.Net Meadow RFM95/96/97/98 LoRa library Part5

Receive Basic

For testing this code I used the same version of the LoRaSetSyncWord example as Transmit Basic

20:57:40.239 -> LoRa init succeeded.
20:57:40.759 -> Sending HeLoRa World! 0
20:57:40.968 -> Message: ⸮LoRaIoT1Maduino2at 57.7,ah 64,wsa 1,wsg 2,wd 88.13,r 0.00,
20:57:41.036 -> RSSI: -72
20:57:41.036 -> Snr: 9.50
20:57:41.036 -> 
20:57:51.766 -> Sending HeLoRa World! 2
20:58:02.532 -> Sending HeLoRa World! 4
20:58:12.845 -> Sending HeLoRa World! 6
20:58:23.434 -> Sending HeLoRa World! 8
20:58:34.190 -> Sending HeLoRa World! 10
20:58:42.005 -> Message: ⸮LoRaIoT1Maduino2at 57.6,ah 64,wsa 2,wsg 5,wd 74.25,r 0.00,
20:58:42.074 -> RSSI: -72
20:58:42.074 -> Snr: 9.75

The Meadow code builds on my Windows 10 IoT Core Receive Basic and the Meadow Transmit Basic samples.

public class MeadowApp : App<F7Micro, MeadowApp>
{
	private Rfm9XDevice rfm9XDevice;

	public MeadowApp()
	{
		ISpiBus spiBus = Device.CreateSpiBus(500);
		if (spiBus == null)
		{
			Console.WriteLine("spiBus == null");
		}

		rfm9XDevice = new Rfm9XDevice(Device, spiBus, Device.Pins.D09, Device.Pins.D11);

		// Put device into LoRa + Sleep mode
		rfm9XDevice.RegisterWriteByte(0x01, 0b10000000); // RegOpMode 

		// Set the frequency to 915MHz
		byte[] frequencyWriteBytes = { 0xE4, 0xC0, 0x00 }; // RegFrMsb, RegFrMid, RegFrLsb
		rfm9XDevice.RegisterWrite(0x06, frequencyWriteBytes);

		rfm9XDevice.RegisterWriteByte(0x0F, 0x0); // RegFifoRxBaseAddress 

		rfm9XDevice.RegisterWriteByte(0x01, 0b10000101); // RegOpMode set LoRa & RxContinuous

		while (true)
		{
			// Wait until a packet is received, no timeouts in PoC
			Console.WriteLine("Receive-Wait");
			byte IrqFlags = rfm9XDevice.RegisterReadByte(0x12); // RegIrqFlags
			while ((IrqFlags & 0b01000000) == 0)  // wait until RxDone cleared
			{
				Task.Delay(100).Wait();
				IrqFlags = rfm9XDevice.RegisterReadByte(0x12); // RegIrqFlags
				Console.Write(".");
			}
			Console.WriteLine("");
			Console.WriteLine(string.Format("RegIrqFlags {0}", Convert.ToString((byte)IrqFlags, 2).PadLeft(8, '0')));
			Console.WriteLine("Receive-Message");
			byte currentFifoAddress = rfm9XDevice.RegisterReadByte(0x10); // RegFifiRxCurrent
			rfm9XDevice.RegisterWriteByte(0x0d, currentFifoAddress); // RegFifoAddrPtr

			byte numberOfBytes = rfm9XDevice.RegisterReadByte(0x13); // RegRxNbBytes

			byte[] messageBytes = rfm9XDevice.RegisterRead(0x00, numberOfBytes); // RegFifo

			rfm9XDevice.RegisterWriteByte(0x0d, 0);
			rfm9XDevice.RegisterWriteByte(0x12, 0b11111111); // RegIrqFlags clear all the bits

			string messageText = UTF8Encoding.UTF8.GetString(messageBytes);
			Console.WriteLine("Received {0} byte message {1}", messageBytes.Length, messageText);

			Console.WriteLine("Receive-Done");
		}
	}
}

The receive code works reliably but has no error detection or correction capability, so every so often a message gets corrupted. Which is can be seen in the Debug output below.

'App.exe' (CLR v4.0.30319: DefaultDomain): Loaded 'C:\WINDOWS\Microsoft.Net\assembly\GAC_64\mscorlib\v4.0_4.0.0.0__b77a5c561934e089\mscorlib.dll'. 
'App.exe' (CLR v4.0.30319: DefaultDomain): Loaded 'C:\Users\BrynLewis\source\repos\RFM9X.Meadow\ReceiveBasic\bin\Debug\net472\App.exe'. Symbols loaded.
'App.exe' (CLR v4.0.30319: App.exe): Loaded 'C:\Users\BrynLewis\source\repos\RFM9X.Meadow\ReceiveBasic\bin\Debug\net472\Meadow.dll'. 
The program '[18208] App.exe: Program Trace' has exited with code 0 (0x0).
The program '[18208] App.exe' has exited with code 0 (0x0).
.
.
DirectRegisterAccess = True
.
.
Receive-Wait
RegIrqFlags 01010000
Receive-Message
Received 61 byte message ???LoRaIoT1Maduino2at 57.7,ah 64,wsa 2,wsg 4,wd 254.25,r 0.00,
Receive-Done
Receive-Wait
RegIrqFlags 01110000
Receive-Message
Received 60 byte message ???LoReE??????!???ngvyno2at,57/7-ah 6???,w???a 2,w?????????6,7$.13,r 0.00-
Receive-Done
Receive-Wait
RegIrqFlags 01010000
Receive-Message
Received 16 byte message HeLoRa World! 0
Receive-Done
Receive-Wait
RegIrqFlags 01000000
Receive-Message
Received 60 byte message ???LoRaIoT1Maduino2at 57.7,ah 64,wsa 1,wsg 2,wd 88.13,r 0.00,
Receive-Done
Receive-Wait
RegIrqFlags 01010000
Receive-Message
Received 16 byte message HeLoRa World! 2
Receive-Done
Receive-Wait

I will look at implementing some sort of carrier-sense multiple access with collision avoidance solution to reduce the number of corrupted messages when two (or possibly more devices) transmit at the same time.

Transmitting/receiving with interrupts or design goals next.

.Net Meadow RFM95/96/97/98 LoRa library Part4

Transmit Basic

I had a couple of Armtronix IA005 SX1276 loRa nodes sitting on my desk from a recent post so I used one of them running a modified version of the Arduino LoRa library LoRaSetSyncWord example to receive messages from my Meadow device.

/*
  LoRa Duplex communication with Sync Word
 
  Sends a message every half second, and polls continually
  for new incoming messages. Sets the LoRa radio's Sync Word.
 
  Spreading factor is basically the radio's network ID. Radios with different
  Sync Words will not receive each other's transmissions. This is one way you
  can filter out radios you want to ignore, without making an addressing scheme.
 
