Hi, In GRAY M5STACK unfortunatelly PortA is used for I2C to some internal chip. Sometime GPS not work on Grove Cable.

Just connect GPS to
16RX <<< TX White
17TX >>> Rx Yellow
And all start working with no problem.

Example code from Arduino works if You add

#define RX1 16
#define TX1 17
...
void setup()
{
M5.begin();
M5.Power.begin();
GPSRaw.begin(9600, SERIAL_8N1,RX1,TX1);

Hi, In GRAY M5STACK unfortunatelly PortA is used for I2C to some internal chip. Sometime GPS not work on Grove Cable.

Just connect GPS to
16RX <<< TX White
17TX >>> Rx Yellow
And all start working with no problem.

Example code from Arduino works if You add

#define RX1 16
#define TX1 17
...
void setup()
{
M5.begin();
M5.Power.begin();
GPSRaw.begin(9600, SERIAL_8N1,RX1,TX1);