A/D and OSC limitation in PIC16F877 !!!

A

arvinfx

Member

• Apr 9, 2012

• #1

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

Coop Build Coordinator

Forum Supporter

• Apr 9, 2012

• #2

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 ?

 

A

arvinfx

Member

• Apr 9, 2012

• #3

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?

 

A

arvinfx

Member

• Apr 9, 2012

• #4

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?

 

P

Pommie

Well-Known Member

Most Helpful Member

• Apr 10, 2012

• #5

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

Mike.