convert.ToString((byte)address, 2).PadLeft(8, '0'));
			numberOfBytes--;
		}

		// Allocate a buffer for the payload and read characters from the Fifo
		messageBytes = new byte[numberOfBytes];

		for (int i = 0; i < numberOfBytes; i++)
		{
			messageBytes[i] = RegisterManager.ReadByte((byte)Rfm69HcwDevice.Registers.RegFifo);
		}
	}
...
public void SendMessage(byte[] messageBytes)
{
#region Guard conditions
#endregion

	lock (Rfm9XRegFifoLock)
	{
		SetMode(RegOpModeMode.StandBy);

		if (PacketFormat == RegPacketConfig1PacketFormat.VariableLength)
		{
			RegisterManager.WriteByte((byte)Registers.RegFifo, (byte)messageBytes.Length);
		}

		foreach (byte b in messageBytes)
		{
			this.RegisterManager.WriteByte((byte)Registers.RegFifo, b);
		}

		SetMode(RegOpModeMode.Transmit);
	}
}

The code has been running for a day without any corrupted messages so the lock appears to be working. I can most probably reduce the duration which I hold the lock for but that will require some more stress testing.