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 .

[NANDHU]

HI ,

 Suppose i declared a normal array instead of 2D 

i e  "static nrf_saadc_value_t     m_buffer_pool[5];"

and only one buffer assign .i.e please look below screen short

what will happenes. Is this change make any issues in adc convertion?

[Håkon Alseth]

Hi,

 

 

NANDHU said:

Is this change make any issues in adc convertion?

There shouldn't be any issues.

You only provide one buffer, then it will always provide the same RAM pointer into the SAADC peripheral.

 

Kind regards,

Håkon

[NANDHU]

Hi Hakon ,

   Thanks a lot .

Now i got a better clarity  of Nordic "saadc" example.

• Now i want implement this  saadc into our application code. i already told you that we are developing 2d -3d  comp mouse and we are using nRF5_SDK_14.2.0_17b948a  "ble_app_hids_mouse"  application.we modified this application with our own needs.
• I decided to implement adc functionality into our application using TIMER and SAADC module only not using not using PPI.
• Way of working is like below.

1. First we will initialize the  TIMER and SAADC .
2. TIMER is initialized in such a way that ,it will generate an event at every 1 min i.e the execution will enter into the "timer handler function"every 1 min repeatedly.
3. Then inside this "timer handler function" i will call the  saadc functions for starting the saadc sampling i.e nrf_drv_saadc_sample and for read the adc result i.e  nrf_drv_saadc_buffer_convert  
4. After reading the adc data then corresponding led will turn on if the adc result is less than a particular level.

IS THERE ANY ISSUE WITH MY APPROACH ? IF THERE IS  ANY CHANGE NEED PLEASE TELL  ME.

[Håkon Alseth]

As long as you use an app_timer instance (and not a highspeed TIMER, as these draw more current), I do not see any issues.

 

Kind regards,

Håkon

[NANDHU]

HI ,

   In Nordic "saadc" application there is only one channel is configured AIN0 and each time 5 different values are getting from buffer but, if there is no input connected to adc channel ,then who the values are changeing ?