PIC18F2458 datasheet(21/46 Pages) MICROCHIP

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Preliminary

DS39887B-page 19

PIC18F2458/2553/4458/4553

2.0

12-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-pin

and 44-pin devices. This module allows conversion of an

analog input signal to a corresponding 12-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 2-1, controls

the operation of the A/D module. The ADCON1

functions of the port pins. The ADCON2 register,

shown in Register 2-3, configures the A/D clock

source, programmed acquisition time and justification.

ADCON0: A/D CONTROL REGISTER 0

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.

Performing a conversion on unimplemented channels will return a floating input measurement.

PIC18F2458 Datasheet(PDF) 21 Page - Microchip Technology

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