/// <summary>
/// Get the RSSI correction constant.
/// </summary>
/// <returns></returns>
private int GetRssiCorrection()
{
// Page 87 in Semtech SX1276 datasheet.
return(RegisterManager.Read <CommonRegisterOpMode>().LowFrequencyModeOn == CommonRegisterOpMode.LowFrequencyModeOnEnum.HighFrequencyMode
? -157
: -164);
}
protected Transceiver(SpiDevice spiDevice, TransceiverSettings settings, TransceiverPinSettings pinSettings)
{
Settings = settings;
_spiCommController = new SpiCommController(spiDevice);
SpiComm = _spiCommController.Create(pinSettings.ChipSelectPinNumber);
Pins = CreatePins(pinSettings);
Pins.Dio0.ValueChanged += Dio0Pin_ValueChanged;
RegisterManager = new RegisterManager(SpiComm);
}
private void EnterReceiveMode()
{
RegisterManager.Write(new CommonRegisterOpMode(
CommonRegisterOpMode.LongRangeModeEnum.LoRaMode,
CommonRegisterOpMode.AccessSharedRegEnum.AccessLoRaRegisterPage,
CommonRegisterOpMode.LowFrequencyModeOnEnum.HighFrequencyMode,
CommonRegisterOpMode.DeviceModeEnum.ReceiveContinuous));
RegisterManager.Write(new CommonRegisterDioMapping1(
CommonRegisterDioMapping1.Dio0MappingEnum.RxDone,
CommonRegisterDioMapping1.Dio1MappingEnum.RxTimeout,
CommonRegisterDioMapping1.Dio2MappingEnum.FhssChangeChannel1,
CommonRegisterDioMapping1.Dio3MappingEnum.CadDone));
}
private void HandleTransmission(Transmission transmission)
{
try
{
lock (_registerFifoLock)
{
// Allow the full FIFO size for transmission
RegisterManager.Write(new LoraRegisterFifoTxBaseAddr(0));
// Position at the beginning of the FIFO
RegisterManager.Write(new LoraRegisterFifoAddrPtr(0));
// The message data
foreach (byte b in transmission.Buffer)
{
RegisterManager.Write(new CommonRegisterFifo(b));
}
// Write the message length
RegisterManager.Write(new LoraRegisterPayloadLength((byte)transmission.Buffer.Length));
_transmissionCompletedEventSlim.Reset();
// Start the transmitter
EnterTransmitMode();
}
try
{
// Wait for the transmission to finish.
_transmissionCompletedEventSlim.Wait(transmission.CancellationToken);
}
catch (OperationCanceledException)
{
}
// Was it cancelled?
transmission.TransmissionCompletionSource.SetResult(!transmission.CancellationToken.IsCancellationRequested);
}
catch (Exception exception)
{
transmission.TransmissionCompletionSource.SetException(exception);
}
finally
{
// Go back to receiver-mode.
EnterReceiveMode();
}
}
private void EnterTransmitMode()
{
RegisterManager.Write(new CommonRegisterOpMode(
CommonRegisterOpMode.LongRangeModeEnum.LoRaMode,
CommonRegisterOpMode.AccessSharedRegEnum.AccessLoRaRegisterPage,
CommonRegisterOpMode.LowFrequencyModeOnEnum.HighFrequencyMode,
CommonRegisterOpMode.DeviceModeEnum.Transmit));
// Interrupt on TxDone
RegisterManager.Write(new CommonRegisterDioMapping1(
CommonRegisterDioMapping1.Dio0MappingEnum.TxDone,
CommonRegisterDioMapping1.Dio1MappingEnum.RxTimeout,
CommonRegisterDioMapping1.Dio2MappingEnum.FhssChangeChannel1,
CommonRegisterDioMapping1.Dio3MappingEnum.CadDone));
}
private void Dio0Pin_ValueChanged(GpioPin sender, GpioPinValueChangedEventArgs args)
{
if (args.Edge != GpioPinEdge.RisingEdge)
{
return;
}
LoraRegisterIrqFlags.FlagsEnum irqFlags = RegisterManager.Read <LoraRegisterIrqFlags>().Flags;
if (irqFlags.HasFlag(LoraRegisterIrqFlags.FlagsEnum.TxDone))
{
TransmittedOkCount++;
_transmissionCompletedEventSlim.Set();
}
if (irqFlags.HasFlag(LoraRegisterIrqFlags.FlagsEnum.RxDone))
{
ReceivedMessage message = GetReceivedMessage();
OnMessageReceived?.Invoke(this, new ReceivedMessageEventArgs(message));
}
// Clear all IRQ flags
RegisterManager.Write(new LoraRegisterIrqFlags(0xFF));
}
private ReceivedMessage GetReceivedMessage()
{
DateTime timestamp = DateTime.UtcNow;
LoraRegisterIrqFlags.FlagsEnum irqFlags = RegisterManager.Read <LoraRegisterIrqFlags>().Flags;
bool timeout;
if (irqFlags.HasFlag(LoraRegisterIrqFlags.FlagsEnum.RxTimeout))
{
timeout = true;
ReceivedTimeoutCount++;
}
else
{
timeout = false;
}
bool crcOk;
