topic Re: How can we decide the exact values for the ADC Attributes?? in Kinetis Microcontrollers

How can we decide the exact values for the ADC Attributes??

omkardixit — Tue, 19 Jan 2021 06:10:28 GMT

I was working on the "TWR-K70120M" in which I was trying to understand the "LWADC" example which I found on the following path "C:\Freescale\Freescale_MQX_4_1\mqx\examples\lwadc\build\uv4\lwadc_twrk70f120m".

So, while debugging I observed one thing that there is one function which is printing all the attributes on the uart

print_all_lwadc_attributes(&potentiometer); (image is attached below)

So, now I really want to know how we can decide exact values for the ADC attributes??. Also, I already have gone through the readme.pdf file but unfortunately, it wasn't mentioned there. Can anyone please help me to understand this?.

Regards

Omkar Dixit

Re: How can we decide the exact values for the ADC Attributes??

danielchen — Sat, 23 Jan 2021 03:11:11 GMT

Hi omkardixit:

We get the real attribute value through API _lwad_read_raw()

mqx/source/io/lwadc/lwadc_vadc.c

/*FUNCTION*-------------------------------------------------------------------
*
* Function Name : _lwadc_read_raw
* Returned Value : TRUE for success, FALSE for failure
* Comments :
* This function Read the current value of the ADC input and return
* the result without applying any scaling.
*
*END*----------------------------------------------------------------------*/

bool _lwadc_read_raw(LWADC_STRUCT_PTR lwadc_ptr, LWADC_VALUE_PTR outSample)
{
ADC_MemMapPtr adc_ptr;
LWADC_VALUE sample;

if (NULL == lwadc_ptr){
return FALSE;
}

if (lwadc_ptr->context_ptr == NULL) {
return FALSE;
}
adc_ptr = lwadc_ptr->context_ptr->adc_ptr;

if ((adc_ptr->GC & ADC_GC_ADCO_MASK) == 0) {
/* ADC is not in continuous mode. */
adc_ptr->GC |= ADC_GC_ADCO_MASK;
}

sample = adc_ptr->R[0];

*outSample = sample & ADC_CDR_CDATA_MASK;

return TRUE;
}

Regards

Daniel

Re: How can we decide the exact values for the ADC Attributes??

omkardixit — Sat, 23 Jan 2021 04:51:52 GMT

Hi Daniel,

Thanks for your reply. Yes, I have tried the API you mentioned. If you see the image which I have uploaded, consists of the ADC attributes eg. LWADC_FORMAT, LWADC_DIVIDER, and more.

So, my dought is except the LWADC_RESOLUTION & LWADC_FREQUNCY attributes how can we decide the values of the other attributes. If in the case of my next project again I need to work with ADC so how can I decide the values of the attributes?.

Regards

Omkar Dixit

Re: How can we decide the exact values for the ADC Attributes??

danielchen — Wed, 31 Mar 2021 08:34:30 GMT

From the source code, the other attributes values are initialized in function _lwadc_init () , mqx/source/io/lwadc/lwadc_vadc.c line 47