SX1262 Initialization Error -2

[joshuasv]

I am trying to run an example script but get error -2.

This is my code:

/*
  RadioLib SX126x FSK Modem Example

  This example shows how to use FSK modem in SX126x chips.

  NOTE: The sketch below is just a guide on how to use
        FSK modem, so this code should not be run directly!
        Instead, modify the other examples to use FSK
        modem and use the appropriate configuration
        methods.

  For default module settings, see the wiki page
  https://github.com/jgromes/RadioLib/wiki/Default-configuration#sx126x---fsk-modem

  For full API reference, see the GitHub Pages
  https://jgromes.github.io/RadioLib/
*/

// include the library
#include <RadioLib.h>

// SX1262 has the following connections:
// NSS pin:   4
// DIO1 pin:  5
// NRST pin:  6
// BUSY pin:  7
SX1262 radio = new Module(4, 5, 6, 7);

// or detect the pinout automatically using RadioBoards
// https://github.com/radiolib-org/RadioBoards
/*
#define RADIO_BOARD_AUTO
#include <RadioBoards.h>
Radio radio = new RadioModule();
*/

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

  while (!Serial)
  {
    delay(50);
  }

  // initialize SX1262 FSK modem with default settings
  Serial.print(F("[SX1262] Initializing ... "));

  // void SPIClass::begin(int8_t sck, int8_t miso, int8_t mosi, int8_t ss)
  SPI.begin(13, 14, 12, 4);

  int state = radio.beginFSK();
  if (state == RADIOLIB_ERR_NONE) {
    Serial.println(F("success!"));
  } else {
    Serial.print(F("failed, code "));
    Serial.println(state);
    while (true) { delay(10); }
  }

  // if needed, you can switch between LoRa and FSK modes
  //
  // radio.begin()       start LoRa mode (and disable FSK)
  // radio.beginFSK()    start FSK mode (and disable LoRa)

  // the following settings can also
  // be modified at run-time
  state = radio.setFrequency(433.5);
  state = radio.setBitRate(100.0);
  state = radio.setFrequencyDeviation(10.0);
  state = radio.setRxBandwidth(250.0);
  state = radio.setOutputPower(10.0);
  state = radio.setCurrentLimit(100.0);
  state = radio.setDataShaping(RADIOLIB_SHAPING_1_0);
  uint8_t syncWord[] = {0x01, 0x23, 0x45, 0x67,
                        0x89, 0xAB, 0xCD, 0xEF};
  state = radio.setSyncWord(syncWord, 8);
  if (state != RADIOLIB_ERR_NONE) {
    Serial.print(F("Unable to set configuration, code "));
    Serial.println(state);
    while (true) { delay(10); }
  }

  // FSK modem on SX126x can handle the sync word setting in bits, not just
  // whole bytes. The value used is left-justified.
  // This makes same result as radio.setSyncWord(syncWord, 8):
  state = radio.setSyncBits(syncWord, 64);
  // This will use 0x012 as sync word (12 bits only):
  state = radio.setSyncBits(syncWord, 12);

  // FSK modem allows advanced CRC configuration
  // Default is CCIT CRC16 (2 bytes, initial 0x1D0F, polynomial 0x1021, inverted)
  // Set CRC to IBM CRC (2 bytes, initial 0xFFFF, polynomial 0x8005, non-inverted)
  state = radio.setCRC(2, 0xFFFF, 0x8005, false);
  // set CRC length to 0 to disable CRC

  #warning "This sketch is just an API guide! Read the note at line 6."
}

void loop() {
  // FSK modem can use the same transmit/receive methods
  // as the LoRa modem, even their interrupt-driven versions

  // transmit FSK packet
  int state = radio.transmit("Hello World!");
  /*
    byte byteArr[] = {0x01, 0x23, 0x45, 0x67,
                      0x89, 0xAB, 0xCD, 0xEF};
    int state = radio.transmit(byteArr, 8);
  */
  if (state == RADIOLIB_ERR_NONE) {
    Serial.println(F("[SX1262] Packet transmitted successfully!"));
  } else if (state == RADIOLIB_ERR_PACKET_TOO_LONG) {
    Serial.println(F("[SX1262] Packet too long!"));
  } else if (state == RADIOLIB_ERR_TX_TIMEOUT) {
    Serial.println(F("[SX1262] Timed out while transmitting!"));
  } else {
    Serial.println(F("[SX1262] Failed to transmit packet, code "));
    Serial.println(state);
  }