  See the Semtech datasheet, http://www.semtech.com/images/datasheet/sx1276.pdf
  for more on Sync Word.
 
  created 28 April 2017
  by Tom Igoe
*/
#include <stdlib.h>
#include <LoRa.h>
const int csPin = PA4;          // LoRa radio chip select
const int resetPin = PC13;       // LoRa radio reset
const int irqPin = PA11;         // change for your board; must be a hardware interrupt pin
 
byte msgCount = 0;            // count of outgoing messages
int interval = 2000;          // interval between sends
long lastSendTime = 0;        // time of last packet send
 
void setup() {
  Serial.begin(9600);                   // initialize serial
  while (!Serial);
 
  Serial.println("LoRa Duplex - Set sync word");
 
  // override the default CS, reset, and IRQ pins (optional)
  LoRa.setPins(csPin, resetPin, irqPin);// set CS, reset, IRQ pin
 
  if (!LoRa.begin(915E6)) {             // initialize ratio at 915 MHz
    Serial.println("LoRa init failed. Check your connections.");
    while (true);                       // if failed, do nothing
  }
 
  LoRa.setSyncWord(0x12);           // ranges from 0-0xFF, default 0x34, see API docs
 
  LoRa.dumpRegisters(Serial);
  Serial.println("LoRa init succeeded.");
}
 
void loop() {
  if (millis() - lastSendTime > interval) {
    String message = "HeLoRa World! ";   // send a message
    message += msgCount;
    sendMessage(message);
    Serial.println("Sending " + message);
    lastSendTime = millis();            // timestamp the message
    interval = random(1000) + 10000;    // 10-11 seconds
    msgCount++;
  }
 
  // parse for a packet, and call onReceive with the result:
  onReceive(LoRa.parsePacket());
}
 
void sendMessage(String outgoing) {
  LoRa.beginPacket();                   // start packet
  LoRa.print(outgoing);                 // add payload
  LoRa.endPacket();                     // finish packet and send it
  msgCount++;                           // increment message ID
}
 
void onReceive(int packetSize) {
  if (packetSize == 0) return;          // if there's no packet, return
 
  // read packet header bytes:
  String incoming = "";
 
  while (LoRa.available()) {
    incoming += (char)LoRa.read();
  }
 
  Serial.println("Message: " + incoming);
  Serial.println("RSSI: " + String(LoRa.packetRssi()));
  Serial.println("Snr: " + String(LoRa.packetSnr()));
  Serial.println();
}

The Meadow application

	public class MeadowApp : App<F7Micro, MeadowApp>
	{
		private Rfm9XDevice rfm9XDevice;

		public MeadowApp()
		{
			ISpiBus spiBus = Device.CreateSpiBus(500);
			if (spiBus == null)
			{
				Console.WriteLine("spiBus == null");
			}

			rfm9XDevice = new Rfm9XDevice(Device, spiBus, Device.Pins.D09, Device.Pins.D11);

			// Put device into LoRa + Sleep 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

			while (true)
			{
				rfm9XDevice.RegisterWriteByte(0x0E, 0x0); // RegFifoTxBaseAddress 

				// Set the Register Fifo address pointer
				rfm9XDevice.RegisterWriteByte(0x0D, 0x0); // RegFifoAddrPtr 

				string messageText = "Hello LoRa!";

				// load the message into the fifo
				byte[] messageBytes = UTF8Encoding.UTF8.GetBytes(messageText);
				foreach (byte b in messageBytes)
				{
					rfm9XDevice.RegisterWriteByte(0x0, b); // RegFifo
				}

				// Set the length of the message in the fifo
				rfm9XDevice.RegisterWriteByte(0x22, (byte)messageBytes.Length); // RegPayloadLength

				Console.WriteLine("Sending {0} bytes message {1}", messageBytes.Length, messageText);
				/// Set the mode to LoRa + Transmit
				rfm9XDevice.RegisterWriteByte(0x01, 0b10000011); // RegOpMode 

				// Wait until send done, no timeouts in PoC
				Console.WriteLine("Send-wait");
				byte IrqFlags = rfm9XDevice.RegisterReadByte(0x12); // RegIrqFlags
				while ((IrqFlags & 0b00001000) == 0)  // wait until TxDone cleared
				{
					Task.Delay(10).Wait();
					IrqFlags = rfm9XDevice.RegisterReadByte(0x12); // RegIrqFlags
					Console.Write(".");
				}
				Console.WriteLine("");
				rfm9XDevice.RegisterWriteByte(0x12, 0b00001000); // clear TxDone bit
				Console.WriteLine("Send-Done");

				Task.Delay(30000).Wait();
			}
		}

When I ran the meadow application after some messing around with the jumper wires.

'App.exe' (CLR v4.0.30319: DefaultDomain): Loaded 'C:\WINDOWS\Microsoft.Net\assembly\GAC_64\mscorlib\v4.0_4.0.0.0__b77a5c561934e089\mscorlib.dll'. 
'App.exe' (CLR v4.0.30319: DefaultDomain): Loaded 'C:\Users\BrynLewis\source\repos\RFM9X.Meadow\TransmitBasic\bin\Debug\net472\App.exe'. Symbols loaded.
'App.exe' (CLR v4.0.30319: App.exe): Loaded 'C:\Users\BrynLewis\source\repos\RFM9X.Meadow\TransmitBasic\bin\Debug\net472\Meadow.dll'. 
The program '[37572] App.exe: Program Trace' has exited with code 0 (0x0).
The program '[37572] App.exe' has exited with code 0 (0x0).
.
.
DirectRegisterAccess = True
.
.
Sending 11 bytes message Hello LoRa!
Send-wait
Send-Done
Sending 11 bytes message Hello LoRa!
Send-wait
.
Send-Done

I could the see the messages arriving at the Armtronix device in the Arduino monitor (the other messages in the monitor are my solar powered weather station and soil moisture monitoring node).

