NetBurner Community Forum

Posted: **Mon Feb 17, 2014 3:17 pm**

Hello NB community,

I have been developing a project with the MOD54415 & the MOD-Dev-70 1.9 development board. I'm experiencing a strange phenomenon and I hope someone here will be able to explain it.

I've boiled down the problem to a use-case.

Init ADC Single Ended
Read ADC_IN5, get value X
POWER UP DAC
Read ADC_IN5, get value X+unexplained offset

The problem is that as soon as I power-up my DACs, some ADCs seem to get affected somehow.

Here is the source code to my use case :

main.cpp: Use case reproducing the problem; (3.03 KiB) Downloaded 636 times

If I let the J2[11] (ADC_IN5) pin floating, the program output is:

Code: Select all

ADC_IN5 With DACs Powered On
(1127) 0.918989 V

ADC_IN5 With DACs Powered Off
(22) 0.017939 V

If I set the pin to about 1.1 V (with a simple divider), the program output is:

Code: Select all

ADC_IN5 With DACs Powered On
(1656) 1.350352 V

ADC_IN5 With DACs Powered Off
(1356) 1.105723 V

So you see there is still an offset, and it seems to be induced by the powering-up of the DACs.

Any idea what could be causing this? I have tried it on 3 different MOD54415 boards.

Thanks for your support NB community...!

NetBurner Community Forum

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