  // receive FSK packet
  String str;
  state = radio.receive(str);
  /*
    byte byteArr[8];
    int state = radio.receive(byteArr, 8);
  */
  if (state == RADIOLIB_ERR_NONE) {
    Serial.println(F("[SX1262] Received packet!"));
    Serial.print(F("[SX1262] Data:\t"));
    Serial.println(str);
  } else if (state == RADIOLIB_ERR_RX_TIMEOUT) {
    Serial.println(F("[SX1262] Timed out while waiting for packet!"));
  } else {
    Serial.println(F("[SX1262] Failed to receive packet, code "));
    Serial.println(state);
  }
}

This what comes out of serial:

[SX1262] Initializing ... [1.115685] RLB_DBG: 
RadioLib Info
             Version:  "7.2.0.0"
Platform: "ESP32"
"Jun 23 2025" "20:57:59"
[2.119567] RLB_DBG: SX126x not found! (1 of 10 tries) RADIOLIB_SX126X_REG_VERSION_STRING:
[2.119845] RLB_DBG: 00000320: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff  ................
[2.119952] RLB_DBG: Expected string: SX1261
[3.133557] RLB_DBG: SX126x not found! (2 of 10 tries) RADIOLIB_SX126X_REG_VERSION_STRING:
[3.133780] RLB_DBG: 00000320: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff  ................
[3.133880] RLB_DBG: Expected string: SX1261
[4.147559] RLB_DBG: SX126x not found! (3 of 10 tries) RADIOLIB_SX126X_REG_VERSION_STRING:
[4.147779] RLB_DBG: 00000320: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff  ................
[4.147879] RLB_DBG: Expected string: SX1261
[5.161557] RLB_DBG: SX126x not found! (4 of 10 tries) RADIOLIB_SX126X_REG_VERSION_STRING:
[5.161781] RLB_DBG: 00000320: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff  ................
[5.161878] RLB_DBG: Expected string: SX1261
[6.175559] RLB_DBG: SX126x not found! (5 of 10 tries) RADIOLIB_SX126X_REG_VERSION_STRING:
[6.175782] RLB_DBG: 00000320: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff  ................
[6.175879] RLB_DBG: Expected string: SX1261
[7.189557] RLB_DBG: SX126x not found! (6 of 10 tries) RADIOLIB_SX126X_REG_VERSION_STRING:
[7.189777] RLB_DBG: 00000320: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff  ................
[7.189887] RLB_DBG: Expected string: SX1261
[8.203559] RLB_DBG: SX126x not found! (7 of 10 tries) RADIOLIB_SX126X_REG_VERSION_STRING:
[8.203777] RLB_DBG: 00000320: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff  ................
[8.203881] RLB_DBG: Expected string: SX1261
[9.217557] RLB_DBG: SX126x not found! (8 of 10 tries) RADIOLIB_SX126X_REG_VERSION_STRING:
[9.217777] RLB_DBG: 00000320: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff  ................
[9.217886] RLB_DBG: Expected string: SX1261
[10.231559] RLB_DBG: SX126x not found! (9 of 10 tries) RADIOLIB_SX126X_REG_VERSION_STRING:
[10.231781] RLB_DBG: 00000320: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff  ................
[10.231893] RLB_DBG: Expected string: SX1261
[11.245557] RLB_DBG: SX126x not found! (10 of 10 tries) RADIOLIB_SX126X_REG_VERSION_STRING:
[11.245790] RLB_DBG: 00000320: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff  ................
[11.245895] RLB_DBG: Expected string: SX1261
[11.256329] RLB_DBG: No SX126x found!
failed, code -2

How can I fix it?

[jgromes]

How can I fix it?

Mostly by following the (IMO) quite extensive docs here - we have a Wiki, which even incldues a dedicated Troubleshooting page. We have a complete documentation of all public API methods, including all status codes.

At this point I fell like we have done everything we can to point people to the places they can find answers. I genuinely do not know where else to put the information anymore. It's all in the readme, it's all in the examples ... you only have to click on the links.

[HeadBoffin]

Leaving aside the docs, this is like phoning your car breakdown service and saying "My car won't start" and hanging up - we've no clue what MCU board you are using - if it's a known one, you should be able to find the pin settings, if it has a schematic, you should be able to find the pin settings, if you made the board, you should know the pin settings ...