Fault Protection

12.6 Fault Protection

Conditions may arise in the external drive circuitry which require that the PWM signals become inactive immediately, such as an overcurrent fault condition. Furthermore, it may be desirable to selectively disable PWM(s) solely with software.

One or more PWM pins can be disabled (forced to their inactive state) by applying a logic high to any of the four external fault pins or by writing a logic high to either of the disable bits (DISX and DISY in PWM control register 1). Figure 12-26shows the structure of the PWM disabling scheme. While the PWM pins are disabled, they are forced to their inactive state. The PWM generator continues to run — only the output pins are disabled.

To allow for different motor configurations and the controlling of more than one motor, the PWM disabling function is organized as two banks, bank X and bank Y. Bank information combines with information from the disable mapping register to allow selective PWM disabling. Fault pin 1, fault pin 2, and PWM disable bit X constitute the disabling function of bank X. Fault pin 3, fault pin 4, and PWM disable bit Y constitute the disabling function of bank Y. Figure 12-25and Figure 12-27show the disable mapping write-once register and the decoding scheme of the bank which selectively disables PWM(s). When all bits of the disable mapping register are set, any disable condition will disable all PWMs.

A fault can also generate a CPU interrupt. Each fault pin has its own interrupt vector.

Address:

$0037

 

 

 

 

 

 

 

 

Bit 7

6

5

4

3

2

1

Bit 0

Read:

 

 

 

 

 

 

 

 

Bit 7

Bit 6

Bit 5

Bit 4

Bit 3

Bit 2

Bit 1

Bit 0

Write:

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Reset:

1

1

1

1

1

1

1

1

Figure 12-25. PWM Disable Mapping Write-Once Register (DISMAP)

12.6.1 Fault Condition Input Pins

A logic high level on a fault pin disables the respective PWM(s) determined by the bank and the disable mapping register. Each fault pin incorporates a filter to assist in rejecting spurious faults. All of the external fault pins are software-configurable to re-enable the PWMs either with the fault pin (automatic mode) or with software (manual mode). Each fault pin has an associated FMODE bit to control the PWM re-enabling method. Automatic mode is selected by setting the FMODEx bit in the fault control register. Manual mode is selected when FMODEx is clear.

MC68HC908MR32 • MC68HC908MR16 Data Sheet, Rev. 6.1

Freescale Semiconductor

137

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Freescale Semiconductor MC68HC908MR16, MC68HC908MR32 manual Fault Protection, Fault Condition Input Pins
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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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