 |
 |
| View previous topic :: View next topic |
| Author |
Message |
starbuck
Joined: 21 Jan 2009
Posts: 6
|
| A/D Converter on PIC16F886 |
 Posted: Tue Feb 03, 2009 2:59 pm |
 |
|
I am having a problem reading the internal AtoD converter on a PIC16F886. It appears when I look at the value in ADCON0 that the wrong input is being selected when I do a "set_adc_channel( x );"
I have looked at the 16F886.h file and it appears that I am using the correct constants to setup the ports and clock:
setup_adc_ports( sAN2 |sAN3 | sAN4 | VSS_VDD );
setup_adc( ADC_CLOCK_INTERNAL );
When I have selected look at ADCON0 it is set to a value of 0x11101001 (0xE9) which based on the PIC16F88x data sheet would indicate that I have selected AN10 not AN2 as I would expect.
Has anyone elese experienced this problem?
I am using PCM 4.085
Here is my source code:
| Code: | // ADC TEST
// Test code for PIC16F886 A to D Converter
// Compiler CCS PCM version 4.085
#include <16F886.H>
#device ICD = TRUE
#device *=16 ADC=10
#fuses HS, NOWDT, NOPROTECT, BROWNOUT, PUT, NOLVP
#use delay(clock=20000000)
#zero_ram
//===============================
void main()
{
long AD_Ch_2 = 0;
long AD_Ch_3 = 0;
long AD_Ch_4 = 0;
// Setup PortA I/O
Set_Tris_A(0b011110); //sets up port A as an input port
//init A/D converter
setup_adc_ports( sAN2 |sAN3 | sAN4 | VSS_VDD );
setup_adc( ADC_CLOCK_INTERNAL );
while(1)
{
set_adc_channel( PIN_A2 ); // ADC2 (RA2)
delay_us(10); // Delay to allow stabilization
AD_Ch_2 = read_adc(); // Get the AtoD value
set_adc_channel( PIN_A3 ); // ADC3 (RA3)
delay_us(10); // Delay to allow stabilization
AD_Ch_2 = read_adc(); // Get the AtoD value
set_adc_channel( PIN_A4 ); // ADC4 (RA4)
delay_us(10); // Delay to allow stabilization
AD_Ch_2 = read_adc(); // Get the AtoD value
delay_ms(500);
}
} |
|
|
 |
PCM programmer
Joined: 06 Sep 2003
Posts: 21708
|
|
| Posted: Tue Feb 03, 2009 3:16 pm |
|
|
| Quote: | set_adc_channel( PIN_A2 );
set_adc_channel( PIN_A3 );
set_adc_channel( PIN_A4 ); |
From the manual:
http://www.ccsinfo.com/downloads/ccs_c_manual.pdf
| Quote: | Syntax: set_adc_channel (chan)
Parameters: 'chan' is the channel number to select.
Channel numbers start at 0 and are labeled in the data sheet AN0, AN1 |
ie., do not use Pin constants for channels. Use 0, 1, 2, 3, etc. for the
channel. |
|
|
starbuck
Joined: 21 Jan 2009
Posts: 6
|
| OK - Read the Manual not just look at it! |
| Posted: Tue Feb 03, 2009 3:44 pm |
|
|
Works fine, Thanks again PCM
Another case of staring at the manual too long!
Here is my revised code for the record:
| Code: |
// ADC TEST
// Test code for PIC16F886 A to D Converter
// Compiler CCS PCM version 4.085
#include <16F886.H>
#device ICD = TRUE
#device *=16 ADC=10
#fuses HS, NOWDT, NOPROTECT, BROWNOUT, PUT, NOLVP
#use delay(clock=20000000)
#zero_ram
//===============================
void main()
{
long AD_Ch_2 = 0;
long AD_Ch_3 = 0;
long AD_Ch_4 = 0;
// Setup PortA I/O
Set_Tris_A(0b011110); //sets up port A as an input port
//init A/D converter
setup_adc_ports( sAN2 |sAN3 | sAN4 | VSS_VDD );
setup_adc( ADC_CLOCK_INTERNAL );
while(1)
{
set_adc_channel( 2 ); // ADC2 (RA2)
delay_us(20); // Delay to allow stabilization
AD_Ch_2 = read_adc(); // Get the AtoD value
set_adc_channel( 3 ); // ADC3 (RA3)
delay_us(20); // Delay to allow stabilization
AD_Ch_3 = read_adc(); // Get the AtoD value
set_adc_channel( 4 ); // ADC4 (RA4)
delay_us(20); // Delay to allow stabilization
AD_Ch_4 = read_adc(); // Get the AtoD value
delay_ms(500);
}
} |
|
|
|
|
|
You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot vote in polls in this forum
|
Powered by phpBB © 2001, 2005 phpBB Group
|
FAQ 
Search
Register
Profile 
Log in to check your private messages 
Log in
