PIC18C658 MICROCHIP [Microchip Technology], PIC18C658 Datasheet - Page 231

• Manufacturer Part Number: PIC18C658
• Description: High-Performance Microcontrollers with CAN Module
• Manufacturer: MICROCHIP [Microchip Technology]

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.
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 18.1.
After this acquisition time has elapsed, the A/D conver-
sion can be started. The following steps should be fol-
lowed to do an A/D conversion:
1.
FIGURE 18-2: ANALOG INPUT MODEL
2000 Microchip Technology Inc.
Configure the A/D module:
• Configure analog pins, voltage reference and
• Select A/D input channel (ADCON0)
• Select A/D conversion clock (ADCON2)
• Turn on A/D module (ADCON0)
digital I/O (ADCON1)
Legend: C
V
AIN
Rs
V
I
R
SS
C
R
LEAKAGE
T
PIN
IC
HOLD
SS
ANx
C
5 pF
PIN
= input capacitance
= threshold voltage
= leakage current at the pin due to
= interconnect resistance
= sampling switch
= sample/hold capacitance (from DAC)
= sampling switch resistance
various junctions
V
Advanced Information
DD
V
V
T
T
= 0.6 V
= 0.6 V
I leakage
± 500 nA
2.
3.
4.
5.
6.
7.
R
IC
Configure A/D interrupt (if desired):
• Clear ADIF bit
• Set ADIE bit
• Set GIE bit
Wait the required acquisition time.
Start conversion:
• Set GO/DONE bit (ADCON0 register)
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
Read A/D Result registers (ADRESH:ADRESL);
clear bit ADIF, if required.
For next conversion, go to step 1 or step 2, as
required. The A/D conversion time per bit is
defined as T
required before next acquisition starts.
1 k
V
SS
DD
Sampling
Switch
6V
5V
4V
3V
2V
R
AD
SS
. A minimum wait of 2T
PIC18CXX8
Sampling Switch
5 6 7 8 9 10 11
V
SS
C
HOLD
= 120 pF
DS30475A-page 231
( k )
AD
is