12:47:55.198 -> Sending HeLoRa World! 10
12:48:05.745 -> Sending HeLoRa World! 12
12:48:06.663 -> Message: ⸮LoRaIoT1Maduino2at 85.8,ah 19,wsa 5,wsg 8,wd 123.38,r 0.00,
12:48:06.730 -> RSSI: -71
12:48:06.730 -> Snr: 10.00
12:48:06.730 ->
12:48:08.770 -> Message: Hello LoRa!
12:48:08.770 -> RSSI: -47
12:48:08.804 -> Snr: 9.00
12:48:08.804 ->
12:48:16.555 -> Sending HeLoRa World! 14
12:48:26.847 -> Sending HeLoRa World! 16
12:48:37.154 -> Sending HeLoRa World! 18
12:48:39.469 -> Message: Hello LoRa!
12:48:39.469 -> RSSI: -46
12:48:39.536 -> Snr: 9.00
12:48:39.536 ->
12:48:47.311 -> Sending HeLoRa World! 20
12:48:58.094 -> Sending HeLoRa World! 22
12:49:07.748 -> Message: ⸮LoRaIoT1Maduino2at 86.0,ah 19,wsa 5,wsg 15,wd 155.63,r 0.00,
12:49:07.817 -> RSSI: -71
12:49:07.817 -> Snr: 9.50
12:49:07.817 ->
12:49:08.464 -> Sending HeLoRa World! 24
12:49:10.097 -> Message: Hello LoRa!
12:49:10.097 -> RSSI: -46
12:49:10.130 -> Snr: 9.75
12:49:10.130 ->
12:49:19.373 -> Sending HeLoRa World! 26
12:49:30.125 -> Sending HeLoRa World! 28
12:49:40.262 -> Sending HeLoRa World! 30
12:49:40.671 -> Message: Hello LoRa!
12:49:40.671 -> RSSI: -46
12:49:40.705 -> Snr: 9.25
12:49:40.705 ->
12:49:50.725 -> Sending HeLoRa World! 32
12:50:01.081 -> Sending HeLoRa World! 34
12:50:08.800 -> Message: ⸮LoRaIoT1Maduino2at 85.6,ah 19,wsa 5,wsg 11,wd 159.00,r 0.00,
12:50:08.868 -> RSSI: -72
12:50:08.868 -> Snr: 10.00
12:50:08.868 ->
12:50:11.219 -> Message: Hello LoRa!
12:50:11.219 -> RSSI: -46
12:50:11.252 -> Snr: 9.25
12:50:11.252 ->
12:50:11.526 -> Sending HeLoRa World! 36
12:50:21.731 -> Sending HeLoRa World! 38
12:50:32.696 -> Sending HeLoRa World! 40
12:50:41.741 -> Message: Hello LoRa!
12:50:41.741 -> RSSI: -46
12:50:41.775 -> Snr: 9.25
12:50:41.775 ->
12:50:43.685 -> Sending HeLoRa World! 42
12:50:54.566 -> Sending HeLoRa World! 44
12:51:05.604 -> Sending HeLoRa World! 46
12:51:09.852 -> Message: ⸮LoRaIoT1Maduino2at 85.3,ah 19,wsa 2,wsg 8,wd 150.75,r 0.00,
12:51:09.954 -> RSSI: -71
12:51:09.954 -> Snr: 9.50
12:51:09.954 ->
12:51:12.400 -> Message: Hello LoRa!
12:51:12.400 -> RSSI: -46
12:51:12.433 -> Snr: 9.00
12:51:12.433 ->
12:51:16.511 -> Sending HeLoRa World! 48
12:51:27.530 -> Sending HeLoRa World! 50
12:51:37.796 -> Sending HeLoRa World! 52
12:51:42.968 -> Message: Hello LoRa!
12:51:42.968 -> RSSI: -45
12:51:43.003 -> Snr: 9.25
12:51:43.003 ->
12:51:48.389 -> Sending HeLoRa World! 54
12:51:59.052 -> Sending HeLoRa World! 56
12:52:09.251 -> Sending HeLoRa World! 58
12:52:10.912 -> Message: ⸮LoRaIoT1Maduino2at 85.1,ah 19,wsa 2,wsg 6,wd 84.00,r 0.00,
12:52:11.013 -> RSSI: -70
12:52:11.013 -> Snr: 9.75
12:52:11.013 ->
12:52:13.546 -> Message: Hello LoRa!
12:52:13.546 -> RSSI: -46
12:52:13.581 -> Snr: 9.75
12:52:13.581 ->

This PoC code is getting a bit nasty with magic numbers and no error checking. The next step is getting a basic packet receive working…

.Net Meadow RFM95/96/97/98 LoRa library Part3

Register Read and Write

Now that I could reliably dump all the Arduino shield registers I wanted to be able to configure the Semtech 1276/7/8/9 device and reset it back to factory settings.

A factory reset is done by strobing the reset pin on the device. To support this my Rfm9XDevice class constructor gained an additional parameter, the reset GPIO pin.

Arduino shield connected to Meadow with jumper wires

To configure the RFM9X I wrote some wrapper functions for the Meadow SPI API to read/write byte values, word values and arrays of bytes. The Meadow APIs (Dec 2019) return an additional byte at the start of each reply (unlike the .NetMF and Windows 10 IoT Core APIs) which has to be removed.

Each method was tested by read/writing suitable register(s) in the device configuration (Needed to set it into LoRa mode first).

//---------------------------------------------------------------------------------
// Copyright (c) December 2019, 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.ReadAndWrite
{
   using System;
    using System.Diagnostics;
    using System.Runtime.InteropServices.WindowsRuntime;
    using System.Threading.Tasks;

   using Meadow;
   using Meadow.Devices;
   using Meadow.Hardware;

   public sealed class Rfm9XDevice
   {
      private SpiPeripheral Rfm9XLoraModem;
      private IDigitalOutputPort ChipSelectGpioPin;
		private const byte RegisterAddressReadMask = 0X7f;
		private const byte RegisterAddressWriteMask = 0x80;

		public Rfm9XDevice(IIODevice device, ISpiBus spiBus, IPin chipSelectPin, IPin resetPin)
      {
         // Chip select pin configuration
         ChipSelectGpioPin = device.CreateDigitalOutputPort(chipSelectPin, initialState: true);
         if (ChipSelectGpioPin == null)
         {
            Console.WriteLine("ChipSelectGpioPin == null");
         }

         // Factory reset pin configuration
         IDigitalOutputPort resetGpioPin = device.CreateDigitalOutputPort(resetPin);
         if (resetGpioPin == null)
         {
            Console.WriteLine("resetGpioPin == null");
         }
         resetGpioPin.State = false;
         Task.Delay(10);
         resetGpioPin.State = true;
         Task.Delay(10);

			Rfm9XLoraModem = new SpiPeripheral(spiBus, ChipSelectGpioPin);
         if (Rfm9XLoraModem == null)
         {
            Console.WriteLine("Rfm9XLoraModem == null");
         }
      }

      public Byte RegisterReadByte(byte address)
      {
         byte[] writeBuffer = new byte[] { address &= RegisterAddressReadMask };
			Debug.Assert(Rfm9XLoraModem != null);

			byte[] readBuffer = Rfm9XLoraModem.WriteRead(writeBuffer, 2);

         return readBuffer[1];
      }

		public ushort RegisterReadWord(byte address)
		{
			byte[] writeBuffer = new byte[] { address &= RegisterAddressReadMask };
			Debug.Assert(Rfm9XLoraModem != null);

			byte[] readBuffer = Rfm9XLoraModem.WriteRead(writeBuffer, 3);

			return (ushort)(readBuffer[2] + (readBuffer[1] << 8));
		}

		public byte[] RegisterRead(byte address, int length)
		{
			byte[] writeBuffer = new byte[] { address &= RegisterAddressReadMask };
			byte[] repyBuffer = new byte[length + 1];
			Debug.Assert(Rfm9XLoraModem != null);

			byte[] readBuffer = Rfm9XLoraModem.WriteRead(writeBuffer, (ushort)repyBuffer.Length);

			Array.Copy(readBuffer, 1, repyBuffer, 0, length);

			return repyBuffer;
		}

		public void RegisterWriteByte(byte address, byte value)
		{
			byte[] writeBuffer = new byte[] { address |= RegisterAddressWriteMask, value };
			Debug.Assert(Rfm9XLoraModem != null);

			Rfm9XLoraModem.WriteBytes(writeBuffer);
		}

		public void RegisterWriteWord(byte address, ushort value)
		{
			byte[] valueBytes = BitConverter.GetBytes(value);
			byte[] writeBuffer = new byte[] { address |= RegisterAddressWriteMask, valueBytes[0], valueBytes[1] };
			Debug.Assert(Rfm9XLoraModem != null);

			Rfm9XLoraModem.WriteBytes(writeBuffer);
		}
		public void RegisterWrite(byte address, [ReadOnlyArray()] byte[] bytes)
		{
			byte[] writeBuffer = new byte[1 + bytes.Length];
			Debug.Assert(Rfm9XLoraModem != null);

			Array.Copy(bytes, 0, writeBuffer, 1, bytes.Length);
			writeBuffer[0] = address |= RegisterAddressWriteMask;

