topic Re: Reading analog data from FRDM KW38 board in Kinetis Microcontrollers

Reading analog data from FRDM KW38 board

notanivipul — Tue, 22 Sep 2020 20:34:40 GMT

Hi,

I am facing trouble in reading analog data from my FRDM KW38 board, I am confused on what bases we select the SDC1 channel and ADC0

Thanks and regards

Vipul

Re: Reading analog data from FRDM KW38 board

kerryzhou — Wed, 23 Sep 2020 04:59:34 GMT

Hi notanivipul,

Do you mean, you don't know which pin for ADC1 and ADC0?

You can check the reference manual, this part:

Then you can check the related pin in RM chapter 3.2 KW39/37 Signal Multiplexing and Pin Assignments

Wish it helps you!
If you still have questions about it, please kindly let me know!
Best Regards,
Kerry
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Re: Reading analog data from FRDM KW38 board

notanivipul — Wed, 23 Sep 2020 05:56:47 GMT

Hi @kerryzhou

According to the reference manual if I am reading data from PTB1 then channel 1 should be assigned for conversion right?

while(1) {

ADC0->SC1[0] = 1;
while (!(ADC0->SC1[0] & 0x80)){}
int res = ADC0->R[0];
PRINTF("%d\n",res);}

is this correct? I have initialized ADC0 before these lines of code and also set PTB1 as analog pin

and my other question is how to do I read 2 analog inputs at the same time? let's say the input pins are PTB1 and PTB3

Thanks and regards

Vipul

Re: Reading analog data from FRDM KW38 board

kerryzhou — Thu, 24 Sep 2020 02:01:52 GMT

Hi notanivipul

Do you also set the ADC0->SC1[0] DIFF bit to 0?

Now, what's the issue you are meeting?

Do you try the SDK code, and modify the channel to ADC channel1:

SDK_2.6.7_FRDM-KW38\boards\frdmkw38\driver_examples\adc16\polling

The SDK can be downloaded from this link:

https://mcuxpresso.nxp.com/

Whether it works or not?

Please try the SDK ADC code at first.

Any updated information, just kindly let me know.

Best Regards,
Kerry
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Re: Reading analog data from FRDM KW38 board

notanivipul — Mon, 28 Sep 2020 06:59:08 GMT

Hi @kerryzhou

Sorry for the late updates

Answering your first question -> yes I have set the DiFF bit to 0.

When I select channel 1 (ADC0->SC1[0] = 1) I am getting values which are continuously varying but when i tried using channel 0(ADC0->SC1[0] = 0) I got stable readings.

For my current project I have to write the drivers on my own that's why i can't use the SDK.

I tried referring the polling example in SDK, but I found it hard to understand.

Thanks and regards

Vipul

Re: Reading analog data from FRDM KW38 board

kerryzhou — Tue, 29 Sep 2020 09:56:05 GMT

HI notanivipul

I mean, you can try the SDK, just modify the channel to your used channel, whether you still have issues or not? If the SDK don't have issues, I think we need to check more details about your code. That doesn't mean you use the SDK driver. Just used for the testing.

So could you please test the SDK on your side when you have time?

Or If you can wait, I will help you to test it after Oct. 9th, as we are taking the National day from tomorrow.

Best Regards,

Kerry