PIC18F25J11-I/PT MICROCHIP [Microchip Technology], PIC18F25J11-I/PT Datasheet - Page 349

• Manufacturer Part Number: PIC18F25J11-I/PT
• Description: 28/44-Pin, Low-Power, High-Performance Microcontrollers with nanoWatt XLP Technology
• Manufacturer: MICROCHIP [Microchip Technology]

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 20.1
“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.
The following steps should be followed to do an A/D
conversion:
1.
FIGURE 20-2:
© 2009 Microchip Technology Inc.
Configure the A/D module:
• Configure the required ADC pins as analog
• Set voltage reference using ADCON0
• Select A/D input channel (ADCON0)
• Select A/D acquisition time (ADCON1)
• Select A/D conversion clock (ADCON1)
• Turn on A/D module (ADCON0)
pins using ANCON0, ANCON1
Legend: C
V
AIN
R
S
V
I
R
SS
C
R
LEAKAGE
T
PIN
IC
HOLD
SS
ANALOG INPUT MODEL
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
DD
V
V
T
T
= 0.6V
= 0.6V
I
±100 nA
PIC18F46J11 FAMILY
LEAKAGE
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 (if required).
Start conversion:
• Set GO/DONE bit (ADCON0<1>)
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.
≤ 1k
SS
Sampling
Switch
V
DD
AD
R
SS
. A minimum wait of 2 T
Sampling Switch
1
V
SS
C
2
HOLD
3
DS39932C-page 349
= 25 pF
(kΩ)
4
AD
is