			Rfm9XLoraModem.WriteBytes(writeBuffer);
		}

		public void RegisterDump()
		{
			Console.WriteLine("Register dump");
			for (byte registerIndex = 0; registerIndex <= 0x42; registerIndex++)
			{
				byte registerValue = this.RegisterReadByte(registerIndex);

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

	public class MeadowApp : App<F7Micro, MeadowApp>
   {
      private Rfm9XDevice rfm9XDevice;

      public MeadowApp()
      {
			ISpiBus spiBus = Device.CreateSpiBus(500);
         if (spiBus == null)
         {
            Console.WriteLine("spiBus == null");
         }

			rfm9XDevice = new Rfm9XDevice(Device, spiBus, Device.Pins.D09, Device.Pins.D11);

			while (true)
         {
				rfm9XDevice.RegisterDump();

				Byte regOpMode = rfm9XDevice.RegisterReadByte(0x1);

				Console.WriteLine("Set LoRa mode and sleep mode (write byte)");
				rfm9XDevice.RegisterWriteByte(0x01, 0b10000000); // 

				Console.WriteLine("Read the preamble (read word)");
				ushort preamble = rfm9XDevice.RegisterReadWord(0x20);
				Console.WriteLine("Preamble 0x{0:x2} - Bits {1}", preamble, Convert.ToString(preamble, 2).PadLeft(16, '0'));

				Console.WriteLine("Set the preamble to 0x80 (write word)");
				rfm9XDevice.RegisterWriteWord(0x20, 0x80);

				Console.WriteLine("Read the centre frequency (read byte array)");
				byte[] frequencyReadBytes = rfm9XDevice.RegisterRead(0x06, 3);
				Console.WriteLine("Frequency Msb 0x{0:x2} Mid 0x{1:x2} Lsb 0x{2:x2}", frequencyReadBytes[0], frequencyReadBytes[1], frequencyReadBytes[2]);

				Console.WriteLine("Set the centre frequency to 916MHz ( write byte array)");
				byte[] frequencyWriteBytes = { 0xE4, 0xC0, 0x00 };
				rfm9XDevice.RegisterWrite(0x06, frequencyWriteBytes);

				rfm9XDevice.RegisterDump();

				Task.Delay(30000).Wait();
			}
		}
   }
}

The output of the application looked like this

'App.exe' (CLR v4.0.30319: DefaultDomain): Loaded 'C:\WINDOWS\Microsoft.Net\assembly\GAC_64\mscorlib\v4.0_4.0.0.0__b77a5c561934e089\mscorlib.dll'. 
'App.exe' (CLR v4.0.30319: DefaultDomain): Loaded 'C:\Users\BrynLewis\source\repos\RFM9X.Meadow\RegisterReadAndWrite\bin\Debug\net472\App.exe'. Symbols loaded.
'App.exe' (CLR v4.0.30319: App.exe): Loaded 'C:\Users\BrynLewis\source\repos\RFM9X.Meadow\RegisterReadAndWrite\bin\Debug\net472\Meadow.dll'. 
The program '[31296] App.exe: Program Trace' has exited with code 0 (0x0).
The program '[31296] App.exe' has exited with code 0 (0x0).
.
.
DirectRegisterAccess = True
==========================================================
Ignore the exceptions generated by the DateTime call here.
==========================================================
.
Register dump
.
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 0X00 - Bits 00000000
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
Set LoRa mode and sleep mode (write byte)
Read the preamble (read word)
Preamble 0x08 - Bits 0000000000001000
Set the preamble to 0x80 (write word)
Read the centre frequency (read byte array)
Frequency Msb 0x6c Mid 0x80 Lsb 0x00
Set the centre frequency to 916MHz ( write byte array)
Register dump
Register 0x00 - Value 0Xf4 - Bits 11110100
Register 0x01 - Value 0X80 - Bits 10000000
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 0Xe4 - Bits 11100100
Register 0x07 - Value 0Xc0 - Bits 11000000
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 0X02 - Bits 00000010
Register 0x0e - Value 0X80 - Bits 10000000
Register 0x0f - Value 0X00 - Bits 00000000
Register 0x10 - Value 0X00 - Bits 00000000
Register 0x11 - Value 0X00 - Bits 00000000
Register 0x12 - Value 0X00 - Bits 00000000
Register 0x13 - Value 0X00 - Bits 00000000
Register 0x14 - Value 0X00 - Bits 00000000
Register 0x15 - Value 0X00 - Bits 00000000
Register 0x16 - Value 0X00 - Bits 00000000
Register 0x17 - Value 0X00 - Bits 00000000
Register 0x18 - Value 0X10 - Bits 00010000
Register 0x19 - Value 0X00 - Bits 00000000
Register 0x1a - Value 0X00 - Bits 00000000
Register 0x1b - Value 0X00 - Bits 00000000
Register 0x1c - Value 0X00 - Bits 00000000
Register 0x1d - Value 0X72 - Bits 01110010
Register 0x1e - Value 0X70 - Bits 01110000
Register 0x1f - Value 0X64 - Bits 01100100
Register 0x20 - Value 0X80 - Bits 10000000
Register 0x21 - Value 0X00 - Bits 00000000
Register 0x22 - Value 0X01 - Bits 00000001
Register 0x23 - Value 0Xff - Bits 11111111
Register 0x24 - Value 0X00 - Bits 00000000
Register 0x25 - Value 0X00 - Bits 00000000
Register 0x26 - Value 0X04 - Bits 00000100
Register 0x27 - Value 0X00 - Bits 00000000
Register 0x28 - Value 0X00 - Bits 00000000
Register 0x29 - Value 0X00 - Bits 00000000
Register 0x2a - Value 0X00 - Bits 00000000
Register 0x2b - Value 0X00 - Bits 00000000
Register 0x2c - Value 0X00 - Bits 00000000
Register 0x2d - Value 0X50 - Bits 01010000
Register 0x2e - Value 0X14 - Bits 00010100
Register 0x2f - Value 0X45 - Bits 01000101
Register 0x30 - Value 0X55 - Bits 01010101
Register 0x31 - Value 0Xc3 - Bits 11000011
Register 0x32 - Value 0X05 - Bits 00000101
Register 0x33 - Value 0X27 - Bits 00100111
Register 0x34 - Value 0X1c - Bits 00011100
Register 0x35 - Value 0X0a - Bits 00001010
Register 0x36 - Value 0X03 - Bits 00000011
Register 0x37 - Value 0X0a - Bits 00001010
Register 0x38 - Value 0X42 - Bits 01000010
Register 0x39 - Value 0X12 - Bits 00010010
Register 0x3a - Value 0X49 - Bits 01001001
Register 0x3b - Value 0X1d - Bits 00011101
Register 0x3c - Value 0X00 - Bits 00000000
Register 0x3d - Value 0Xaf - Bits 10101111
Register 0x3e - Value 0X00 - Bits 00000000
Register 0x3f - Value 0X00 - Bits 00000000
Register 0x40 - Value 0X00 - Bits 00000000
Register 0x41 - Value 0X00 - Bits 00000000
Register 0x42 - Value 0X12 - Bits 00010010

The next step is to extract the SPI register access functionality into a module and configure the bare minimum of settings required to get the RFM9X to transmit.

