Datasheet

 1997 Microchip Technology Inc. DS30390E-page 119
PIC16C7X
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 diagrams of the A/D module are
shown in Figure 13-3.
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 13.1.
After this acquisition time has elapsed the A/D conver-
sion can be started. The following steps should be fol-
lowed 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 T
AD. A minimum wait of 2TAD is
required before next acquisition starts.
FIGURE 13-3: A/D BLOCK DIAGRAM
(Input voltage)
VIN
VREF
(Reference
voltage)
V
DD
PCFG2:PCFG0
CHS2:CHS0
000 or
010 or
100
001 or
011 or
101
RE2/AN7
(1)
RE1/AN6
(1)
RE0/AN5
(1)
RA5/AN4
RA3/AN3/VREF
RA2/AN2
RA1/AN1
RA0/AN0
111
110
101
100
011
010
001
000
A/D
Converter
Note 1: Not available on PIC16C72/73/73A/76.