MC908QT4MPE datasheet(45/184 Pages) FREESCALE

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Input/Output Signals

MC68HC908QY/QT Family Data Sheet, Rev. 5

Freescale Semiconductor

3.5.2 Stop Mode

The ADC module is inactive after the execution of a STOP instruction. Any pending conversion is aborted.

ADC conversions resume when the MCU exits stop mode. Allow one conversion cycle to stabilize the

analog circuitry before using ADC data after exiting stop mode.

3.6 Input/Output Signals

The ADC module has four channels that are shared with I/O port A.

ADC voltage in (ADCVIN) is the input voltage signal from one of the four ADC channels to the ADC

module.

3.7 Input/Output Registers

These I/O registers control and monitor ADC operation:

•

ADC status and control register (ADSCR)

•

ADC data register (ADR)

•

ADC clock register (ADICLK)

3.7.1 ADC Status and Control Register

The following paragraphs describe the function of the ADC status and control register (ADSCR). When a

conversion is in process and the ADSCR is written, the current conversion data should be discarded to

prevent an incorrect reading.

COCO — Conversions Complete Bit

In non-interrupt mode (AIEN = 0), COCO is a read-only bit that is set at the end of each conversion.

COCO will stay set until cleared by a read of the ADC data register. Reset clears this bit.

In interrupt mode (AIEN = 1), COCO is a read-only bit that is not set at the end of a conversion. It

always reads as a 0.

1 = Conversion completed (AIEN = 0)

0 = Conversion not completed (AIEN = 0) or CPU interrupt enabled (AIEN = 1)

NOTE

The write function of the COCO bit is reserved. When writing to the ADSCR

Address: $003C

Bit 7

654321

Bit 0

Read:

COCO

AIEN

ADCO

CH4

CH3

CH2

CH1

CH0

Write:

Reset:

00011111

R= Reserved

Figure 3-3. ADC Status and Control Register (ADSCR)

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