SX1278's DIO0 pin is never being set on high, so my interrupt doesn't work

Other Hardware Sensors
1

Hello! I'm trying to read data from an SX1278 (specifically it's an Ai-Thinker Ra-02), and if I just try a LoRa.parsePacket() on the loop(), it receives everything correctly (I'm transmitting data about once every 10 seconds). However, when I try to attach an interrupt, I stop getting any information.
I use an ESP8266
Here is my code (simplified):

#include <LoRa.h>

#define LORA_CS    15 // D8
#define LORA_RST   4  // D2
#define LORA_DIO0  5  // D1

volatile bool _packetReceived = false;
volatile int _packetSize = 0;

ICACHE_RAM_ATTR void onPacketReceived(int packSize) {
  _packetReceived = true;
  _packetSize = packSize;
}

void readPackets();

void setup() {
  Serial.begin(115200);
  while (!Serial);

  delay(3000);
  LoRa.setPins(LORA_CS, LORA_RST, LORA_DIO0);

  bool ok = LoRa.begin(433E6);
  Serial.print("Result = ");
  Serial.println(ok);
  if (!ok) {
    while (1) {
      Serial.println("LoRa.begin() FAILED");
      delay(2000);
    }
  }

  LoRa.setSpreadingFactor(10);
  LoRa.setSignalBandwidth(62.5E3);
  LoRa.setCodingRate4(6);

  // I've tried both a manual interrupt and using LoRa.onReceive
  // pinMode(LORA_DIO0, INPUT);
  // attachInterrupt(digitalPinToInterrupt(LORA_DIO0), readPackets, RISING);

  LoRa.onReceive(onPacketReceived);
  LoRa.receive();
}

void loop() {
  if (_packetReceived){
      _packetReceived = false;
      // process data with _packetSize
      Serial.print("Interrupt fired");
  }

  return;
  // readPackets();  // if I skip return and readPackets() continuosly, I get all the data correctly
}

constexpr size_t payloadSize = 10;

void readPackets() {
  int packetSize = LoRa.parsePacket(payloadSize);
  if (packetSize == 0) return;

  // process data
}

If I touch the SX1278's DIO0 pin with a 3v3 wire, the interrupt fires, so I don't think there is something wrong with the code or with the cable connection. It's just not firing when RxDone. I've also switched to RadioLib (the code I shared uses Lora by sandeep mistry) but the problem remains.
If I try measuring with a multimeter, I never see that the tension goes up (although I guess that would happen too quickly for me to even notice).

What is it that I'm doing wrong? I've tried reading about the registers it uses internally but it's currently a bit too advanced for me to try to tinker with.

I'd appreciate any help you may have, thank you!

2

Have you tries the 'LoRaReceiverCallback' example provided with the library ?

I dont have ESP8266 support in my IDE to check if the standard example compiles.

By default the LoRa.h library does not use the physical DIO0 pin to check for TX or RX complete, instead the library reads the appropriate register on the SX127X which is REG_IRQFLAGS, 0x12.

3

running your program of post 1 on an ESP8266 with RA-02 receiving packets from a ESP32 with RA-02

in your program commented out (to match the defaults of the ESP32)

  //LoRa.setSpreadingFactor(10);
  //LoRa.setSignalBandwidth(62.5E3);
  //LoRa.setCodingRate4(6);

it then receives packets and displays on serial monitor

Result = 1
Interrupt firedInterrupt firedInterrupt firedInterrupt fired

check your wiring ? in particular

#define LORA_DIO0  5  // D1
4

Thanks everyone for your answers, I just found out what was happening. The transmitter sends using implicit mode (that's why in this receiver I had LoRa.parsePacket(payloadSize)). It turns out I also needed to specifiy the size on LoRa.receive(); -> LoRa.receive(payloadSize);, otherwise it couldn't parse the packet so that's why it never raised the flag on having received something!