Transmit Interrupt
Starting with the TransmitBasic sample application I modified the code so that a hardware interrupt (specified in RegDioMapping1) was generated on TxDone (FIFO Payload Transmission completed).
The application inserts a message into the RFM95 transmit FIFO every 10 seconds with confirmation of transmission displayed shortly afterwards
public Rfm9XDevice(int chipSelectPin, int resetPin, int interruptPin)
{
var settings = new SpiConnectionSettings()
{
ChipSelectType = SpiChipSelectType.Gpio,
ChipSelectLine = chipSelectPin,
Mode = SpiMode.Mode0,
ClockFrequency = 500000,
DataBitLength = 8,
ChipSelectActiveState = false,
};
SpiController spiCntroller = SpiController.FromName(FEZ.SpiBus.Spi1);
rfm9XLoraModem = spiCntroller.GetDevice(settings);
// Factory reset pin configuration
GpioController gpioController = GpioController.GetDefault();
GpioPin resetGpioPin = gpioController.OpenPin(resetPin);
resetGpioPin.SetDriveMode(GpioPinDriveMode.Output);
resetGpioPin.Write(GpioPinValue.Low);
Thread.Sleep(10);
resetGpioPin.Write(GpioPinValue.High);
Thread.Sleep(10);
// Interrupt pin for RX message & TX done notification
InterruptGpioPin = gpioController.OpenPin(interruptPin);
resetGpioPin.SetDriveMode(GpioPinDriveMode.Input);
InterruptGpioPin.ValueChanged += InterruptGpioPin_ValueChanged;
}
private void InterruptGpioPin_ValueChanged(GpioPin sender, GpioPinValueChangedEventArgs e)
{
if (e.Edge != GpioPinEdge.RisingEdge)
{
return;
}
byte irqFlags = this.RegisterReadByte(0x12); // RegIrqFlags
Debug.WriteLine($"RegIrqFlags 0X{irqFlags:x2}");
if ((irqFlags & 0b00001000) == 0b00001000) // TxDone
{
Debug.WriteLine("Transmit-Done");
}
this.RegisterWriteByte(0x12, 0xff);// RegIrqFlags
}
…
class Program
{
static void Main()
{
Rfm9XDevice rfm9XDevice = new Rfm9XDevice(FEZ.GpioPin.D10, FEZ.GpioPin.D9, FEZ.GpioPin.D2);
int SendCount = 0;
// 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
// Interrupt on TxDone
rfm9XDevice.RegisterWriteByte(0x40, 0b01000000); // RegDioMapping1 0b00000000 DI0 TxDone
while (true)
{
// Set the Register Fifo address pointer
rfm9XDevice.RegisterWriteByte(0x0E, 0x00); // RegFifoTxBaseAddress
// Set the Register Fifo address pointer
rfm9XDevice.RegisterWriteByte(0x0D, 0x0); // RegFifoAddrPtr
string messageText = $"Hello LoRa {SendCount += 1}!";
// load the message into the fifo
byte[] messageBytes = UTF8Encoding.UTF8.GetBytes(messageText);
rfm9XDevice.RegisterWrite(0x0, messageBytes); // RegFifo
// Set the length of the message in the fifo
rfm9XDevice.RegisterWriteByte(0x22, (byte)messageBytes.Length); // RegPayloadLength
Debug.WriteLine($"Sending {messageBytes.Length} bytes message {messageText}");
rfm9XDevice.RegisterWriteByte(0x01, 0b10000011); // RegOpMode
Thread.Sleep(10000);
}
}
}
The output in the debug window
'GHIElectronics.TinyCLR.VisualStudio.ProjectSystem.dll' (Managed): Loaded 'C:\Users\BrynLewis\source\repos\RFM9X.TinyCLR\TransmitInterrupt\bin\Debug\pe\..\TransmitInterrupt.exe', Symbols loaded.
The thread '<No Name>' (0x2) has exited with code 0 (0x0).
Sending 13 bytes message Hello LoRa 1!
RegIrqFlags 0X08
Transmit-Done
Sending 13 bytes message Hello LoRa 2!
RegIrqFlags 0X08
Transmit-Done
Sending 13 bytes message Hello LoRa 3!
RegIrqFlags 0X08
Transmit-Done
Sending 13 bytes message Hello LoRa 4!
RegIrqFlags 0X08
Transmit-Done
Sending 13 bytes message Hello LoRa 5!
RegIrqFlags 0X08
Transmit-Done
On the Arduino test client the serial monitor displayed
19:39:55.595 -> LoRa init succeeded.
19:39:56.157 -> Sending HeLoRa World! 0
19:39:58.742 -> Message: Hello LoRa 5!
19:39:58.742 -> RSSI: -36
19:39:58.789 -> Snr: 9.50
19:39:58.789 ->
19:40:07.151 -> Sending HeLoRa World! 2
19:40:11.920 -> Message: Hello LoRa 1!
19:40:11.920 -> RSSI: -41
19:40:11.967 -> Snr: 9.75
19:40:11.967 ->
19:40:17.924 -> Sending HeLoRa World! 4
19:40:21.905 -> Message: Hello LoRa 2!
19:40:21.905 -> RSSI: -41
19:40:21.952 -> Snr: 9.50
19:40:21.952 ->
19:40:28.248 -> Sending HeLoRa World! 6
19:40:31.928 -> Message: Hello LoRa 3!
19:40:31.928 -> RSSI: -36
19:40:31.975 -> Snr: 9.50
19:40:31.975 ->
19:40:38.803 -> Sending HeLoRa World! 8
19:40:41.928 -> Message: Hello LoRa 4!
19:40:41.928 -> RSSI: -34
19:40:41.975 -> Snr: 9.25
19:40:41.975 ->
Now that I’m confident my hardware is all working as expected the next step will be building a client which has a receive and transmit interrupt handler.
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