
2004 Microchip Technology Inc.
Preliminary
DS39637A-page 247
PIC18F2480/2580/4480/4580
19.0
10-BIT ANALOG-TO-DIGITAL
CONVERTER (A/D) MODULE
The Analog-to-Digital (A/D) converter module has
8 inputs for the PIC18F2X80 devices and 11 for the
PIC18F4X80 devices. This module allows conversion
of an analog input signal to a corresponding 10-bit
digital number.
The module has five registers:
A/D Result High Register (ADRESH)
A/D Result Low Register (ADRESL)
A/D Control Register 0 (ADCON0)
A/D Control Register 1 (ADCON1)
A/D Control Register 2 (ADCON2)
The ADCON0 register, shown in Register 19-1,
controls the operation of the A/D module. The
ADCON1 register, shown in Register 19-2, configures
the functions of the port pins. The ADCON2 register,
shown in Register 19-3, configures the A/D clock
source, programmed acquisition time and justification.
REGISTER 19-1:
ADCON0: A/D CONTROL REGISTER 0
U-0
U-0
R/W-0
—
—
CHS3
bit 7
R/W-0
CHS2
R/W-0
CHS1
R/W-0
CHS0
R/W-0
GO/DONE
R/W-0
ADON
bit 0
bit 7-6
bit 5-2
Unimplemented:
Read as ‘
0
’
CHS3:CHS0:
Analog Channel Select bits
0000
= Channel 0 (AN0)
0001
= Channel 1 (AN1)
0010
= Channel 2 (AN2)
0011
= Channel 3 (AN3)
0100
= Channel 4 (AN4)
0101
= Channel 5 (AN5)
(1,2)
0110
= Channel 6 (AN6)
(1,2)
0111
= Channel 7 (AN7)
(1,2)
1000
= Channel 8 (AN8)
1001
= Channel 9 (AN9)
1010
= Channel 10 (AN10)
1011
= Unused
1100
= Unused
1101
= Unused
1110
= Unused
1111
= Unused
Note 1:
These channels are not implemented on PIC18F2X80 devices.
2:
Performing a conversion on unimplemented channels will return full-scale
measurements.
bit 1
GO/DONE:
A/D Conversion Status bit
When ADON =
1
:
1
= A/D conversion in progress
0
= A/D Idle
ADON:
A/D On bit
1
= A/D converter module is enabled
0
= A/D converter module is disabled
bit 0
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