AT89C51AC3-RDTIM datasheet(108/143 Pages) ATMEL

108 / 143 page

108

AT89C51AC3

4383B–8051–01/05

Figure 61. A/D Converter clock

ADC Standby Mode

When the ADC is not used, it is possible to set it in standby mode by clearing bit ADEN

in ADCON register. In this mode its power dissipation is about 1 µW.

IT ADC Management

An interrupt end-of-conversion will occurs when the bit ADEOC is activated and the bit

EADC is set. For re-arming the interrupt the bit ADEOC must be cleared by software.

Figure 62. ADC Interrupt Structure

Routines examples

1. Configure P1.2 and P1.3 in ADC channels

// configure channel P1.2 and P1.3 for ADC

ADCF = 0Ch

// Enable the ADC

ADCON = 20h

2. Start a standard conversion

// The variable "channel" contains the channel to convert

// The variable "value_converted" is an unsigned int

// Clear the field SCH[2:0]

ADCON and = F8h

// Select channel

ADCON | = channel

// Start conversion in standard mode

ADCON | = 08h

// Wait flag End of conversion

while((ADCON and 01h)! = 01h)

// Clear the End of conversion flag

ADCON and = EFh

// read the value

value_converted = (ADDH << 2)+(ADDL)

3. Start a precision conversion (need interrupt ADC)

// The variable "channel" contains the channel to convert

// Enable ADC

Prescaler ADCLK

A/D

Converter

ADC Clock

CPU

CLOCK

CPU Core Clock Symbol

÷ 2

ADEOC

ADCON.2

EADC

IEN1.1

ADCI

AT89C51AC3-RDTIM Datasheet(PDF) 108 Page - ATMEL Corporation

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