Issues with analogRead when using Vin on Arduino
Issues with analogRead when using Vin on Arduino
(OP)
Hello,
I am having hardware specific problems with analogRead when I am supplying power via the Vin pin on an Arduino MKR1000 (https://www.arduino.cc/en/Main/ArduinoMKR1000) — It’s an Atmel SAMD21.
Attached is a very simple voltage divider circuit
that should always return a value around 2047 when I am using 12 bit ADC resolution of pin A2. This is indeed the case when I am supplying power via USB - either directly to the computer or USB charger device.
But when I am using the Vin pin via an external source
then the ADC values are 1954 - 1890 —> around 100 values lower! I have no explanation for this and the Vcc of 3.3 is not changing if I use either way of supplying power.
(In case you are wondering: I am sending the ADC values via Wifi to the computer in both power supply methods)
What could be the source of this?
Thanks
Markus
I am having hardware specific problems with analogRead when I am supplying power via the Vin pin on an Arduino MKR1000 (https://www.arduino.cc/en/Main/ArduinoMKR1000) — It’s an Atmel SAMD21.
Attached is a very simple voltage divider circuit
that should always return a value around 2047 when I am using 12 bit ADC resolution of pin A2. This is indeed the case when I am supplying power via USB - either directly to the computer or USB charger device.But when I am using the Vin pin via an external source
then the ADC values are 1954 - 1890 —> around 100 values lower! I have no explanation for this and the Vcc of 3.3 is not changing if I use either way of supplying power.
(In case you are wondering: I am sending the ADC values via Wifi to the computer in both power supply methods)
What could be the source of this?
Thanks
Markus





RE: Issues with analogRead when using Vin on Arduino
TTFN (ta ta for now)
I can do absolutely anything. I'm an expert! https://www.youtube.com/watch?v=BKorP55Aqvg
FAQ731-376: Eng-Tips.com Forum Policies forum1529: Translation Assistance for Engineers Entire Forum list http://www.eng-tips.com/forumlist.cfm
RE: Issues with analogRead when using Vin on Arduino
Two different GNDs?
RE: Issues with analogRead when using Vin on Arduino
I am connected to the USB shield which has a ferrite bead (BLM18PG471SN1D) in line with it.
RE: Issues with analogRead when using Vin on Arduino
EEVblog #441 - How To Track Down Common Mode Noise
https://www.youtube.com/watch?v=BFLZm4LbzQU
I find this guy pretty entertaining, sometimes I listen to random videos of his while I work.