Microcontroller as ADC

[Nigel Goodwin]

Nigel: Using voltage divider will introduce resistance to the system, and thus the system might behave in a wrong way.

Why?, you don't seem to understand what one is?, a correctly designed one causes no problems whatsoever - and they are simple to design.

I will probably make a sample-and-hold block, then do the voltage divider at it's output and sample this output using pic's adc. Or I might just create a source follower, then voltage divide it and then sample this voltage using pic's adc.

No point whatsoever adding an external sample and hold, as it already has an internal one. Why voltage divide AFTER a buffer?, it pretty well negates the point of the buffer, and of the potential divider - check my tutorial hardware, use the buffer between the potential divider and the PIC.

In my case I just want to avoid introducing additional resistors (such as voltage dividers) to the ckt.

Unless your input is 0-5V? (of at least 0-Vref) then there's absolutely no point, and no real alternative!.

 

[williB]

Here is Nigels anlaog input section.