RobertD
New Member
Hi folks, I'm still trying to get the AD to give a linear response to input. I changed the pot to RA1 from a 10k to a 5k and got similar responses. That is the ADRESH gives a somewhat logarithmic response, that is top heavy.
0.5v=104
1.0v=189
2.5v=240
3.0v=247
4.4v=254
5.0v=255
You see that it goes from 0.5/104 to 2.5/240, which is the very top of the 255 max for 5v. I'm supposed to get 125 for 2.5v when the response is linear.
I tried with different chips, and I tried with different code, I'm thinking impedance might be a factor, I'm using Firefly/Junebug combo for the programming. I changed the pot from a 10k to a 5k, and seem to get lower values for the ADRESH. I might want to try with a 2k pot for RA3 and see if there is any improvement. But before doing that, I'd like to get some feedback. Maybe try with a different programmer perhaps.
Any suggestions?
(PS: I tried to contact Bill, but he must be on vacation...)
0.5v=104
1.0v=189
2.5v=240
3.0v=247
4.4v=254
5.0v=255
You see that it goes from 0.5/104 to 2.5/240, which is the very top of the 255 max for 5v. I'm supposed to get 125 for 2.5v when the response is linear.
I tried with different chips, and I tried with different code, I'm thinking impedance might be a factor, I'm using Firefly/Junebug combo for the programming. I changed the pot from a 10k to a 5k, and seem to get lower values for the ADRESH. I might want to try with a 2k pot for RA3 and see if there is any improvement. But before doing that, I'd like to get some feedback. Maybe try with a different programmer perhaps.
Any suggestions?
(PS: I tried to contact Bill, but he must be on vacation...)
Last edited: