Inconsistent ADC Behaviour with DFU

[eyigiter]

Hi all,

I have a working ADC implementation (S130 + Application) and use it to measure an analog input continuously.

However if I use the same code on top of bootloader (S130+DFU+Application), it starts acting weird. When I check the ADC values, I noticed that they are fluctuating in a large margin. What may cause this issue when I use the code with DFU but works as expected without DFU code?

Regards

[eyigiter]

An additional information: Problem is solved if I connect the analog circuit to NRF_ADC_CONFIG_INPUT_4 instead of NRF_ADC_CONFIG_INPUT_2. So the problem looks related to AIN2 when chip has DFU code. I am still looking for a solution :(

[eyigiter]

Hi Jorgen,

I am using a custom board and I don't use P0.01 for any other purposes. It is only for measuring an analog input. When I check the signal with ossiloscope, I can see the expected waveform on the pin. However as soon as the sampling started it is voltage goes down as shared in the previous image link and returns to the expected level again. It is repeated at all sampling cycle.