@dc42 I see... I was trying to use the default baud rate of the device I communicate with, which is 57600. I tested with 9600 and it seems much better!
Thank you very much! I would never have thought of such a thing...

@dc42 Indeed, this is done in Platform::InitialiseInterupts like that:

...
#elif SAMC21
		NVIC_SetPriority(StepTcIRQn, NvicPriorityStep);
		NVIC_SetPriority(CAN0_IRQn, NvicPriorityCan);
# if NUM_SERIAL_PORTS >= 1
		NVIC_SetPriority(Serial0_IRQn, NvicPriorityUart);
# endif
...

And I've defined Serial0_IRQn as SERCOM2_IRQn.

Hi,

I'm trying to implement a serial communication on the TOOL1LC firmware (v3.5.3) using pins PA09 and PA12 (io0.in/out). So far, I managed to transmit what I want from the board, but I can't receive proper data and I don't understand why.

Regarding the ports configuration and serial initialization this is what I've done:

void SerialPortInit(AsyncSerial*) noexcept
{
    SetPinFunction(PortAPin(9), GpioPinFunction::D); // Rx on PA09, sercom 2, pad 1
    SetPinFunction(PortAPin(12), GpioPinFunction::C); // Tx on PA12, sercom 2, pad 0
}

void SerialPortDeinit(AsyncSerial*) noexcept
{
    pinMode(PortAPin(9), PinMode::PIN_MODE_NOT_CONFIGURED);
    pinMode(PortAPin(12), PinMode::PIN_MODE_NOT_CONFIGURED);
}

AsyncSerial uart0(2, 1, 128, 128, SerialPortInit, SerialPortDeinit);

extern "C" void SERCOM2_Handler()
{
    uart0.Interrupt();
}

Then, uart0 is used in a handler to send and read data periodically (it is spinning in the heating task, so every 250ms).

Sending data works perfectly with method uart0.write(..), but when data is uart0.available() I get only 0s (null) when I uart0.read().

I know uart is officially not supported on expansion boards, but this is the only option I have to communicate with the device I want to use. And I don't have the knowledge to build a completely new expansion board using a SammyC21, in terms of electronics.

Any help or hint would be greatly appreciated.
Thanks

@dc42 I enabled the pullup resistor for the io0.out pin, (and I found out a bad crimping contact for the X endstop... ^^').
Everthing works fine now. Thank you David.

Hi,
I'm using a Duet3 6HC, firmware 3.5.2, and I'd like to use both io0.in and io0.out for X and Y endstops but I can't make it work. I've NC microswitches wired between GND and io0.in/io0_out and my config is the following:

M574 X2 S1 P"io0.in"
M574 Y2 S1 P"io0.out"
M574 Z2 S1 P"io1.in"

For some reason, both inputs are constantly "triggered" (axes name with green background in DWC).
I thought it could be related to the fact that io0 is shared with UART (despite not using it), so I tried on the io1 header but got the same result.

Am I missing something? Should I wire the switches differently? Use invertion / pull-up (! ^) ?
Any help would be appreciated. Thank you!