unexpected reset after changing the GPIO mode on Fly.

[RHeza.1]

Dear experts,

my STM32F042G6 is unexpectedly reset after I switched on fly CAN_TX GPIO to output GPIO pin.  

for this I did this steps.

1).HAL_CAN_STOP() and then 

 2). GPIOA->MODER &= ~((U32) "pinX");

   GPIOA->MODER|= ~(U32) "pinX");

I have also made the following steps.

1) . HAL_CAN_DeInit(hcan)

2) . HAL_GPIO_Init(x_GPIO_Port, &GPIO_InitStruct);

the result is the same. 

I have looked at the reset register (RCC->CSR). I can't find any difference to normal power on . 

after Reading (RCC->CSR) i become this Value : 0x0c80 0000

that mean : 

1) Bit 27 PORRSTF: POR/PDR reset flag

2) Bit 26 PINRSTF: PIN reset flag

3) Bit 23 V18PWRRSTF: Reset flag of the 1.8 V domain.

also set a little breakpoint before changing GPIO mode and go through the lines Step over then there will be no reset. 

but if I am in debug mode without breakpoint but through GPIO change debugging tool breaks.  

maybe somebody has an idea why this reset happens or how I can find out what he is causing the reset. 

thank you

[waclawek.jan]

GPIOA->MODER &= ~((U32) "pinX");

GPIOA->MODER|= ~(U32) "pinX");

I don't know what this means, give exactly the code you've used.

Haven't you changed a different pin than you've intended?

Observe VDD using oscilloscope. If there's a dip below 1.8V or whatever level is set to BOR, the problem is that setting that pin causes a surge in power consumption and you should check your hardware connections.

JW

[RHeza.1]

@Community member​  thank you for Answer.

the Problem was some thing else in Electronic Design that I have overshadowed.