nrf9160 adc

RE: nrf9160 adc

Håkon Alseth — Tue, 28 Jul 2020 08:57:53 GMT

Hi,

No worries. Glad to hear its working!

It looks like you have a variation of 30 LSB (0x762 - 0x73f).

This could be due to tolerance in resistors and the NTC itself. This can be checked using an oscilloscope on the signal itself to see how much it varies.

Have you tried connecting a constant voltage directly to the ADC pin to see if that also varies?

Kind regards,

Håkon

RE: nrf9160 adc

ephraim — Tue, 28 Jul 2020 06:49:16 GMT

Hi.

You are correct , I am embarrassed .

Now it is working

I change the resolution to 12 bits . #define ADC_RESOLUTION 12

The reading is fluctuates

00> Adc sample 74f
00> Adc sample 74a
00> Adc sample 74b
00> Adc sample 74f
00> Adc sample 749
00> Adc sample 74b
00> Adc sample 74f
00> Adc sample 755
00> Adc sample 73f
00> Adc sample 748
00> Adc sample 74b
00> Adc sample 74d
00> Adc sample 760
00> Adc sample 754
00> Adc sample 75c
00> Adc sample 762
00> Adc sample 760
00> Adc sample 758
00> Adc sample 752
00> Adc sample 747

Please Advise

RE: nrf9160 adc

Håkon Alseth — Mon, 27 Jul 2020 12:42:57 GMT

Hi,

This line looks a bit suspicious:

adc_result = &m_sample_buffer[0];

What type is adc_result? If its not a pointer, you will assign it the address of m_sample_buffer[0]. Based on the printout, it might look like that is the case? Which value does m_sample_buffer hold?

Kind regards,

Håkon