
PIC18F2450/4450
2006 Microchip Technology Inc.
Advance Information
DS39760A-page 173
16.0
10-BIT ANALOG-TO-DIGITAL
CONVERTER (A/D) MODULE
The Analog-to-Digital (A/D) converter module has
10 inputs for the 28-pin devices and 13 for the 40/44-pin
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
controls the operation of the A/D module. The
the functions of the port pins. The ADCON2 register,
source, programmed acquisition time and justification.
REGISTER 16-1:
ADCON0: A/D CONTROL REGISTER 0
U0
U-0
R/W-0
—
CHS3
CHS2
CHS1
CHS0
GO/DONE
ADON
bit 7
bit 0
Legend:
R = Readable bit
W = Writable bit
U = Unimplemented bit, read as ‘0’
-n = Value at POR
‘1’ = Bit is set
‘0’ = Bit is cleared
x = Bit is unknown
bit 7-6
Unimplemented: Read as ‘0’
bit 5-2
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
= Channel 11 (AN11)
1100
= Channel 12 (AN12
1101
= Unimplemented(2)
1110
= Unimplemented(2)
1111
= Unimplemented(2)
bit 1
GO/DONE: A/D Conversion Status bit
When ADON = 1:
1
= A/D conversion in progress
0
= A/D Idle
bit 0
ADON: A/D On bit
1
= A/D converter module is enabled
0
= A/D converter module is disabled
Note 1:
These channels are not implemented on 28-pin devices.
2:
Performing a conversion on unimplemented channels will return a floating input measurement.