Chapter 5

Configuration Register (CONFIG)

5.1 Introduction

This section describes the configuration register (CONFIG). This register contains bits that configure these options:

•Resets caused by the low-voltage inhibit (LVI) module

•Power to the LVI module

•Computer operating properly (COP) module

•Top-side pulse-width modulator (PWM) polarity

•Bottom-side PWM polarity

•Edge-aligned versus center-aligned PWMs

•Six independent PWMs versus three complementary PWM pairs

5.2 Functional Description

The configuration register (CONFIG) is used in the initialization of various options. The configuration register can be written once after each reset. All of the configuration register bits are cleared during reset. Since the various options affect the operation of the microcontroller unit (MCU), it is recommended that this register be written immediately after reset. The configuration register is located at $001F and may be read at anytime.

NOTE

On a FLASH device, the options are one-time writeable by the user after each reset. The registers are not in the FLASH memory but are special registers containing one-time writeable latches after each reset. Upon a reset, the configuration register defaults to predetermined settings as shown in Figure 5-1.

If the LVI module and the LVI reset signal are enabled, a reset occurs when

VDD falls to a voltage, VLVRx, and remains at or below that level for at least nine consecutive central processor unit (CPU) cycles. Once an LVI reset

occurs, the MCU remains in reset until VDD rises to a voltage, VLVRX.

MC68HC908MR32 • MC68HC908MR16 Data Sheet, Rev. 6.1

Freescale Semiconductor

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Freescale Semiconductor MC68HC908MR16, MC68HC908MR32 manual Chapter Configuration Register Config, Introduction
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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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