CAI_Support said:Hi Ross,
R12 and R13 both 100K divide the analog input for humidity sensor. If you like to change that by replace R12 to 200K or change R13 to 50K, then they will be 10V full scale. Please note once change made to those resistors, humidity sensor will no longer provide meaningful result.
You will need to add protection for analog input, since microprocessor's analog input does not take much current.
Thanks, that's fine.
I don't like to modify the boards unless its absolutely necessary. NOT changing the boards means that I can swap them out to either faultfind, or to send them away for upgrade or whatever. Also, external solutions make for generic designs others can use.
My current thinking is that your 2:1 divider is fine now that I know what's there. If I drive it from an opamp, via a small resistor lets say 1K, and a 6.8V zener to ground on the terminal board, it should clamp the input to the chip itself at 3.4V which should be safe.
The advantage with this is other people can use the WebAmp board too, without needing to modify THEIR webcontrol boards (and no potential warranty problems with modified boards).
Now I just need to think if I'm better using two webcontrol boards and some inter-board communications, or making a multiplexer on the analog input. I am not sure there are too many people will need 8 A/D inputs, so that may make that board "too specific".