Hi, I am monitoring some sensors which provide 0V to 10V output. I have two 4.7K resistors as a divider and all seemed OK but the accuracy was poor. I set the OPTION_REG bit 7 to turn off the internal pull-ups but no good. Some meassurements and calculations indicate the 10k internal resistor is still present.
With 8 bit resolution I get 255 at 10V but 51 at 0V. I am certain the 10K pull-ups are not diabled but after going over the data sheet a number of times I can't find how to disable them, other than option_reg. I am using portA to display on LCD and have tried ADCIN 5, val and ADCIN 6, val but both have pull-ups to Vdd.
Any suggestions please.
Steve