adc high resolution with pic16f877A

[john120]

Hello everybody,I would like to take measurements of voltage of 0.005V using PIC16F877A in ccs c compiler,how can I proceed for reading that very small voltage I am using the attached circuits for push buttons implementation;so can you plz help me to think on this?I am suing the special buttons which are not reacting when I use the ordinary push buttons connection techniques as attached here on the second schematic.


.View attachment Schematic.zip ordinary push buttons:View attachment Buttons.zip


Thanks

 

[blueroomelectronics]

Amplify the voltage with an OpAmp.

 

[embpic]

It depend on reference voltage also so keep reference voltage minimum.

 

[paulfjujo]

hello,

Minimum range -Vref to +Vref is 1,5V or (2V official) so with 1024 points =>2mV/point
What is the speed acquisition nb of measure per second ?
if you are not hurry, you can use external high resolution ADC like :
more details and source C18 on my web page.

 

[jayanth.devarayanadurga]

He is not using it to measure adc value. He has a strange keypad connection which is placing 0.005V at the pin of uC and it is not working as the voltage is below VIH for a digital input pin to read the key. So, he wants to use adc to measure the 0.005V which appears at the uC pin when key is pressed. His strange button interface is shown in his another thread.

 

[embpic]

Will you plz explain..

 

[jayanth.devarayanadurga]

https://www.edaboard.com/threads/290936/