LPC15xx ADC readings

Discussion created by lpcware Employee on Jun 15, 2016
Latest reply on Jun 15, 2016 by lpcware
Content originally posted in LPCWare by kbowers on Thu Aug 28 10:52:42 MST 2014
I am having some issues with the accuracy of the ADC readings on the LPC1549 using the Xpresso V2 board.  I am sampling several inputs using burst mode and am seeing relatively accurate readings on ADC1 but not on ADC0 (about 10% high)  The driving circuitry on all the channels are almost identical.

I have run the calibration cycle on both ADC0 and ADC1 and all the setup configurations are identical.

Is it possible that ADC0 is damaged?  Can I select channel 0 to be the temperature on both ADC's and compare the values to confirm they are both working correctly?

I was also wondering what the VDDA/2 input to channel 0 should read.  Should it not just be 2048 or is there a formula to convert the ADC reading to an actual voltage for VDDA/2.