Freescale Semiconductor MCF51QE128RM manual Coco, Input Channel Select, Input Select

Analog-to-Digital Converter (S08ADC12V1)

7 6 5 4

3 2 1 0

R

COCO

AIEN

ADCO

ADCH

W

Reset:

0

0

0

1

1

1

1

1

Figure 11-3. Status and Control Register (ADCSC1)

Table 11-3. ADCSC1 Field Descriptions

Field

Description

7

Conversion Complete Flag. The COCO flag is a read-only bit set each time a conversion is completed when the

COCO

compare function is disabled (ACFE = 0). When the compare function is enabled (ACFE = 1), the COCO flag is

set upon completion of a conversion only if the compare result is true. This bit is cleared when ADCSC1 is written

or when ADCRL is read.

0

Conversion not completed

1

Conversion completed

6

Interrupt Enable AIEN enables conversion complete interrupts. When COCO becomes set while AIEN is high,

AIEN

an interrupt is asserted.

0

Conversion complete interrupt disabled

1

Conversion complete interrupt enabled

5

Continuous Conversion Enable. ADCO enables continuous conversions.

ADCO

0 One conversion following a write to the ADCSC1 when software triggered operation is selected, or one

conversion following assertion of ADHWT when hardware triggered operation is selected.

1 Continuous conversions initiated following a write to ADCSC1 when software triggered operation is selected.

Continuous conversions are initiated by an ADHWT event when hardware triggered operation is selected.

4:0

Input Channel Select. The ADCH bits form a 5-bit field that selects one of the input channels. The input channels

ADCH

are detailed in Table 11-4.

The successive approximation converter subsystem is turned off when the channel select bits are all set. This

feature allows for explicit disabling of the ADC and isolation of the input channel from all sources. Terminating

continuous conversions this way prevents an additional, single conversion from being performed. It is not

necessary to set the channel select bits to all ones to place the ADC in a low-power state when continuous

conversions are not enabled because the module automatically enters a low-power state when a conversion

completes.

Table 11-4. Input Channel Select

ADCH

Input Select

00000–01111

AD0–15

10000–11011

AD16–27

11100

Reserved

11101

VREFH

11110

VREFL

11111

Module disabled

MCF51QE128 MCU Series Reference Manual, Rev. 3

222 Freescale Semiconductor

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