jbritt@hobbes.catt.ncsu.edu (Joe Britt) (11/29/90)
Help! A friend of mine just got one of those 68HC11 evaluation boards from Motorola. One project idea we had for it needs the A/D converter, so we decided to try hooking up a potentiometer as a voltage divider just for initial experimentation. We connected VrefHI to +5v and VrefLO to ground. We connected one side of the pot to +5, the other side to ground, and the center lug tothe A/D input (Port E, bit 0). Then we wrote this simple little program to grab bytes from the A/D converter and dump them out to the terminal port. We get stuff from the converter, but it looks screwy. Looking at the pot's output with a voltmeter, we see a nice (LINEAR) swing from 0 to 5v. What we see on the terminal screen though, is usually one of 2 values: AA or 55. Sometimes it won't be so distinct, and it will oscillate between several values. The program is super-simple: once the a/d is set up, it waits (counts down from $ff), grabs a sample, then counts down again. What are we missing? Has anyone successfully used the a/d converter on one of these boards? muchos thanks in advance, jbritt@eceugs.ncsu.edu -- << jbritt@hobbes.catt.ncsu.edu >> No Other Possibility. You're going to have to shoplift from SafeMuffins. Yes, you're going to have to shoplift the HR Steamcleaning System from SafeMuffins....