NRF24L01 Troubleshooting Guide for M5 Core2 Users
Thanks for bringing this up! The “NRF24 not detected” message usually points to a wiring, power, or SPI initialization issue. While detailed documentation for NRF24L01 specifically paired with M5 Core2 is limited, here’s a comprehensive set of checks to help you isolate the problem.
Verify SPI Wiring
The NRF24L01 relies on proper SPI mapping. Make sure the following pins align with the Core2’s hardware SPI bus:
MOSI → GPIO 23
MISO → GPIO 38
SCK → GPIO 18
CSN (CS) → GPIO 5 or GPIO 26
CE → Any free GPIO (commonly GPIO 4 or 5 depending on your setup)
VCC → 3.3V (never 5V)
GND → Ground
⚠ Tip: Loose CSN or CE wiring is one of the most common causes of NRF24 initialization failure.
Power Stability Check
The NRF24L01 is notoriously sensitive to voltage noise.
Ensure a clean 3.3V feed (not exceeding 3.6V).
Add a 0.1µF ceramic capacitor close to the module’s VCC/GND pins.
Prefer a separate 3.3V regulator if you are using the PA+LNA high-powered version.
The module may draw up to ~100mA during TX, so confirm your supply can deliver this reliably.
Library & Firmware Setup
Make sure the correct software environment is in place:
Install TMRh20’s RF24 library via Arduino IDE → Library Manager.
Update your M5Core2 library from GitHub.
Use a fresh example sketch from the RF24 library to confirm base connectivity.
Example Initialization Code
Adjust pins depending on your wiring:
#include <SPI.h>
#include <RF24.h>
RF24 radio(4, 5); // CE pin, CSN pin
void setup() {
Serial.begin(115200);
if (!radio.begin()) {
Serial.println("NRF24 module NOT detected!");
return;
}
Serial.println("NRF24 module initialized.");
radio.setPALevel(RF24_PA_MIN);
radio.setDataRate(RF24_250KBPS);
radio.openReadingPipe(0, 0xAABBCCDDEEULL);
radio.startListening();
}
void loop() {}
If this fails, the wiring or hardware is almost certainly the issue.
Hardware Integrity Checks
Before assuming software issues, confirm physical reliability:
Inspect solder joints and header pins.
Use a multimeter to confirm continuity on MOSI/MISO/SCK/CSN/CE lines.
Try a second NRF24 module if available, these modules can fail easily.
Swap CSN/CE to alternate GPIOs if conflicts exist.
