Particle with LoRa & Sleep mode

Troubleshooting
1

Hey Everyone!

I’m looking for some advice for a project I’m working on.

I have an Electron connected to a LoRa module. (sx1276) operating as a Callback receiver.

The Electron waits for a signal from DIO0 on the LoRa which is connected to D2 on the Electron to begin the data RX.

The issue I am having is that I also want the Electron to wait on this signal to wake up from sleep mode. ie. System.sleep(D2, RISING);

The issue I am having is that when D2 goes high, the Electron wakes up but I’m not getting the data from the LoRa module. I think the reason is that both System.sleep and the SPI code for LoRa are looking for the rising edge however only the System.sleep part is able to see it.

Thanks.

2

I’m not sure I understand exactly what you’re doing but I have the RFM95w LoRa radios working with the Photon.

Can you add a delay between waking up the Electron and starting the process of receiving the LoRa TX info on the Electron RX line?

3

Hey!

I do have the LoRa working,I am running into issues because I am trying to reduce the power consumption.

I am trying to sleep the Particle until there is data incoming. The way i am trying to do this is to listen for the preamble on D2.

The problem is that when I put in the function System.sleep(D2, RISING); The preamble signal on D2 from the LoRa stops being generated.

Thanks,

4

@PeaTearDial, which LoRa module are you using exactly?

5

Hey im using a DRF1276G.

6

@PeaTearDial, which DIO pin on the module are you using for the PreAmble detect?

7

Hey, I’m using DIO0.

8

I believe when RISING is selected, the INPUT_PULLDOWN pinMode is selected, which the LoRa module might not like ( which is surprising). Setting the interrupt to CHANGE will leave the pin floating (like a typical input). I believe the LoRa module is already driving the DIO0 pin LOW anyway so a pull-down is not necessary. The interrupt will fire on the first change on DIO0 so it should work.

9

Hey, thanks for the info. Unfortunately it didn’t work. if I leave out the sleep command I can see the change on DIO0 with the my scope. When I put in the sleep command, the signal disappears.

    SYSTEM_MODE(SEMI_AUTOMATIC);
// This #include statement was automatically added by the Particle IDE.
#include "LoRa.h"

#include <SPI.h>
char temp[40];

void setup() {
  //LoRa.setSPIFrequency(4e6);
  delay(5000); //take a break
  Serial.begin(9600);
  

  delay(1000); //take a break

  Serial.println("LoRa Receiver");

  if (!LoRa.begin(915E6)) {
    Serial.println("Starting LoRa failed!");
    while (1);
  }
 
}

void loop() {
    
    System.sleep(D2, CHANGE);
    
    // try to parse packet
  int packetSize = LoRa.parsePacket();
  if (packetSize) {
    // received a packet
    Serial.print("Received packet '");

    // read packet
    int i = 0;
     
    while (LoRa.available()) {
      char spi = ((char)LoRa.read()); 
      
      temp[i] = spi;
      Serial.print(temp[i]);
      i++;
    }
    
    // print RSSI of packet
    Serial.print("' with RSSI ");
    Serial.println(LoRa.packetRssi());
    
    
    
    char buffer[3];
    buffer[0] = temp[15];
    buffer[1] = temp[16];
    buffer[3] = '\0';

    int  n;
    n = atoi(buffer);
    Serial.println(n);

    


  }
  
}
10

@PeaTearDial, comment out the sleep and at the end of setup() add pinMode(D2, INPUT); and see if the DIO0 signal remains.

11

Hey, yes the DIO0 signal is still there…

12

What other pins/power do you have connected between the Electron and the LoRa module?

13

Hey, I am connected to the following pins.

SCK – A3
MISO – A4
MOSI – A5
NSS – A2
RST – D0
3.3V – 3V3
GND – GND

14

Instead
// try to parse packet
int packetSize = LoRa.parsePacket();
I have used directly
// try to check available
int packetSize = LoRa.available();
And then it works.

But an important thing that I have used for my LoRa Ra-02 (433 Mhz) after
if (!LoRa.begin(433E6)) while(1);
I have added continous reading command for trigger interrupt else to me not works
if (!LoRa.begin(433E6)) while(1);
LoRa.receive();

Then I have some problems to perform this method ever, so I repeat begin and receive in loop cicle inside the code if (packetSize) { at bottom of code before the closing bracket }