.Net Meadow RFM95/96/97/98 LoRa library Part2

Register Dump

Next step was to dump all registers (0x00 thru 0x42) of the SX1276/7/8/9 device

//---------------------------------------------------------------------------------
// Copyright (c) December 2019, 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.RegisterScan
{
   using System;
   using System.Threading.Tasks;

   using Meadow;
   using Meadow.Devices;
   using Meadow.Hardware;

   public sealed class Rfm9XDevice
   {
      private SpiPeripheral sx127xDevice;
      private IDigitalOutputPort spiPeriphChipSelect;

      public Rfm9XDevice(IIODevice device, ISpiBus spiBus, IPin chipSelectPin)
      {
         spiPeriphChipSelect = device.CreateDigitalOutputPort(chipSelectPin, initialState: true);
         if (spiPeriphChipSelect == null)
         {
            Console.WriteLine("spiPeriphChipSelect == null");
         }

         sx127xDevice = new SpiPeripheral(spiBus, spiPeriphChipSelect);
         if (sx127xDevice == null)
         {
            Console.WriteLine("sx127xDevice == null");
         }
      }

      public Byte RegisterReadByte(byte registerAddress)
      {
         byte[] txBuffer = new byte[] { registerAddress };

         byte[] rxBuffer = sx127xDevice.WriteRead(txBuffer, 2);

         return rxBuffer[1];
      }
   }

   public class MeadowApp : App<F7Micro, MeadowApp>
   {
      private Rfm9XDevice rfm9XDevice;

      public MeadowApp()
      {
         ISpiBus spiBus = Device.CreateSpiBus(500);
         if (spiBus == null)
         {
            Console.WriteLine("spiBus == null");
         }

         rfm9XDevice = new Rfm9XDevice(Device, spiBus, Device.Pins.D09);

         while (true)
         {
            for (byte registerIndex = 0; registerIndex <= 0x42; registerIndex++)
            {
               byte registerValue = rfm9XDevice.RegisterReadByte(registerIndex);

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

            Task.Delay(10000).Wait();
         }
      }
   }
}

The output of the application looked like this

'App.exe' (CLR v4.0.30319: DefaultDomain): Loaded 'C:\WINDOWS\Microsoft.Net\assembly\GAC_64\mscorlib\v4.0_4.0.0.0__b77a5c561934e089\mscorlib.dll'. 
'App.exe' (CLR v4.0.30319: DefaultDomain): Loaded 'C:\Users\BrynLewis\source\repos\RFM9X.Meadow\RegisterScan\bin\Debug\net472\App.exe'. Symbols loaded.
'App.exe' (CLR v4.0.30319: App.exe): Loaded 'C:\Users\BrynLewis\source\repos\RFM9X.Meadow\RegisterScan\bin\Debug\net472\Meadow.dll'. 
The program '[3148] App.exe: Program Trace' has exited with code 0 (0x0).
The program '[3148] App.exe' has exited with code 0 (0x0).
.
.
DirectRegisterAccess = True
==========================================================
Ignore the exceptions generated by the DateTime call here.
==========================================================
.
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 0X71 - Bits 01110001
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 0Xfd - Bits 11111101
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

I also started to refactor the code, passing the Meadow IIODevice & ISpiBus into the constructor, and extracting the Read functionality.

The device was not in LoRa mode (Bit 7 of RegOpMode 0x01) so the next step was to read and write registers so I could change its configuration.

Windows 10 IoT Core Cognitive Services Azure IoT Hub Client

This application builds on Windows 10 IoT Core Cognitive Services Vision API client. It uses my Lego brick classifier model and a new m&m object detection model.

m&m counter test rig

I created a new Visual Studio 2017 Windows IoT Core project and copied across the Windows 10 IoT Core Cognitive Services Custom Vision API code, (changing the namespace and manifest details) and added the Azure Devices Client NuGet package.

Azure Devices Client NuGet

In the start up code I added code to initialise the Azure IoT Hub client, retrieve the device twin settings, and update the device twin properties.

try
{
	this.azureIoTHubClient = DeviceClient.CreateFromConnectionString(this.azureIoTHubConnectionString, this.transportType);
}
catch (Exception ex)
{
	this.logging.LogMessage("AzureIOT Hub DeviceClient.CreateFromConnectionString failed " + ex.Message, LoggingLevel.Error);
	return;
}

try
{
	TwinCollection reportedProperties = new TwinCollection();

	// This is from the OS
	reportedProperties["Timezone"] = TimeZoneSettings.CurrentTimeZoneDisplayName;
	reportedProperties["OSVersion"] = Environment.OSVersion.VersionString;
	reportedProperties["MachineName"] = Environment.MachineName;

	reportedProperties["ApplicationDisplayName"] = package.DisplayName;
	reportedProperties["ApplicationName"] = packageId.Name;
	reportedProperties["ApplicationVersion"] = string.Format($"{version.Major}.{version.Minor}.{version.Build}.{version.Revision}");

	// Unique identifier from the hardware
	SystemIdentificationInfo systemIdentificationInfo = SystemIdentification.GetSystemIdForPublisher();
	using (DataReader reader = DataReader.FromBuffer(systemIdentificationInfo.Id))
	{
		byte[] bytes = new byte[systemIdentificationInfo.Id.Length];
		reader.ReadBytes(bytes);
		reportedProperties["SystemId"] = BitConverter.ToString(bytes);
	}
	this.azureIoTHubClient.UpdateReportedPropertiesAsync(reportedProperties).Wait();
}
catch (Exception ex)
{
	this.logging.LogMessage("Azure IoT Hub client UpdateReportedPropertiesAsync failed " + ex.Message, LoggingLevel.Error);
	return;
}

try
{
	LoggingFields configurationInformation = new LoggingFields();

	Twin deviceTwin = this.azureIoTHubClient.GetTwinAsync().GetAwaiter().GetResult();

	if (!deviceTwin.Properties.Desired.Contains("ImageUpdateDue") || !TimeSpan.TryParse(deviceTwin.Properties.Desired["ImageUpdateDue"].value.ToString(), out imageUpdateDue))
	{
		this.logging.LogMessage("DeviceTwin.Properties ImageUpdateDue setting missing or invalid format", LoggingLevel.Warning);
		return;
	}
	configurationInformation.AddTimeSpan("ImageUpdateDue", imageUpdateDue);

	if (!deviceTwin.Properties.Desired.Contains("ImageUpdatePeriod") || !TimeSpan.TryParse(deviceTwin.Properties.Desired["ImageUpdatePeriod"].value.ToString(), out imageUpdatePeriod))
	{
		this.logging.LogMessage("DeviceTwin.Properties ImageUpdatePeriod setting missing or invalid format", LoggingLevel.Warning);
		return;
	}
…
	if (!deviceTwin.Properties.Desired.Contains("DebounceTimeout") || !TimeSpan.TryParse(deviceTwin.Properties.Desired["DebounceTimeout"].value.ToString(), out debounceTimeout))
	{
		this.logging.LogMessage("DeviceTwin.Properties DebounceTimeout setting missing or invalid format", LoggingLevel.Warning);
		return;
	}
				configurationInformation.AddTimeSpan("DebounceTimeout", debounceTimeout);

	this.logging.LogEvent("Configuration settings", configurationInformation);
}
catch (Exception ex)
{
	this.logging.LogMessage("Azure IoT Hub client GetTwinAsync failed or property missing/invalid" + ex.Message, LoggingLevel.Error);
	return;
}

When the digital input (configured in the app.settings file) is strobed or the timer fires (configured in the device properties) an image is captured, uploaded to Azure Cognitive Services Custom Vision for processing.

