M68HC08 datasheet(159/288 Pages) FREESCALE

159 / 288 page

Analog-to-Digital Converter (ADC)

MC68HC908BD48 — Rev. 2.1

Data Sheet

Freescale Semiconductor

Analog-to-Digital Converter (ADC)

159

AIEN — ADC Interrupt Enable Bit

When this bit is set, an interrupt is generated at the end of an ADC

conversion. The interrupt signal is cleared when the data register is

read or the status/control register is written. Reset clears the AIEN bit.

1 = ADC interrupt enabled

0 = ADC interrupt disabled

ADCO — ADC Continuous Conversion Bit

When set, the ADC will convert samples continuously and update the

ADR register at the end of each conversion. Only one conversion is

allowed when this bit is cleared. Reset clears the ADCO bit.

1 = Continuous ADC conversion

0 = One ADC conversion

ADCH[4:0] — ADC Channel Select Bits

ADCH[4:0] form a 5-bit field which is used to select one of the ADC

channels. The five channel select bits are detailed in the following

table. Care should be taken when using a port pin as both an analog

and a digital input simultaneously to prevent switching noise from

corrupting the analog signal. (See Table 12-2.)

The ADC subsystem is turned off when the channel select bits are all

set to one. This feature allows for reduced power consumption for the

MCU when the ADC is not used. Reset sets all of these bits to a

logic 1.

NOTE:

Recovery from the disabled state requires one conversion cycle to

stabilize.

M68HC08 Datasheet(PDF) 159 Page - Freescale Semiconductor, Inc