PIC16F7X7
The value in the ADRESH/ADRESL registers is not
modified for a Power-on Reset. The ADRESH/
ADRESL registers will contain unknown data after a
Power-on Reset.
2. Configure A/D interrupt (if desired):
• Clear ADIF bit
• Set ADIE bit
• Set PEIE bit
After the A/D module has been configured as desired,
the selected channel must be acquired before the
conversion is started. The analog input channels must
have their corresponding TRIS bits selected as an
input. To determine acquisition time, see Section 12.1
“A/D Acquisition Requirements”. After this acquisi-
tion time has elapsed, the A/D conversion can be
started. An acquisition time can be programmed to
occur between setting the GO/DONE bit and the actual
start of the conversion.
• Set GIE bit
3. Wait the required acquisition time (if required).
4. Start conversion:
• Set GO/DONE bit (ADCON0 register)
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 registers (ADRESH:ADRESL);
clear bit ADIF (if required).
The following steps should be followed to do an A/D
conversion:
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.
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 acquisition time (ADCON2)
• Select A/D conversion clock (ADCON0)
• Turn on A/D module (ADCON0)
FIGURE 12-1:
A/D BLOCK DIAGRAM
CHS<3:0>
1101
AN13
1100
AN12
1011
AN11
0011
AN3/VREF+
0010
VIN
AN2/VREF-
0001
(Input Voltage)
AN1
0000
VDD
AN0
A/D
Converter
VREF+
(Reference
Voltage)
VCFG<1:0>
VREF-
(Reference
Voltage)
VSS
VCFG<1:0>
2004 Microchip Technology Inc.
DS30498C-page 155
MICROCHIP [ MICROCHIP ]