if (irqFlags.HasFlag(LoraRegisterIrqFlags.FlagsEnum.PayloadCrcError))
{
crcOk = false;
ReceivedBadCrcCount++;
}
else
{
crcOk = true;
}
if (!timeout && crcOk)
{
ReceivedOkCount++;
}
lock (_registerFifoLock)
{
// Get the FIFO-address of the last received packet
byte currentFifoAddr = RegisterManager.Read <LoraRegisterFifoRxCurrentAddr>().Addr;
// Go to that address
RegisterManager.Write(new LoraRegisterFifoAddrPtr(currentFifoAddr));
// Get the number of received bytes
byte receivedCount = RegisterManager.Read <LoraRegisterRxNbBytes>().FifoRxBytesNb;
// Prepare a buffer to copy to from the FIFO queue
var buffer = new byte[receivedCount];
// Copy from the FIFO queue
for (int i = 0; i < receivedCount; i++)
{
buffer[i] = RegisterManager.Read <CommonRegisterFifo>().Value;
}
// Get the RSSI correction value
int rssiCorrection = GetRssiCorrection();
// Get the adjusted RSSI value
int rssi = RegisterManager.Read <LoraRegisterRssiValue>().Rssi + rssiCorrection;
// Get the adjusted RSSI value of the packet
int pktRssi = RegisterManager.Read <LoraRegisterPktRssiValue>().PacketRssi + rssiCorrection;
// Get the packet signal-to-noise ratio
float pktSnr = (float)Math.Round(RegisterManager.Read <LoraRegisterPktSnrValue>().PacketSnr / 4d, 1);
#if DEBUG
Debug.WriteLine($"Packet RSSI: {pktRssi}, RSSI: {rssi}, SNR: {pktSnr}, Length: {buffer.Length}");
#endif
return(new ReceivedMessage(buffer, rssi, pktRssi, pktSnr, crcOk, timeout, timestamp));
}
}
protected override async Task Init()
{
Pins.Reset.Write(GpioPinValue.Low);
await Task.Delay(10);
Pins.Reset.Write(GpioPinValue.High);
await Task.Delay(10);
CommonRegisterVersion version = RegisterManager.Read <CommonRegisterVersion>();
if (version.Value == 0x12)
{
Debug.WriteLine("SX1276/77/78/79 detected, starting.");
}
else
{
throw new Exception("Unrecognized transceiver.");
}
RegisterManager.Write(new CommonRegisterOpMode(
CommonRegisterOpMode.LongRangeModeEnum.LoRaMode,
CommonRegisterOpMode.AccessSharedRegEnum.AccessLoRaRegisterPage,
CommonRegisterOpMode.LowFrequencyModeOnEnum.HighFrequencyMode,
CommonRegisterOpMode.DeviceModeEnum.Sleep));
uint frf = (uint)(((ulong)Settings.Frequency << 19) / 32000000);
RegisterManager.Write(new CommonRegisterFrf(frf));
RegisterManager.Write(new LoraRegisterSyncWord(Settings.LoraSyncWord.Value));
RegisterManager.Write(new LoraRegisterModemConfig1(
ConvertBandWidth(Settings.BandWidth),
ConvertCodingRate(Settings.CodingRate),
LoraRegisterModemConfig1.HeaderModeEnum.ExplicitHeaderMode));
RegisterManager.Write(new LoraRegisterModemConfig2(
ConvertSpreadingFactor(Settings.SpreadingFactor),
LoraRegisterModemConfig2.TxModeEnum.NormalMode,
Settings.CrcEnabled ? LoraRegisterModemConfig2.RxPayloadCrcEnum.CrcEnabled : LoraRegisterModemConfig2.RxPayloadCrcEnum.CrcDisabled,
Settings.SymbolTimeout));
RegisterManager.Write(new LoraRegisterModemConfig3(
Settings.EnableLowDataRateOptimize ? LoraRegisterModemConfig3.LowDataRateOptimizeEnum.Enabled : LoraRegisterModemConfig3.LowDataRateOptimizeEnum.Disabled,
LoraRegisterModemConfig3.AgcAutoEnum.Enabled));
RegisterManager.Write(new LoraRegisterMaxPayloadLength(0x80));
RegisterManager.Write(new LoraRegisterPayloadLength(0x40));
RegisterManager.Write(new LoraRegisterHopPeriod(0xFF));
RegisterManager.Write(new LoraRegisterFifoRxBaseAddr(0x00));
RegisterManager.Write(new LoraRegisterFifoTxBaseAddr(0x80));
byte fifoRxBaseAddr = RegisterManager.Read <LoraRegisterFifoRxBaseAddr>().FifoRxBaseAddr;
RegisterManager.Write(new LoraRegisterFifoAddrPtr(fifoRxBaseAddr));
RegisterManager.Write(new CommonRegisterLna(
CommonRegisterLna.LnaGainEnum.G1Max,
CommonRegisterLna.LnaBoostLfEnum.DefaultLnaCurrent,
CommonRegisterLna.LnaBoostHfEnum.BoostOn));
RegisterManager.Write(new CommonRegisterOpMode(
CommonRegisterOpMode.LongRangeModeEnum.LoRaMode,
CommonRegisterOpMode.AccessSharedRegEnum.AccessLoRaRegisterPage,
CommonRegisterOpMode.LowFrequencyModeOnEnum.HighFrequencyMode,
CommonRegisterOpMode.DeviceModeEnum.ReceiveContinuous));
}
