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Unread 06-03-2011, 17:24
mandrews281 mandrews281 is offline
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Cypress Board Analog Input Help Needed

I'm seeing something very strange with the analog inputs on J2/J3 on our Cypress IO board. I have a potentiometer wired so that Pin 1 on J2 (VDDIO) is on one side of the pot and pin 14 (GND) is on the other end of the pot.. Pin2/P0_0/AI1 is connected to the potentiometer wiper. I'm watching the IO tab on the driver station as I move the wiper, AI1 is steady at about 50%, but _all_ the other analog inputs (AI2-AI8) follow the potentiometer. When I attach the wiper to AI3, AI1-AI3 are steady and AI4-AI8 follow the wiper. I've put a volt meter between the wiper and ground and it's acting exactly as I'd expect -- voltage varying continuously between 0-3.3V. What am I doing wrong?

Here's some addition information: (1) I'm watching all this in the driver station software. There is no robot active, (2) The board has been setup up in enhanced IO mode with all 16 digital ports configured as pulled down inputs. (3) I have flashed the board with the V2 hex file. (4) I've borrowed a second board from another local team and saw the exact same behaviour on that board. (5) J1 and J4 are jumpered for 3.3V -- basically I haven't touched them.

Thanks in advance
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Michael Andrews
Team #281 Programming Mentor
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