MCP2515 in Interrupt mode using STM32WL

[FPicc.1]

Hi all,

I'm using MCP2515 for a CAN application in the NUCLEO STM32WL board. I've managed to get it to work in pulling mode, however, I want to use interrupt mode. 

For what I looked, I just have to enable the MCP interrupt pin in EXTI mode in cubeMX, but the MCP interrupt pin that I set (PA0) is already set as the BUT1 pin (on board button). I didn't change the configurations, only set in the callback to activate if occurs the rising edge of BUT1_Pin (tried with falling edge too).

It didn't work, but I don't know if I have to configure something more, or the fact that the pin is shared with the button changes something and it could be the problem.

Any insights will be helpfull.

[Tesla DeLorean]

And how is the Button wired? Pull-up to VCC, button pressed to GND ?

Not sure the MCP2515 uses an open-collector output, or can be configured from a driver, level or pulse sense. Sure the Data Sheet would elucidate.

Use EXTI0

Use a scope and confirm behaviour and expectations

[FPicc.1]

Here's the schematic of BUT1 pin. I'm not sure if the PA0 bypasses this connection, or if would only work if the button is pressed

[Tesla DeLorean]

Ok, so NUCLEO-WL55JC(1) board

You could remove the solder-bridge (SB16) or link, or move to PC13 (SB15) if nothing else conflicts, and use the EXTI15_9

That would free PA0 for your own, personal use, on the MORPHO connection/headers

[FPicc.1]

Ok, so if I just remove the SB16 solder, the PA0 pin would be available to use on the MORPHO connectors, or simply just use the PC13 pin, right?

[FPicc.1]

Hey, just updating.

I changed, the pin I was using for the interrupt. It is connected directly to the interrupt MCP2515 IC pin. I pu the osciloscope on the pin, and couldn't see nothing, only a voltage offset.

What could it be? I need to do something else?

[Techn]

Have you programmed the mcp registers to generate interrupt.  If you post the code we can analyse

[FPicc.1]

I don't think so, at least not in the main code. The callback code follows:

void HAL_GPIO_EXTI_Callback(uint16_t GPIO_Pin)
{
    if (GPIO_Pin == CAN_INT_Pin) //MCP2515 Interrupt Pin
    {
	  //CAN receiving messages (Packages MUST start from the smaller data)
	  if(CANSPI_Receive(&rxMessage))
	  {

		  switch(rxMessage.frame.id)
		  {

		  //------------ BMS packages ------------ (2 bytes variables must be inverted)
		  case 0x672:
			  bms_fail = (rxMessage.frame.data4);
			  break;

		  case 0x673:
			  accumulator_voltage  = ((rxMessage.frame.data0 << 8) | rxMessage.frame.data1);
			  min_cell_voltage 	   = (rxMessage.frame.data2);
			  max_cell_voltage 	   = (rxMessage.frame.data4);
			  break;
...
...
...
      }
}

To make it work I'm using this library: https://github.com/eziya/STM32_SPI_MCP2515.git

(MCP2515 and CANSPI files)

I don't know if this does program the registers to generate the interrupt or has a function of some kind to do it.

[Techn]

Ad per datasheet the int pin can be configured for different purposes.  Are you using any breakout,  then check the jumpers.  I  guess it needs pullups 

[FPicc.1]

Also don't know, here's the schematic on the board (consider PA0 as PB14 (CAN_INT_Pin))