Scott Engel

16 bit microcontroller ATD questions

Discussion created by Scott Engel on Sep 19, 2006
Latest reply on Jan 21, 2008 by Valdir Sousa
I would like to ask someone about some particulars of the ATD system on MC9S12E128.
I am reading the registers as right justified, 10 bit, unsigned and not getting what I expect.
The VCC of the micro is 3V but the VRH and VRL range is 4.0V.
I placed 3 volts at the input of a channel  (under emulator control ) but am reading 2.5V.
By my calculation I'm about a half a volt off on my readings, though they are fairly consistent.
If I ground the input, it reads close to zero most of the time, within 3%.
Any suggestions?
Eagle Beak