STM32F0 Comparator Output issue

[jim_jones188]

Posted on September 02, 2016 at 19:53

I am unable to get any output from the COMP1 comparator on an STM32F072RB on any pin other than PA0. The datasheet ''STM32F072x8 STM32F072xB'' states on pg 41 that COMP1_OUT should be available on pins PA0 PA6 and PA11 through the alternate function channels.

I have tried developing my own code writing directly to the registers with CMSIS, and also modifying the low level examples (Examples_LL) from the STM32CubeF0 for the STM32F072RB-Nucleo. Specifically the ''COMP_CompareGpioVsVrefInt_OutputGpio'' example.

Has anyone ran into this issue or does anyone know a fix?

[Walid FTITI_O]

Posted on September 05, 2016 at 13:40

Hi jones.jim.002,

I have made a quick test on the Nucelo-F072 using the example that you mentionned. All COMP_OUT pins works well and the example is OK. Just ensure the following:

* For case PA6 as COMP_OUT pin :

- Replace all ''LL_GPIO_PIN_0'' with ''LL_GPIO_PIN_6''

* For case PA11 as COMP_OUT pin :

-Replace all ''LL_GPIO_PIN_0'' with ''LL_GPIO_PIN_11''

- Replace fucntion ''LL_GPIO_SetAFPin_0_7'' with ''LL_GPIO_SetAFPin_8_15''

-Hannibal-

[jim_jones188]

Posted on September 06, 2016 at 18:10

Thank you for the response Hannibal.

In the example listed I changed line 143 to:

 ''LL_GPIO_SetPinOutputType(GPIOA, LL_GPIO_PIN_11, LL_GPIO_OUTPUT_PUSHPULL);'',

line 146 to:

''LL_GPIO_SetPinSpeed(GPIOA, LL_GPIO_PIN_11, LL_GPIO_SPEED_FREQ_VERY_HIGH);'',

line 149 to:

''LL_GPIO_SetPinMode(GPIOA, LL_GPIO_PIN_11, LL_GPIO_MODE_ALTERNATE);,

and line 150 to:

''LL_GPIO_SetAFPin_8_15(GPIOA, LL_GPIO_PIN_11, LL_GPIO_AF_7);''

It still doesn't work for me and as when I change everything back to pin 0 it works correctly. Either I am missing something, or I have defective/damaged silicon because I get nothing for either pin 6 or pin 11.

[Walid FTITI_O]

Posted on September 06, 2016 at 18:26

Hi,

Don't forget to make change inside the while(1) like folllowing :

if (LL_GPIO_IsInputPinSet(GPIOA, LL_GPIO_PIN_11) != 0)
{
LED_On();
}
else
{
LED_Off();
}

-Hannibal-

[jim_jones188]

Posted on September 06, 2016 at 20:29

I tried to change this as well. It still doesn't seem to work.

[Walid FTITI_O]

Posted on September 22, 2016 at 12:23

Hi jones.jim.002,

Are you testing that on the ready-to-use example of STM32Cube. If yes, you surely hardware issue , try to change the NUCLEO by other one and see.

-Hannibal-