A/D and OSC limitation in PIC16F877 !!!

[arvinfx]

I try to build a voltmeter with PIC. But I found a big limitation, In best condition we must use 4Mhz osc because of "Acquisition Time"! but I need to use 20Mhz osc in my project! Is it true or I had a misunderstanding?

 

[3v0]

You need to read or re-read the datasheet section on the ADC. ADCON0/ADCON1 allow you to set the acquisition time. Are you using the PIC16F877 or PIC16F877A ?

 

[arvinfx]

I am useing PIC16F877A.

I have read the manual one more time, I found that frequency configuration is for "A/D Conversions" not for "Acquisition time" ! Am I understand now?

 

[arvinfx]

I am useing PIC16F877A.

I have read the manual one more time, I found that frequency configuration is for "A/D Conversions" not for "Acquisition time" ! Am I understand now?

 

[Pommie]

The acquisition time is the same whether you use 4MHz or 20MHz.

Mike.