Reusing Lora code

[codebrane]

This is really just a request for clarification on reusing the lora code. Trying to get an MCU using the Arduino LoRa library to work with a pico using this project.

I have an ESP32 Lolin32 Lite listening for messages from a pico which is transmitting. Both are using SX1278 modules. Both modules work as the Lolin32 can recieve from a Node MCU ESP8266 which was using the board the pico is now using. I put it back on the 8266 to verify it is working.

For the pico I've only reused from pico-tracker:

int main() {
  setup_lora(433.0, 6, "CODEBRANE");
}

unsigned char loraBuffer[20] = "Hello From Pico!";
while (1) {
  SendLoRaPacket(loraBuffer, 16, 0);
  sleep_ms(5000);
}

I modified SetupRFM98() to add:

else if (Mode == 6)
{
  ImplicitOrExplicit = IMPLICIT_MODE;
  ErrorCoding = ERROR_CODING_4_5;
  Bandwidth = BANDWIDTH_20K8;
  SpreadingFactor = SPREADING_6;
  LowDataRateOptimize = 0;
}

and the Lolin32 is using the LoRa Arduino library:

void setup() {
  if (!LoRa.begin(433E6)) {
    Serial.println("Starting LoRa failed!");
    while (1);
  }

  LoRa.setTxPower(17);
  LoRa.setSpreadingFactor(6);
  LoRa.setCodingRate4(5);
  LoRa.setSignalBandwidth(20.8E3);
}

void loop() {
  int packetSize = LoRa.parsePacket();
  if (packetSize) {
    // parse the packet
  }
}

but the receiver never picks anything up from the pico.

Is there something else I should do to reuse the lora code?

many thanks for any advice you could give.

[daveake]

So, for it to work you need 3 things:

1 - Matching frequency, remembering that LoRa modules can be a few kHz off nominal and that Tx and Rx need to be within about 20% of the set bandwidth, which is 4kHz for those settings 2 - Identical spreading factor etc 3 - For implicit mode, which you are using, Tx and Rx need to be set for the same packet length

For testing, I'd switch to explicit mode and I'd use a wider bandwidth. Remember that in doing so you may (depending on local radio laws) be breaking duty cycle and/or bandwidth limits, but for testing that's what I'd do.

Dave

On Mon, 26 Apr 2021 at 19:36, Alistair Young @.***> wrote:

This is really just a request for clarification on reusing the lora code. Trying to get an MCU using the Arduino LoRa library to work with a pico using this project.

I have an ESP32 Lolin32 Lite listening for messages from a pico which is transmitting. Both are using SX1278 modules. Both modules work as the Lolin32 can recieve from a Node MCU ESP8266 which was using the board the pico is now using. I put it back on the 8266 to verify it is working.

For the pico I've only reused from pico-tracker:

int main() { setup_lora(433.0, 6, "CODEBRANE"); }

unsigned char loraBuffer[20] = "Hello From Pico!"; while (1) { SendLoRaPacket(loraBuffer, 16, 0); sleep_ms(5000); }

I modified SetupRFM98() to add:

else if (Mode == 6) { ImplicitOrExplicit = IMPLICIT_MODE; ErrorCoding = ERROR_CODING_4_5; Bandwidth = BANDWIDTH_20K8; SpreadingFactor = SPREADING_6; LowDataRateOptimize = 0; }

and the Lolin32 is using the LoRa Arduino library:

void setup() { if (!LoRa.begin(433E6)) { Serial.println("Starting LoRa failed!"); while (1); }

LoRa.setTxPower(17); LoRa.setSpreadingFactor(6); LoRa.setCodingRate4(5); LoRa.setSignalBandwidth(20.8E3); }

void loop() { int packetSize = LoRa.parsePacket(); if (packetSize) { // parse the packet } }

but the receiver never picks anything up from the pico.

Is there something else I should do to reuse the lora code?

many thanks for any advice you could give.

— You are receiving this because you are subscribed to this thread. Reply to this email directly, view it on GitHub https://github.com/daveake/pico-tracker/issues/3, or unsubscribe https://github.com/notifications/unsubscribe-auth/AAIGQ5FZKVKHB3GTQ4ATLTDTKWXDBANCNFSM43TNVCBA .

[codebrane]

thank you very much for your advice, it's very much appreciated.

Based on what you said about testing I got them communicating with the following on the pico:

int main() {
  setup_lora(433, 6, "CODEBRANE");
  unsigned char loraBuffer[20] = "Hello From Pico!";
  while (1) {
    SendLoRaPacket(loraBuffer, 16, 0);
    sleep_ms(5000);
  }
}

void SetupRFM98(float Frequency, int Mode) {
  else if (Mode == 6)
  {
    ImplicitOrExplicit = EXPLICIT_MODE;
    ErrorCoding = ERROR_CODING_4_8;
    Bandwidth = BANDWIDTH_62K5;
    SpreadingFactor = SPREADING_8;
    LowDataRateOptimize = 0;
  }
}

and on the ESP32:

void setup() {
  if (!LoRa.begin(433E6)) {
    Serial.println("Starting LoRa failed!");
    while (1);
  }

  LoRa.setTxPower(17);
  LoRa.setSpreadingFactor(8);
  LoRa.setCodingRate4(8);
  LoRa.setSignalBandwidth(62.5E3);
}

[daveake]

Excellent. If you can get the received frequency error from the receiver code, then you adjust either the receiver or transmitter to make that about zero, then you can use a narrower bandwidth.

On Mon, 26 Apr 2021, 20:13 Alistair Young, @.***> wrote:

thank you very much for your advice, it's very much appreciated.

Based on what you said about testing I got them communicating with the following on the pico:

int main() { setup_lora(433, 6, "CODEBRANE"); unsigned char loraBuffer[20] = "Hello From Pico!"; while (1) { SendLoRaPacket(loraBuffer, 16, 0); sleep_ms(5000); } }

void SetupRFM98(float Frequency, int Mode) { else if (Mode == 6) { ImplicitOrExplicit = EXPLICIT_MODE; ErrorCoding = ERROR_CODING_4_8; Bandwidth = BANDWIDTH_62K5; SpreadingFactor = SPREADING_8; LowDataRateOptimize = 0; } }

and on the ESP32:

void setup() { if (!LoRa.begin(433E6)) { Serial.println("Starting LoRa failed!"); while (1); }

LoRa.setTxPower(17); LoRa.setSpreadingFactor(8); LoRa.setCodingRate4(8); LoRa.setSignalBandwidth(62.5E3); }

— You are receiving this because you commented. Reply to this email directly, view it on GitHub https://github.com/daveake/pico-tracker/issues/3#issuecomment-827080432, or unsubscribe https://github.com/notifications/unsubscribe-auth/AAIGQ5ES47PH2NCMFCEII5DTKW3OZANCNFSM43TNVCBA .

[codebrane]

I'll close the issue now, thanks for the help. Got it down to 15Kz. I think to get it lower I'll need a TCXO.