Analog-to-Digital Converter (ADC)

3.7.1 ADC Status and Control Register

This section describes the function of the ADC status and control register (ADSCR). Writing ADSCR aborts the current conversion and initiates a new conversion.

Address:

$0040

 

 

 

 

 

 

 

 

Bit 7

6

5

4

3

2

1

Bit 0

 

 

 

 

 

 

 

 

 

Read:

COCO

AIEN

ADCO

ADCH4

ADCH3

ADCH2

ADCH1

ADCH0

 

 

Write:

R

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Reset:

0

0

0

1

1

1

1

1

 

 

 

 

 

 

 

 

 

 

R

= Reserved

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Figure 3-4. ADC Status and Control Register (ADSCR)

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 register, always have a 0 in the COCO bit position.

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

ADCH4, ADCH3, ADCH2, ADCH1, and ADCH0 form a 5-bit field which is used to select one of 10 ADC channels. The ADC channels are detailed in Table 3-1.

NOTE

Take care to prevent switching noise from corrupting the analog signal when simultaneously using a port pin as both an analog and digital input.

The ADC subsystem is turned off when the channel select bits are all set to 1. This feature allows for reduced power consumption for the MCU when the ADC is not used.

NOTE

Recovery from the disabled state requires one conversion cycle to stabilize.

MC68HC908MR32 • MC68HC908MR16 Data Sheet, Rev. 6.1

52

Freescale Semiconductor

Page 52
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Freescale Semiconductor MC68HC908MR32, MC68HC908MR16 manual ADC Status and Control Register, Aien ADC Interrupt Enable Bit

MC68HC908MR16, MC68HC908MR32 specifications

Freescale Semiconductor's MC68HC908MR32 and MC68HC908MR16 microcontrollers are part of the popular HC08 family, designed primarily for embedded applications. These microcontrollers are particularly favored in automotive, industrial, and consumer product sectors due to their reliability and versatility.

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