The returned results are then post processed to make them Azure IoT Central friendly, and finally uploaded to an Azure IoT Hub.

For testing I have used a simple object detection model.

I trained the model with images of 6 different colours of m&m’s.

For my first dataset I tagged the location of a single m&m of each of the colour in 15 images.

Testing the training of the model

I then trained the model multiple times adding additional images where the model was having trouble distiguishing colours.

The published name comes from the training performance tab

Project settings

The projectID, AzureCognitiveServicesSubscriptionKey (PredictionKey) and PublishedName (From the Performance tab in project) are from the custom vision project properties.

All of the Custom Vision model settings are configured in the Azure IoT Hub device properties.

The app.settings file contains only the hardware configuration settings and the Azure IoT Hub connection string.

{
  "InterruptPinNumber": 24,
  "interruptTriggerOn": "RisingEdge",
  "DisplayPinNumber": 35,
  "AzureIoTHubConnectionString": "",
  "TransportType": "Mqtt"
} 

The LED connected to the display pin is illuminated while an image is being processed or briefly flashed if the insufficient time between image captures has passed.

The image data is post processed differently based on the model.

// Post process the predictions based on the type of model
switch (modelType)
{
	case ModelType.Classification:
		// Use only the tags above the specified minimum probability
		foreach (var prediction in imagePrediction.Predictions)
		{
			if (prediction.Probability >= probabilityThreshold)
			{
				// Display and log the individual tag probabilities
				Debug.WriteLine($" Tag valid:{prediction.TagName} {prediction.Probability:0.00}");
				imageInformation.AddDouble($"Tag valid:{prediction.TagName}", prediction.Probability);
					telemetryDataPoint.Add(prediction.TagName, prediction.Probability);
			}
		}
		break;

	case ModelType.Detection:
		// Group the tags to get the count, include only the predictions above the specified minimum probability
		var groupedPredictions = from prediction in imagePrediction.Predictions
										 where prediction.Probability >= probabilityThreshold
										 group prediction by new { prediction.TagName }
				into newGroup
										 select new
										 {
											 TagName = newGroup.Key.TagName,
											 Count = newGroup.Count(),
										 };

		// Display and log the agregated predictions
		foreach (var prediction in groupedPredictions)
		{
			Debug.WriteLine($" Tag valid:{prediction.TagName} {prediction.Count}");
			imageInformation.AddInt32($"Tag valid:{prediction.TagName}", prediction.Count);
			telemetryDataPoint.Add(prediction.TagName, prediction.Count);
		}
		break;
	default:
		throw new ArgumentException("ModelType Invalid");
}

For a classifier only the tags with a probability greater than or equal the specified threshold are uploaded.

For a detection model the instances of each tag are counted. Only the tags with a prediction value greater than the specified threshold are included in the count.

19-08-14 05:26:14 Timer triggered
Prediction count 33
 Tag:Blue 0.0146500813
 Tag:Blue 0.61186564
 Tag:Blue 0.0923164859
 Tag:Blue 0.7813785
 Tag:Brown 0.0100603029
 Tag:Brown 0.128318727
 Tag:Brown 0.0135991769
 Tag:Brown 0.687322736
 Tag:Brown 0.846672833
 Tag:Brown 0.1826635
 Tag:Brown 0.0183384717
 Tag:Green 0.0200069249
 Tag:Green 0.367765248
 Tag:Green 0.011428359
 Tag:Orange 0.678825438
 Tag:Orange 0.03718319
 Tag:Orange 0.8643157
 Tag:Orange 0.0296728313
 Tag:Red 0.02141669
 Tag:Red 0.7183208
 Tag:Red 0.0183610674
 Tag:Red 0.0130951973
 Tag:Red 0.82097
 Tag:Red 0.0618815944
 Tag:Red 0.0130757084
 Tag:Yellow 0.04150853
 Tag:Yellow 0.0106579047
 Tag:Yellow 0.0210028365
 Tag:Yellow 0.03392527
 Tag:Yellow 0.129197285
 Tag:Yellow 0.8089519
 Tag:Yellow 0.03723789
 Tag:Yellow 0.74729687
 Tag valid:Blue 2
 Tag valid:Brown 2
 Tag valid:Orange 2
 Tag valid:Red 2
 Tag valid:Yellow 2
 05:26:17 AzureIoTHubClient SendEventAsync start
 05:26:18 AzureIoTHubClient SendEventAsync finish

The debugging output of the application includes the different categories identified in the captured image.

I found my small model was pretty good at detection of individual m&m as long as the ambient lighting was consistent, and the background fairly plain.

Sample image from test rig

Every so often the camera contrast setting went bad and could only be restored by restarting the device which needs further investigation.

Image with contrast problem

This application could be the basis for projects which need to run an Azure Cognitive Services model to count or classify then upload the results to an Azure IoT Hub or Azure IoT Central for presentation.

With a suitable model this application could be used to count the number of people in a room, which could be displayed along with the ambient temperature, humidity, CO2, and noise levels in Azure IoT Central.

The code for this application is available In on GitHub.

Windows 10 IoT Core Cognitive Services Custom Vision API

This application was inspired by one of teachers I work with wanting to count ducks in the stream on the school grounds. The school was having problems with water quality and the they wanted to see if the number of ducks was a factor. (Manually counting the ducks several times a day would be impractical).

I didn’t have a source of training images so built an image classifier using my son’s Lego for testing. In a future post I will build an object detection model once I have some sample images of the stream captured by my Windows 10 IoT Core time lapse camera application.

To start with I added the Azure Cognitive Services Custom Vision API NuGet packages to a new Visual Studio 2017 Windows IoT Core project.

Azure Custom Vision Service NuGet packacges

Then I initialised the Computer Vision API client

try
{
	this.customVisionClient = new CustomVisionPredictionClient(new System.Net.Http.DelegatingHandler[] { })
	{
		ApiKey = this.azureCognitiveServicesSubscriptionKey,
		Endpoint = this.azureCognitiveServicesEndpoint,
	};
}
catch (Exception ex)
{
	this.logging.LogMessage("Azure Cognitive Services Custom Vision Client configuration failed " + ex.Message, LoggingLevel.Error);
	return;
}

Every time the digital input is strobed by the infra red proximity sensor or touch button an image is captured, uploaded for processing, and results displayed in the debug output.

For testing I have used a simple multiclass classifier that I trained with a selection of my son’s Lego. I tagged the brick size height x width x length (1x2x3, smallest of width/height first) and colour (red, green, blue etc.)

Azure Cognitive Services Classifier project creation
Custom vision projects
Lego classifier project properties

The projectID, AzureCognitiveServicesSubscriptionKey (PredictionKey) and PublishedName (From the Performance tab in project) in the app.settings file come from the custom vision project properties.

