checking the value on a pin

[ganeshredcobra]

Hello am using stm32f4 discovery board along with chibios.... i need to check whether the value of that pin is high or low.....
i need to know how can check that condition in chibios...

[Giovanni]

Hi,

It is palReadPad(), there is an example in main.c into the STM32F4-Discovery demo, it checks the button state:

/*
* If the user button is pressed after the reset then the test suite is
* executed immediately before activating the various device drivers in
* order to not alter the benchmark scores.
*/
if (palReadPad(GPIOA, GPIOA_BUTTON))
TestThread(&SD2);

The pin must be programmed as input of course.

Giovanni

[ganeshredcobra]

Thank you will check that

[ganeshredcobra]

Hi Giovanni,
This is the code i used

palSetPadMode(GPIOD, GPIOD_LED3, PAL_MODE_OUTPUT_PUSHPULL); /* Green. */
palSetPadMode(GPIOA, GPIOA_BUTTON,PAL_MODE_INPUT);

if (palReadPad(GPIOA, GPIOA_BUTTON))
{
palSetPad(GPIOD, GPIOD_LED3);
}

but its not working can you rectify me is there any option to use like this

if (palReadPad(GPIOA, GPIOA_BUTTON)==HIGH)

[Giovanni]

The code is correct but verify that the button is actually pressed while executing the palReadPad() functio.

If you are working with the default discovery board files there is no need to program the pins, the board files already do that for you. Changing the pin settings is only required if you need a setting different from the default one.

Giovanni

[ganeshredcobra]

But its not working...just like above said can i use HIGH or LOW option....can you post a sample code to read input from a switch and blink led...If am using an external switch what must be the input voltage given..

[Giovanni]

if you are reading GPIOA_BUTTON it is unlikely you will ever read your external switch, you mush specify the correct port and pin.

Giovanni

[ganeshredcobra]

What are the other basic tutorials that beginners can try on to understand the coding style of chibios

[Giovanni]

The documentation page is here:

http://www.chibios.org/dokuwiki/doku.ph ... :documents

Look for the HAL reference manual.

Then there are all the examples under ./demos and ./testhal in the source distribution.

Giovanni

[lawrenceais]

I got same problem with the STM32F4-Discovery demo. I spent several hours to look for solution. And also, registered an account to ask for solution.

It also displaying error during debug:
----------------------------------
Thu Aug 02, 2012 01:36:22: The stack pointer for stack 'CSTACK' (currently 0x20000400) is outside the stack range (0x2001FC00 to 0x20020000)
----------------------------------

Finally, I found out ...... I always treat the "Reset" button as the input of "GPIOA_BUTTON".