PIC16F72-E Datasheet, PDF (56/136 Pages) Microchip Technology – 28-Pin, 8-Bit CMOS FLASH Microcontoller with A/D Converter

PIC16F72
REGISTER 10-2:
ADCON1: A/D CONTROL REGISTER 1 (ADDRESS 9Fh)
U-0
U-0
U-0
U-0
U-0
R/W-0
—
—
—
—
—
PCFG2
bit 7
R/W-0
PCFG1
R/W-0
PCFG0
bit 0
bit 7-3
bit 2-0
Unimplemented: Read as ‘0’
PCFG<2:0>: A/D Port Configuration Control bits
PCFG2:PCFG0
000
001
010
011
100
101
11x
A = Analog input
RA0 RA1 RA2
A
A
A
A
A
A
A
A
A
A
A
A
A
A
D
A
A
D
D
D
D
D = Digital I/O
RA5
A
A
A
A
D
D
D
RA3
A
VREF
A
VREF
A
VREF
D
VREF
VDD
RA3
VDD
RA3
VDD
RA3
VDD
Legend:
R = Readable bit
- n = Value at POR
W = Writable bit
‘1’ = Bit is set
U = Unimplemented bit, read as ‘0’
‘0’ = Bit is cleared x = Bit is unknown
The ADRES register contains the result of the A/D con-
version. When the A/D conversion is complete, the
result is loaded into the ADRES register, the GO/DONE
bit (ADCON0<2>) is cleared, and A/D interrupt flag bit
ADIF is set. The block diagram of the A/D module is
shown in Figure 10-1.
The value in the ADRES register is not modified for a
Power-on Reset. The ADRES register will contain
unknown data after a Power-on Reset.
After the A/D module has been configured as desired,
the selected channel must be acquired before the con-
version is started. The analog input channels must
have their corresponding TRIS bits selected as an
input. To determine acquisition time, see Section 10.1.
After this acquisition time has elapsed, the A/D
conversion can be started.
The following 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 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
OR
• Waiting for the A/D interrupt
6. Read A/D Result register (ADRES), clear bit
ADIF if required.
7. For 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 2 TAD is
required before the next acquisition starts.
DS39597C-page 54
© 2007 Microchip Technology Inc.