{
  "InterruptPinNumber": 24,
  "interruptTriggerOn": "RisingEdge",
  "DisplayPinNumber": 35,
  "AzureCognitiveServicesEndpoint": "https://australiaeast.api.cognitive.microsoft.com",
  "AzureCognitiveServicesSubscriptionKey": "41234567890123456789012345678901s,
  "DebounceTimeout": "00:00:30",
  "PublishedName": "LegoBrickClassifierV3",
  "TriggerTag": "1x2x4",
  "TriggerThreshold": "0.4",
  "ProjectID": "c1234567-abcdefghijklmn-1234567890ab"
} 

The sample application only supports one trigger tag + probability and if this condition satisfied the Light Emitting Diode (LED) is turned on for 5 seconds. If an image is being processed or the minimum period between images has not passed the LED is illuminated for 5 milliseconds .

private async void InterruptGpioPin_ValueChanged(GpioPin sender, GpioPinValueChangedEventArgs args)
{
	DateTime currentTime = DateTime.UtcNow;
	Debug.WriteLine($"Digital Input Interrupt {sender.PinNumber} triggered {args.Edge}");

	if (args.Edge != this.interruptTriggerOn)
	{
		return;
	}

	// Check that enough time has passed for picture to be taken
	if ((currentTime - this.imageLastCapturedAtUtc) < this.debounceTimeout)
	{
		this.displayGpioPin.Write(GpioPinValue.High);
		this.displayOffTimer.Change(this.timerPeriodDetectIlluminated, this.timerPeriodInfinite);
		return;
	}

	this.imageLastCapturedAtUtc = currentTime;

	// Just incase - stop code being called while photo already in progress
	if (this.cameraBusy)
	{
		this.displayGpioPin.Write(GpioPinValue.High);
		this.displayOffTimer.Change(this.timerPeriodDetectIlluminated, this.timerPeriodInfinite);
		return;
	}

	this.cameraBusy = true;

	try
	{
		using (Windows.Storage.Streams.InMemoryRandomAccessStream captureStream = new Windows.Storage.Streams.InMemoryRandomAccessStream())
		{
			this.mediaCapture.CapturePhotoToStreamAsync(ImageEncodingProperties.CreateJpeg(), captureStream).AsTask().Wait();
			captureStream.FlushAsync().AsTask().Wait();
			captureStream.Seek(0);

			IStorageFile photoFile = await KnownFolders.PicturesLibrary.CreateFileAsync(ImageFilename, CreationCollisionOption.ReplaceExisting);
			ImageEncodingProperties imageProperties = ImageEncodingProperties.CreateJpeg();
			await this.mediaCapture.CapturePhotoToStorageFileAsync(imageProperties, photoFile);

			ImageAnalysis imageAnalysis = await this.computerVisionClient.AnalyzeImageInStreamAsync(captureStream.AsStreamForRead());

			Debug.WriteLine($"Tag count {imageAnalysis.Categories.Count}");

			if (imageAnalysis.Categories.Intersect(this.categoryList, new CategoryComparer()).Any())
			{
				this.displayGpioPin.Write(GpioPinValue.High);

				// Start the timer to turn the LED off
				this.displayOffTimer.Change(this.timerPeriodFaceIlluminated, this.timerPeriodInfinite);
					}

					LoggingFields imageInformation = new LoggingFields();

					imageInformation.AddDateTime("TakenAtUTC", currentTime);
					imageInformation.AddInt32("Pin", sender.PinNumber);
					Debug.WriteLine($"Categories:{imageAnalysis.Categories.Count}");
					imageInformation.AddInt32("Categories", imageAnalysis.Categories.Count);
					foreach (Category category in imageAnalysis.Categories)
					{
						Debug.WriteLine($" Category:{category.Name} {category.Score}");
						imageInformation.AddDouble($"Category:{category.Name}", category.Score);
					}

					this.logging.LogEvent("Captured image processed by Cognitive Services", imageInformation);
				}
			}
			catch (Exception ex)
			{
				this.logging.LogMessage("Camera photo or save failed " + ex.Message, LoggingLevel.Error);
			}
			finally
			{
				this.cameraBusy = false;
			}
		}

		private void TimerCallback(object state)
		{
			this.displayGpioPin.Write(GpioPinValue.Low);
		}

		internal class CategoryComparer : IEqualityComparer<Category>
		{
			public bool Equals(Category x, Category y)
			{
				if (string.Equals(x.Name, y.Name, StringComparison.OrdinalIgnoreCase))
				{
					return true;
				}

				return false;
			}

			public int GetHashCode(Category obj)
			{
				return obj.Name.GetHashCode();
			}
		}

I found my small model was pretty good at tagging images of Lego bricks as long as the ambient lighting was consistent and the background fairly plain.

When tagging many bricks my ability to distinguish pearl light grey, light grey, sand blue and grey bricks was a problem. I should have started with a limited palette (red, green, blue) of colours and shapes for my models while evaluating different tagging approaches.

The debugging output of the application includes the different categories identified in the captured image.

Digital Input Interrupt 24 triggered RisingEdge
Digital Input Interrupt 24 triggered FallingEdge
Prediction count 54
 Tag:Lime 0.529844046
 Tag:1x1x2 0.4441353
 Tag:Green 0.252290249
 Tag:1x1x3 0.1790101
 Tag:1x2x3 0.132092983
 Tag:Turquoise 0.128928885
 Tag:DarkGreen 0.09383947
 Tag:DarkTurquoise 0.08993266
 Tag:1x2x2 0.08145093
 Tag:1x2x4 0.060960535
 Tag:LightBlue 0.0525473
 Tag:MediumAzure 0.04958712
 Tag:Violet 0.04894981
 Tag:SandGreen 0.048463434
 Tag:LightOrange 0.044860106
 Tag:1X1X1 0.0426577441
 Tag:Azure 0.0416654423
 Tag:Aqua 0.0400410332
 Tag:OliveGreen 0.0387720577
 Tag:Blue 0.035169173
 Tag:White 0.03497391
 Tag:Pink 0.0321456343
 Tag:Transparent 0.0246597622
 Tag:MediumBlue 0.0245670844
 Tag:BrightPink 0.0223842952
 Tag:Flesh 0.0221406389
 Tag:Magenta 0.0208457354
 Tag:Purple 0.0188888311
 Tag:DarkPurple 0.0187285
 Tag:MaerskBlue 0.017609369
 Tag:DarkPink 0.0173041821
 Tag:Lavender 0.0162359159
 Tag:PearlLightGrey 0.0152829709
 Tag:1x1x4 0.0133710662
 Tag:Red 0.0122602312
 Tag:Yellow 0.0118704
 Tag:Clear 0.0114340987
 Tag:LightYellow 0.009903331
 Tag:Black 0.00877647
 Tag:BrightLightYellow 0.00871937349
 Tag:Mediumorange 0.0078356415
 Tag:Tan 0.00738664949
 Tag:Sand 0.00713921571
 Tag:Grey 0.00710422
 Tag:Orange 0.00624707434
 Tag:SandBlue 0.006215865
 Tag:DarkGrey 0.00613187673
 Tag:DarkBlue 0.00578308525
 Tag:DarkOrange 0.003790971
 Tag:DarkTan 0.00348462746
 Tag:LightGrey 0.00321317
 Tag:ReddishBrown 0.00304117263
 Tag:LightBluishGrey 0.00273489812
 Tag:Brown 0.00199119

I’m going to run this application repeatedly, adding more images and retraining the model to see how it performs. Once the model is working wll I’ll try downloading it and running it on a device

Custom Vision Test Harness running on my desk

This sample could be used as a basis for projects like this cat door which stops your pet bringing in dead or wounded animals. The model could be trained with tags to indicate whether the cat is carrying a “present” for their human and locking the door if it is.

RFM69 shield library Part2

Register Dump

Next step was to dump all registers (0x00 RegFifo thru 0x4F RegTemp2) of the RFM69HCW device.

