DOUBT IN SAADC EXAMPLE FROM SDK V 14.2.0

[NANDHU]

HI,

       We are developing a 2d -3d  mouse with nRF5_SDK_14.2.0_17b948a  "ble_app_hids_mouse"  application.

• For knowing the battery discharge rate of our product we are trying to implement adc into our code "modified ble_app_hids_mouse ".  
• We are using p0.02(AIN0) for measuring  the battery status.
• Actually our requirement is ,we want to check battery level(i.e adc value) at regular interval of time (may be 1m) and if the battery level is less than 20% we will turn on yellow led and if the battery level is less than 5% the red led will turn on.

For configuring the ADC , I look yours saadc code but i have some doubt in your code .

• I think  in your saadc code they configured ADC ,TIMER AND PPI.

I will explain the flow of code execution what i understood from your saadc below if there is any mistake please correct me

• TIMER will generate an event every 400ms .
• By the help of PPI a task was occurring in SAADC peripheral   due to TIMER event . and its repeating at regular intervals (400 ms)

1. "saadc_callback" function will execute when there is a TIMER event occur , is it right?
2. During the initialization part(saadc_init) "nrf_drv_saadc_buffer_convert" function is calling and also inside the  "saadc_callback" function   is "nrf_drv_saadc_buffer_convert" function is calling . I known these function is for  issuing conversion of data to buffer. Then why its calling on both "saadc_init"  and  "saadc_callback" function.
3. From which buffer we can read the converted analog to digital data ?

please answer to my 1,2 and 3

 if you need any clarification in my question please ask me .

[Håkon Alseth]

NANDHU said:

 I known the functions for Enable SAADC and disable SAADC , then which function is used to wait for the conversion?

That would be the callback handler, with p_evt->type == NRF_DRV_SAADC_EVT_DONE. At this point, the conversion is done.

NANDHU said:

I need some clarification here in Nordic saadc example  during the initialization part i e  "saadc_init " function  they assigning some buffer "m_buffer_pool[0] and m_buffer_pool[1]" and also in the "saadc_callback" function they are doing the same but different buffer "p_event->data.done.p_buffer" and they using this value as adc result too.  Suppose if we take ""m_buffer_pool[0] " or""m_buffer_pool[1] " as adc result what will happen, Is it the same value in the "p_event->data.done.p_buffer" ?

Yes, p_event->data.done.p_buffer will point to the m_buffer_pool array. You can enter debug mode, and look at the pointers, and the global arrays, to see if they match in address to verify this.

 

Kind regards,

Håkon