PIC18FXX8 Datasheet, PDF (243/402 Pages) Microchip Technology – 28/40-Pin High-Performance, Enhanced Flash Microcontrollers with CAN Module

PIC18FXX8
20.0 COMPATIBLE 10-BIT ANALOG-
TO-DIGITAL CONVERTER (A/D)
MODULE
The Analog-to-Digital (A/D) Converter module has five
inputs for the PIC18F2X8 devices and eight for the
PIC18F4X8 devices. This module has the ADCON0
and ADCON1 register definitions that are compatible
with the PICmicro^® mid-range A/D module.
The A/D allows conversion of an analog input signal to
a corresponding 10-bit digital number.
The A/D module has four registers. These registers are:
• A/D Result High Register (ADRESH)
• A/D Result Low Register (ADRESL)
• A/D Control Register 0 (ADCON0)
• A/D Control Register 1 (ADCON1)
The ADCON0 register, shown in Register 20-1,
controls the operation of the A/D module. The
ADCON1 register, shown in Register 20-2, configures
the functions of the port pins.
REGISTER 20-1: ADCON0: A/D CONTROL REGISTER 0
R/W-0 R/W-0 R/W-0 R/W-0 R/W-0
R/W-0
U-0
ADCS1 ADCS0 CHS2
CHS1
CHS0 GO/DONE
—
bit 7
R/W-0
ADON
bit 0
bit 7-6
ADCS1:ADCS0: A/D Conversion Clock Select bits (ADCON0 bits in bold)
ADCON1
ADCON0
<ADCS2> <ADCS1:ADCS0>
Clock Conversion
0
00
FOSC/2
0
01
FOSC/8
0
10
FOSC/32
0
11
FRC (clock derived from the internal A/D RC oscillator)
1
00
FOSC/4
1
01
FOSC/16
1
10
FOSC/64
1
11
FRC (clock derived from the internal A/D RC oscillator)
bit 5-3
bit 2
bit 1
bit 0
CHS2:CHS0: Analog Channel Select bits
000 = Channel 0 (AN0)
001 = Channel 1 (AN1)
010 = Channel 2 (AN2)
011 = Channel 3 (AN3)
100 = Channel 4 (AN4)
101 = Channel 5 (AN5)⁽¹⁾
110 = Channel 6 (AN6)⁽¹⁾
111 = Channel 7 (AN7)⁽¹⁾
Note 1: These channels are unimplemented on PIC18F2X8 (28-pin) devices. Do not select
any unimplemented channel.
GO/DONE: A/D Conversion Status bit
When ADON = 1:
1 = A/D conversion in progress (setting this bit starts the A/D conversion which is automatically
cleared by hardware when the A/D conversion is complete)
0 = A/D conversion not in progress
Unimplemented: Read as ‘0’
ADON: A/D On bit
1 = A/D converter module is powered up
0 = A/D converter module is shut-off and consumes no operating current
Legend:
R = Readable bit
-n = Value at POR
W = Writable bit
‘1’ = Bit is set
U = Unimplemented bit, read as ‘0’
‘0’ = Bit is cleared x = Bit is unknown
 2004 Microchip Technology Inc.
DS41159D-page 241