/*
    Copyright ® 2019 May devMobile Software, All Rights Reserved

	 MIT License


	 Permission is hereby granted, free of charge, to any person obtaining a copy
	 of this software and associated documentation files (the "Software"), to deal
    in the Software without restriction, including without limitation the rights
	 to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
	 copies of the Software, and to permit persons to whom the Software is
    furnished to do so, subject to the following conditions:

    The above copyright notice and this permission notice shall be included in all
	 copies or substantial portions of the Software.

    THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
	 IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
    FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
	 AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
	 LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
    OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
	 SOFTWARE

	 RegFiFo 0x00 thru RegPacketConfig2 0x3D

*/
namespace devMobile.IoT.Rfm69Hcw.RegisterScan
{
	using System;
	using System.Diagnostics;
	using System.Threading.Tasks;
	using Windows.ApplicationModel.Background;
	using Windows.Devices.Spi;

	public sealed class Rfm69HcwDevice
	{
		private SpiDevice rfm69Hcw;

		public Rfm69HcwDevice(int chipSelectPin)
		{
			SpiController spiController = SpiController.GetDefaultAsync().AsTask().GetAwaiter().GetResult();
			var settings = new SpiConnectionSettings(chipSelectPin)
			{
				ClockFrequency = 500000,
				Mode = SpiMode.Mode0,
			};

			rfm69Hcw = spiController.GetDevice(settings);
		}

		public Byte RegisterReadByte(byte registerAddress)
		{
			byte[] writeBuffer = new byte[] { registerAddress };
			byte[] readBuffer = new byte[1];
			Debug.Assert(rfm69Hcw != null);

			rfm69Hcw.TransferSequential(writeBuffer, readBuffer);

			return readBuffer[0];
		}
	}

	public sealed class StartupTask : IBackgroundTask
	{
		private const int ChipSelectLine = 0;
		private Rfm69HcwDevice rfm69HcwDevice = new Rfm69HcwDevice(ChipSelectLine);

		public void Run(IBackgroundTaskInstance taskInstance)
		{

			while (true)
			{
				for (byte registerIndex = 0; registerIndex <= 0x4F; registerIndex++)
				{
					byte registerValue = rfm69HcwDevice.RegisterReadByte(registerIndex);

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

				Task.Delay(10000).Wait();
			}
		}
	}
}

I checked a selection of values from the Debug output and they matched the defaults in the datasheet e.g. 0x07-RegFrfMsb 0xE4, 0x08-RegFrfMid 0xC0, 0x09-RegFrfLsb 0x00, 0x2C-RegPreamble 0x0, 0x2D-RegPreamble 0x03 and 0x4E-RegTemp1 0x01.

Register 0x00 - Value 0X00 - Bits 00000000
Register 0x01 - Value 0X04 - Bits 00000100
Register 0x02 - Value 0X00 - Bits 00000000
Register 0x03 - Value 0X1a - Bits 00011010
Register 0x04 - Value 0X0b - Bits 00001011
Register 0x05 - Value 0X00 - Bits 00000000
Register 0x06 - Value 0X52 - Bits 01010010
Register 0x07 - Value 0Xe4 - Bits 11100100
Register 0x08 - Value 0Xc0 - Bits 11000000
Register 0x09 - Value 0X00 - Bits 00000000
Register 0x0a - Value 0X41 - Bits 01000001
Register 0x0b - Value 0X40 - Bits 01000000
Register 0x0c - Value 0X02 - Bits 00000010
Register 0x0d - Value 0X92 - Bits 10010010
Register 0x0e - Value 0Xf5 - Bits 11110101
Register 0x0f - Value 0X20 - Bits 00100000
Register 0x10 - Value 0X24 - Bits 00100100
Register 0x11 - Value 0X9f - Bits 10011111
Register 0x12 - Value 0X09 - Bits 00001001
Register 0x13 - Value 0X1a - Bits 00011010
Register 0x14 - Value 0X40 - Bits 01000000
Register 0x15 - Value 0Xb0 - Bits 10110000
Register 0x16 - Value 0X7b - Bits 01111011
Register 0x17 - Value 0X9b - Bits 10011011
Register 0x18 - Value 0X08 - Bits 00001000
Register 0x19 - Value 0X86 - Bits 10000110
Register 0x1a - Value 0X8a - Bits 10001010
Register 0x1b - Value 0X40 - Bits 01000000
Register 0x1c - Value 0X80 - Bits 10000000
Register 0x1d - Value 0X06 - Bits 00000110
Register 0x1e - Value 0X10 - Bits 00010000
Register 0x1f - Value 0X00 - Bits 00000000
Register 0x20 - Value 0X00 - Bits 00000000
Register 0x21 - Value 0X00 - Bits 00000000
Register 0x22 - Value 0X00 - Bits 00000000
Register 0x23 - Value 0X02 - Bits 00000010
Register 0x24 - Value 0Xff - Bits 11111111
Register 0x25 - Value 0X00 - Bits 00000000
Register 0x26 - Value 0X05 - Bits 00000101
Register 0x27 - Value 0X80 - Bits 10000000
Register 0x28 - Value 0X00 - Bits 00000000
Register 0x29 - Value 0Xff - Bits 11111111
Register 0x2a - Value 0X00 - Bits 00000000
Register 0x2b - Value 0X00 - Bits 00000000
Register 0x2c - Value 0X00 - Bits 00000000
Register 0x2d - Value 0X03 - Bits 00000011
Register 0x2e - Value 0X98 - Bits 10011000
Register 0x2f - Value 0X00 - Bits 00000000
Register 0x30 - Value 0X00 - Bits 00000000
Register 0x31 - Value 0X00 - Bits 00000000
Register 0x32 - Value 0X00 - Bits 00000000
Register 0x33 - Value 0X00 - Bits 00000000
Register 0x34 - Value 0X00 - Bits 00000000
Register 0x35 - Value 0X00 - Bits 00000000
Register 0x36 - Value 0X00 - Bits 00000000
Register 0x37 - Value 0X10 - Bits 00010000
Register 0x38 - Value 0X40 - Bits 01000000
Register 0x39 - Value 0X00 - Bits 00000000
Register 0x3a - Value 0X00 - Bits 00000000
Register 0x3b - Value 0X00 - Bits 00000000
Register 0x3c - Value 0X0f - Bits 00001111
Register 0x3d - Value 0X02 - Bits 00000010
Register 0x3e - Value 0X00 - Bits 00000000
Register 0x3f - Value 0X00 - Bits 00000000
Register 0x40 - Value 0X00 - Bits 00000000
Register 0x41 - Value 0X00 - Bits 00000000
Register 0x42 - Value 0X00 - Bits 00000000
Register 0x43 - Value 0X00 - Bits 00000000
Register 0x44 - Value 0X00 - Bits 00000000
Register 0x45 - Value 0X00 - Bits 00000000
Register 0x46 - Value 0X00 - Bits 00000000
Register 0x47 - Value 0X00 - Bits 00000000
Register 0x48 - Value 0X00 - Bits 00000000
Register 0x49 - Value 0X00 - Bits 00000000
Register 0x4a - Value 0X00 - Bits 00000000
Register 0x4b - Value 0X00 - Bits 00000000
Register 0x4c - Value 0X00 - Bits 00000000
Register 0x4d - Value 0X00 - Bits 00000000
Register 0x4e - Value 0X01 - Bits 00000001
Register 0x4f - Value 0X00 - Bits 00000000