After writing my Windows 10 IoT Core RFM9X library and porting it to .NetMF and Wilderness Labs Meadow I figured another port to GHI Electronics TinyCLR-OS on a FEZ device shouldn’t take too long.
To get started I used a Dragino LoRa shield for Arduino which looked compatible with my FEZT18-N and FEZT18-W devices.
The shield uses D10 for chip select, D2 for RFM9X DI0 interrupt and D9 for Reset. The shield ships with the SPI lines configured for ICSP so the three jumpers diagonally across the shield from the antenna connector need to be swapped to the side closest to the edge of the shield.
First step was to confirm I could (using the TinyCLR SPI NuGet library) read a couple of the Semtech SX1276 registers.
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namespace devMobile.IoT.Rfm9x.ShieldSpi
{
using System;
using System.Diagnostics;
using System.Threading;
using GHIElectronics.TinyCLR.Devices.Spi;
using GHIElectronics.TinyCLR.Pins;
class Program
{
static void Main()
{
var settings = new SpiConnectionSettings()
{
ChipSelectType = SpiChipSelectType.Gpio,
ChipSelectLine = FEZ.GpioPin.D10,
Mode = SpiMode.Mode0,
ClockFrequency = 500000,
DataBitLength = 8,
ChipSelectActiveState = false,
};
var controller = SpiController.FromName(FEZ.SpiBus.Spi1);
var device = controller.GetDevice(settings);
Thread.Sleep(500);
while (true)
{
byte register;
byte[] writeBuffer;
byte[] readBuffer;
// Silicon Version info
register = 0x42; // RegVersion expecting 0x12
// Frequency
//register = 0x06; // RegFrfMsb expecting 0x6C
//register = 0x07; // RegFrfMid expecting 0x80
//register = 0x08; // RegFrfLsb expecting 0x00
//register = 0x17; //RegPayoadLength expecting 0x47
// Preamble length
//register = 0x18; // RegPreambleMsb expecting 0x32
//register = 0x19; // RegPreambleLsb expecting 0x3E
writeBuffer = new byte[] { register, 0x0 };
readBuffer = new byte[writeBuffer.Length];
device.TransferFullDuplex(writeBuffer, readBuffer);
Debug.WriteLine("Value = 0x" + BytesToHexString(readBuffer));
Thread.Sleep(1000);
}
}
private static string BytesToHexString(byte[] bytes)
{
string hexString = string.Empty;
// Create a character array for hexidecimal conversion.
const string hexChars = "0123456789ABCDEF";
// Loop through the bytes.
for (byte b = 0; b < bytes.Length; b++)
{
if (b > 0)
hexString += "-";
// Grab the top 4 bits and append the hex equivalent to the return string.
hexString += hexChars[bytes[b] >> 4];
// Mask off the upper 4 bits to get the rest of it.
hexString += hexChars[bytes[b] & 0x0F];
}
return hexString;
}
}
}
After trying many permutations of settings I could successfully read the RegVersion and default frequency values
The debugging target runtime is loading the application assemblies and starting execution.
Ready.
'GHIElectronics.TinyCLR.VisualStudio.ProjectSystem.dll' (Managed): Loaded 'C:\Users\BrynLewis\source\repos\RFM9X.TinyCLR\ShieldSPI\bin\Debug\pe\..\GHIElectronics.TinyCLR.Native.dll'
'GHIElectronics.TinyCLR.VisualStudio.ProjectSystem.dll' (Managed): Loaded 'C:\Users\BrynLewis\source\repos\RFM9X.TinyCLR\ShieldSPI\bin\Debug\pe\..\GHIElectronics.TinyCLR.Devices.Gpio.dll'
'GHIElectronics.TinyCLR.VisualStudio.ProjectSystem.dll' (Managed): Loaded 'C:\Users\BrynLewis\source\repos\RFM9X.TinyCLR\ShieldSPI\bin\Debug\pe\..\GHIElectronics.TinyCLR.Devices.Spi.dll'
'GHIElectronics.TinyCLR.VisualStudio.ProjectSystem.dll' (Managed): Loaded 'C:\Users\BrynLewis\source\repos\RFM9X.TinyCLR\ShieldSPI\bin\Debug\pe\..\ShieldSPI.exe', Symbols loaded.
The thread '<No Name>' (0x2) has exited with code 0 (0x0).
Value = 0x00-12
Value = 0x00-12
Value = 0x00-12
Value = 0x00-12
Overall the SPI implementation felt closer to Windows 10 IoT Core model than expected.
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