PIC18F87J93 Microchip Technology, PIC18F87J93 Datasheet - Page 33

• Manufacturer Part Number: PIC18F87J93
• Description: LCD PIC18F Microcontroller
• Manufacturer: Microchip Technology

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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 2.1
“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 2-2:
© 2009 Microchip Technology Inc.
Configure the A/D module:
• Configure analog pins, voltage reference and
• Select A/D input channel (ADCON0)
• Select A/D acquisition time (ADCON2)
• Select A/D conversion clock (ADCON2)
• Turn on A/D module (ADCON0)
digital I/O (ADCON1)
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
Preliminary
PIC18F87J93 FAMILY
I
±100 nA
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 ADIF bit, 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
= 25 pF
DS39948A-page 31
(kΩ)
4
AD
is