Hi @osioli, You can upload to the core first this code (I'm using the Gray core): #include <M5Stack.h> HardwareSerial GPS(2); void setup() { GPS.begin(9600); Serial.begin(115200); } void loop() { for (;;) { if (GPS.available() > 0) Serial.write(GPS.read()); if (Serial.available() > 0) GPS.write(Serial.read()); } } In u-center set the baud rate to 115200. Go to View-Messages View (F9), expand UBX-CFG-MSG and check UART1. In my case the satellites detection only works outdoors.