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 51 Page 53
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Image 52
Freescale Semiconductor MC68HC908MR32, MC68HC908MR16 manual ADC Status and Control Register, Aien ADC Interrupt Enable Bit
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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.

One of the standout features of the MC68HC908MR series is its CMOS technology, which enhances performance while minimizing power consumption. This makes these microcontrollers suitable for battery-operated devices. They operate at a maximum clock frequency of 2 MHz and offer a 16-bit architecture, providing a solid balance between processing power and efficiency.

The MC68HC908MR32 variant is equipped with 32KB of flash memory, which allows for the storage of complex programs and extensive data handling. In contrast, the MC68HC908MR16 features 16KB of flash memory, making it ideal for simpler applications. Both microcontrollers also come with 1KB of RAM, enabling efficient data processing and real-time operations.

Another significant characteristic of these microcontrollers is their integrated peripherals. They come with multiple input/output (I/O) pins, which allow for connectivity with various sensors and actuators. The built-in timer systems offer precise timing control for automotive and industrial applications, while the Analog-to-Digital Converter (ADC) provides essential conversion capabilities for various analog signals.

For communication purposes, the MC68HC908MR series includes a serial communication interface, enabling easy integration with other devices and systems. This versatility facilitates the development of complex systems that require interaction with external components.

Security is another crucial aspect of these microcontrollers. They have built-in fail-safe mechanisms to ensure reliable operation under various conditions, making them suitable for critical systems. Additionally, their robust architecture helps to safeguard against potential disruptions or attacks.

In summary, Freescale Semiconductor's MC68HC908MR32 and MC68HC908MR16 microcontrollers are key players in the embedded systems landscape. Their blend of power efficiency, integrated features, and scalability ensures they remain relevant for a wide array of applications, making them a favored choice among engineers and developers looking for dependable solutions in a competitive market.
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