STM32F0 reset problem

[gunahmt]

Hi everyone,

I use a custom stm32f0 board and i try to catch data coming from can bus and answer it back to can bus line. In the begining my program works good but after a couple of minutes mcu stucks in reset(i am not sure of the cause is from software or hardware but 'nrst' pin pulling down to 800mV-1.2V). i need power off and wait 15-30 min, for a reprograming. swd connection errors; 'couldn't be able to stop cortex-m device! Please check the jtag cable'

in my design i made some mistakes such as; nrst pin isn't connected to pull up resistor and pull down capacitor. 

if i change the nrst pin pull up with 10k(or less) and pull down with 100nF will my problem solve? 

there is my custom design and code.

[gunahmt]

any suggestion ???

[gunahmt]

question is in the wrong place or question is so hard ? 

[Alex R]

NRST pin has an weak pullup resistor internally. It is a bidirectional pin.

The external capacitor is recommended to protect the device from parasitic resets.

THe NRST pin is pulled low by the system reset internally.

A system reset is generated when one of the following events occurs:

1. A low level on the NRST pin (external reset)

2. Window watchdog event (WWDG reset)

3. Independent watchdog event (IWDG reset)

4. A software reset (SW reset) (see Software reset)

5. Low-power management reset (see Low-power management reset)

6. Option byte loader reset (see Option byte loader reset)

7. A power reset

Please check you code to see if your program is entering any of these situations.

Do you have implemented Exception Handlers (Hard fault, in particular)?

[gunahmt]

How can i check entering these situations ? i didnt implement exception handlers. I use cubemx for generating library, it cubemx implements hard fault handler? When i working in debug mod, resets kick me out. i didnt handle it.

[gunahmt]

i written a simple code, it transmit data to CANBUS in repeat at 500ms. I set a card, it have dip switch( just 1 switch is on),can transreceiver,power lane, mcu. I set one more card to, it have can transreceiver,power lane and mcu. i remove dip switch identification from board.(other components not placed to boards) After 30 min i check the CANBUS. first card which is have a dip switch is gone to reset. the other card working well... this dip switch connections makes mcu to reset? what is problem? to much ampere on pins? 

hcan.pTxMsg->Data[0] = 'I';
hcan.pTxMsg->Data[1] = 'Y';
hcan.pTxMsg->Data[2] = 'I';
hcan.pTxMsg->DLC = 3;
HAL_CAN_Transmit(&hcan,30);
HAL_Delay(500);

[gunahmt · Accepted solution]

I giving up about can bus. i cant figure it out. i will change the system to rs485 hope mcu don't reset himself again. Hardware or software whatever, that's annoying. Thanks for help.