AD output question.

[Pommie]

Eric,
Yes, I got them transposed but miraculously got the correct answer.

Nigel,
Bill specifies 10k pots which are fine as the 88 datasheet states a maximum of 10k input impedance before the acquisition time has to be increased. Besides, the code works as expected on my identical hardware.

I'm now at a loss to explain this and think there must be something else that we're missing.

Mike.

 

[RobertD]

Hi folks, just finished work. so I'm back to work... I used both pots (vr1/vr2) with the same results. I measure the pot on the middle pin, with a meter, and confirm the reading at RA1 or RA3 pin whichever I'm using. I measured the pot resistance to be 2k. The pot is linear, not logarithmic, besides 2volts is 2volts wether logarithmic or not. I'm at a loss also. The code works for you guys which is great, so it's not the code, it should work for me. That's why I think it might be a chip problem, maybe I fried the chip by mistake. I'll try with another chip and see what happens. I'm also thinking of bringing in 5v from outside source and vary it with another pot to see what happens.

Hi Eric, the voltages I give above are measured voltages at the pot slider, which is the same as the pin voltage.

I think my pots are logarithmic, I'll change them.

 

[RobertD]

Come to think of it, the results are logarithmic too... maybe that will make a difference.... I doubt it though. But these pots do get on my nerve being so fickle.

 

[RobertD]

Well if it is not the code, and it's not the chip, then the only other variable is the programmer.

I'll have to either get another programmer, or try to program the chip in circuit using the serial port. And see if I get a different result.