VBAT_Mesurement STM32V207 unusual results

[hhosburg]

Posted on May 08, 2012 at 18:13

Hello,

I've used the code from the example VBAT_Mesurement to test the ADC. Instead of connecting a  battery on pin VBAT I've connected VDD 3.3V. The program requests cyclic the converted value. .... VBATVoltage = (ADCConvertedValue*2)*3300/0xFFF; ... VBATVoltage  varies from 3287 to 2992. this is a difference  about 8 percent. I've checked the power VDD with an oscilloscope , which  is quit clean. There are no peaks visible. Does anybody know the reason for this ? Regards, Harald

[Tesla DeLorean]

Posted on May 08, 2012 at 21:44

Does anybody know the reason for this ?

Using 15 cycle mode I'm seeing +/- 20%, this drops below +/- 1% in 480 cycle mode. ADC_SampleTime_480Cycles

[hhosburg]

Posted on May 09, 2012 at 07:36

Thanks,

it works Harald