To anyone trying something similar in the future
MODULE_4IN8OUT module; MFRC522_I2C mfrc522(0x28, -1, &Wire); void setup() { M5.begin(true, true, true, true); Serial.begin(115200); delay(500); Serial.println("Starting setup..."); M5.Lcd.println("Init..."); // POWER MANAGEMENT dla Port A (RFID) M5.Axp.SetBusPowerMode(0); M5.Axp.SetLDOEnable(2, true); delay(200); // --- I2C BUSES --- Wire.begin(32, 33, 100000); Wire1.begin(21, 22, 100000); delay(100); M5.Lcd.println("Init 4IN8OUT..."); // Start module 4IN8OUT if (!module.begin(&Wire1, 21, 22, MODULE_4IN8OUT_ADDR)) { M5.Lcd.setTextColor(RED); M5.Lcd.println("4IN8OUT INIT FAIL"); Serial.println("4IN8OUT INIT FAIL"); while (1) delay(1000); } M5.Lcd.setTextColor(GREEN); M5.Lcd.println("4IN8OUT OK!"); Serial.println("4IN8OUT OK!"); M5.Lcd.setTextColor(WHITE); // Init RFID mfrc522.PCD_Init(); M5.Lcd.println("RFID OK!"); Serial.println("RFID OK!");