xMega bandgap voltage

doncarlos · Joined: 28 Feb 2008 Posts: 29 Location: Szfv.

Hi!

I'd like to measure the battery voltage (using the bandgap voltage) powering my xMega128A1. I tried to search here, I also gone trough the help, but I can't understand how to config my ADC to achieve this . :S

Could somebody write the adc config and the actual command to read the battery voltage? For now I just like to print to the terminal.

Thanks for any help in advance!

Regards,
DC

(BASCOM-AVR version : 2.0.7.8 )

albertsm · Joined: 09 Apr 2004 Posts: 5228 Location: Holland

according to the datasheet, you need to use : Ch0_inp = Internal

MUXPOS[3:0] Group Configuration Description
0000 TEMP Temperature Reference
0001 BANDGAP Bandgap voltage
0010 SCALEDVCC 1/10 scaled Vcc
0011 DAC DAC output

and :

MUXNEG[2:0]
111 INTGND Internal ground

thus :
var=getadc(adca,0,&B1111)
would get the bandgap voltage.

so put/merge this in the getadc sample from the help and it should work.

doncarlos · Joined: 28 Feb 2008 Posts: 29 Location: Szfv.

Hi Mark,

Thanks for the clarification, I was completely on the wrong side.

Now I can measure something with this code:

albertsm · Joined: 09 Apr 2004 Posts: 5228 Location: Holland

you asked for measuring the internal bandgap voltage. But what you want is to read SCALEDVCC. So use &B10_111 instead of &B1111
You then read vcc/10.