Read value on EXT pin thingy 52

[Rilleaa]

Hello.

I having problems with reading a value from one of the ext pins on thingy 52. (i can set the pin as output and toggle the pin from code.)

i have configured the pin as input. 

drv_ext_gpio_cfg_input(SX_IOEXT_1,DRV_EXT_GPIO_PIN_NOPULL);

I want to do something when the pin goes low, iam trying to read the pin value with the function  drv_ext_gpio_pin_read() but i doesent seem to get any reaction when changing from high to low on the pin. I dont really understand the second argument of the function drv_ext_gpio_pin_read() which might be the case why i dont get it to work.

I have tried the following code to check if i get stuck inside the loop when the input pin is high but it just get skipt indicating that the value from drv_ext_gpio_pin_read() is zero.

    while(drv_ext_gpio_pin_read(SX_IOEXT_1,0) != 0   ){

        //do nothing if high

    }

 

Thankful for help. 

//Rilleaa

[Guojun Wang]

Hi Rilleaa,

I think you may have misunderstood the usage of this function drv_ext_gpio_pin_read(uint32_t pin_number, uint32_t * const p_pin). The second argument is passed in to store the pin levels. 

If pin level is read successfully, drv_ext_gpio_pin_read will return DRV_EXT_GPIO_STATUS_CODE_SUCCESS (0x00), otherwise it will return values other than 0.

Once this function returns SUCCESS, then you check the pin level stored in pointer p_pin.

In case it still does not work, you can debug it by setting input pin with PULL UP and read the level again. It should be 1 in this case.

Hope this will help you!

[Rilleaa]

Thank you! 

Yes i must have misunderstood the function and when i did as you recomended the while loop work as i intended. 

Can i ask you another question? 

At the moment i use the function as follows in the code bellow. What i want to do is get data from an adc when new data is ready witch is indicated by pulling the pin low. Would the code bellow be a good way of using the function drv_ext_gpio_pin_read() to wait for that indication that new data is ready or could it be used in a more effict way? 

    uint32_t pinvalue;

    while(pinvalue != 0 ){

        //do nothing
    
        drv_ext_gpio_pin_read(SX_IOEXT_1, &pinvalue);

        
    }

//Rilleaa

[Guojun Wang]

I think it is better to enable pin level interrupt with GPIOTE and make use of interrupt handler to sample the ADC.

In this case, the application doesn't have to actively reading pin levels all the time, and the CPU can go to sleep and only wakes up on interrupt.

[Rilleaa]

Okey thank you very much for the help guwa!

//Rilleaa

[Guojun Wang]

You are welcome!