A/D resolution problem

ElectroNick · Joined: 10 Oct 2005 Posts: 4

Hello,

I'm using PIC16F946 and trying to use ADC.

My problem is the ADC result is 8 bit instead of 10 bit.

ckielstra · Joined: 18 Mar 2004 Posts: 3680 Location: The Netherlands

From the PICC manual for the Read_ADC() function:

PCM programmer · Joined: 06 Sep 2003 Posts: 21708

For a 10-bit A/D, if you use #device adc=16, the compiler
will left-justify the result. i.e., the max reading will be
formated as 0xFFC0. Most people want a right-justified
result, to format it as 0x03FF. To do this, you should use
#device adc=10. The manual has the following chart
in the read_adc() section:

raj · Guest

I am seeing the posts on 10 bit ADc problems but no solutions.
I had configured
#device adc=10

and i am using 16 bit variable
int16 reading

still i get the maximum value as 255.

How do I get 10 bit value?

PCM programmer · Joined: 06 Sep 2003 Posts: 21708

1. What PIC are you using ?

2. What is your compiler version ?

The compiler version is given at the top of the .LST file, which is
in your project folder. It will be a number like 3.191, 3.245, etc.

kj · Guest

Hello,

I'm using PIC16F946
My problem is the data type compilling.

#include "16f946.h"
//#include "16f877.h"

#FUSES HS,WDT,BROWNOUT,NOPROTECT,PUT,NODEBUG,CPD,MCLR,NOFCMEN
#ZERO_RAM
#use delay(clock=20000000,restart_wdt)
.
.
bit run_chk_flag,sec_chk_flag,key_chk_flag;
if include 16f877 file ; not problem
if include 16f946 file ; "expeciting a ( "message appeared at bit position

What do you think about this, what is the problem?

I use:
MPLAB IDE v7.30
PCWH Compiler
IDE Version 3.249
PCB Version 3.249
PCM Version 3.249
PCH Version 3.249

Ttelmah · Guest

There is no inherent 'bit' datatype in CCS. There is an 'int1', which is a single bit, and the '#bit' directive, which allows a int1, to be mapped to a fixed location. This is why the compile fails.
The reason it works for the 877, is that your version of the include file for this, contains a line like:
#define bit int1

This is not standard (there is normally one for 'boolean', as int1, and one for 'byte' as int8), but somehow the version you have has had this line included.

Best Wishes