Portenta H7 - Serial1 not working


Portenta H7 with Lora Shield connected over the high density connectors.
On the header connector I use I2C and SPI to drive a TFT Display. This works perfectly.

I tried without success to use the serial port on the H7 header connector for a GPS Breakout.
D14 / PA9 UART1_TX
D13 / PA10 UART1_RX

Serial1.begin(9600); is executed, but I don't get data from my serial device.
Yes, TX->RX and RX->TX is done. GND connected

Is there a trick?
Is Serial1 not the right name?
Is it used anywhere else?

Thanks for a tip.


Can somebody confirm, that the serial1 Port ist working from the M7 core at the header pins D13/D14 if the lora-shield is connected?

Must i do something with the extra pins RTS/CTS, only available on the high density port?

I still don't get serial1 running, to receive data from a GPS modul.

I am not sure, but my impression after digging in mbed API code:
serial1 seems to use the same UART on CM4 side as CM7 (as serial). I guess (!), serial1 is for CM4 only and using the same UART as CM7.
It might not be a different UART, with different pins.

Hi @wapel,
Did you manage to figure out a way to run the GPS module on the Portenta?

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