Lora sx1278 does not initialize with arduino r4 minima

Projects General Guidance
1

Hello, I can't initialize my lora sx1278 with my arduino r4. I would like to know if my wiring is correct. I'm using level converters and a 3v3 power supply for the lora.

Here's the schematic.

7ffa8fecbd5a4afd1de1fdabab7b45b10c9dca0a
7ffa8fecbd5a4afd1de1fdabab7b45b10c9dca0a1487×827 111 KB

The program I use

#include <SPI.h>
#include <LoRa.h>

void setup() {
  Serial.begin(9600);
  while (!Serial);

  Serial.println("LoRa Receiver");

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

void loop() {}

Here are the references of my components

If you have any ideas on how to solve my problem, that would be very helpful

2

Are you absolutely sure all the I/O pin assignments indicated by the posted wiring diagram are consistent with the assumptions made by the radio library for the Arduino Uno R4? Pin assignments for the SPI bus are somewhat standardized, but those for RST and interrupt pins vary between MCU boards.

It is usually best to state the pin assignments explicitly, in the code.

3

I based myself on this table and the R4 datasheet confirms it.

Table of pin

Datasheet UNO R4
Datasheet UNO R4744×770 79.3 KB

But you should know that a few months ago, I was using LoRa directly via the R4's 3V3 and without a level converter for the SPI.

This worked, but I was advised to use an external power supply for the 3.3V, as the Ra-02 current is higher (93mA) than the board's 3.3V regulator can supply 50mA.

And I'm using level converters for the first time, because I noticed that my voltage at the Ra-02 was higher than 3.3V.

So, theoretically, I can eliminate the program and the SPI R4 pins from my LoRa initialization problem.

I'll just have to see whether my level converter wiring is correct or not.

4

That may have damaged the radio module, and I'm surprised that it seemed to work.

It is easy to test the level converter, using a multimeter to check output voltages.

5

Ok, I tried again without the level converters. I connected the SPI bus directly to the R4 pins. I have a voltage of 3.33v at the LoRa pins. It initializes correctly and I'm also receiving packets from my transmitters. So my LoRa is not damaged.

I confess I don't understand.

6

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