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]

Also may it still be a hardware issue when the problem occurs when I transmit the package over DFU only? Without DFU, it works as expected.

Edit: In my previous messages, I have posted the following image and marked the HIGH value as expected analog value but now I noticed that it is not correct. Expected analog value must be at 1V level, but in the image it is about 3V.

pasteboard.co/GK23FHl.jpg

So to summarize the issue:

1. When we load the application on top of S130 by using nrfGo, it works as expected (we can measure the analog signal about 1V)
2. When we load the application on top of S130+DFU by using NRF Toolbox, analog signal goes to 3V level during normal operation which should have been 1V actually, and draws a wavesquare each time ADC sampling occurs. Once the ADC sampling stopped, it goes to 3V level again. May it be an internal pullup-pulldown issue during ADC sampling?