2001 Microchip Technology Inc.
DS30292C-page 113
PIC16F87X
These steps should be followed for doing an A/D
Conversion:
1.
Configure the A/D module:
Configure analog pins/voltage reference and
digital I/O (ADCON1)
Select A/D input channel (ADCON0)
Select A/D conversion clock (ADCON0)
Turn on A/D module (ADCON0)
2.
Configure A/D interrupt (if desired):
Clear ADIF bit
Set ADIE bit
Set PEIE bit
Set GIE bit
3.
Wait the required acquisition time.
4.
Start conversion:
Set GO/DONE bit (ADCON0)
5.
Wait for A/D conversion to complete, by either:
Polling for the GO/DONE bit to be cleared
(with interrupts enabled); OR
Waiting for the A/D interrupt
6.
Read
A/D
result
register
pair
(ADRESH:ADRESL), clear bit ADIF if required.
7.
For the next conversion, go to step 1 or step 2,
as required. The A/D conversion time per bit is
defined as TAD. A minimum wait of 2TAD is
required before the next acquisition starts.
FIGURE 11-1:
A/D BLOCK DIAGRAM
(Input Voltage)
VAIN
VREF+
(Reference
Voltage)
VDD
PCFG3:PCFG0
CHS2:CHS0
RE2/AN7(1)
RE1/AN6(1)
RE0/AN5(1)
RA5/AN4
RA3/AN3/VREF+
RA2/AN2/VREF-
RA1/AN1
RA0/AN0
111
110
101
100
011
010
001
000
A/D
Converter
Note
1: Not available on PIC16F873/876 devices.
VREF-
(Reference
Voltage)
VSS
PCFG3:PCFG0