14.4 Functional Description

A logic zero applied to the external interrupt pin can latch a CPU interrupt request. Figure 14-1shows the structure of the IRQ module.

Interrupt signals on the IRQ1/VPP pin are latched into the IRQ1 latch. An interrupt latch remains set until one of the following actions occurs:

•Vector fetch — A vector fetch au tomatically generates an interrupt acknowledge signal that clears the IRQ latch.

•Software clear — Software can clea r the interrupt latch by writing to the acknowledge bit in the interrupt status and control register (ISCR). Writing a logic one to the ACK1 bit clears the IRQ1 latch.

• Reset — A reset automatically clears the interrupt latch.

The external interrupt pin is falling-edge-triggered and is software- configurable to be either falling-edge or low-level-triggered. The MODE1 bit in the ISCR controls the triggering sensitivity of the IRQ1/VPP pin.

When the interrupt pin is edge-triggered only, the CPU interrupt request remains set until a vector fetch, software clear, or reset occurs.

When the interrupt pin is both falling-edge and low-level-triggered, the

CPU interrupt request remains set until both of the following occur:

•Vector fetch or software clear

•Return of the interrupt pin to logic one

The vector fetch or software clear may occur before or after the interrupt pin returns to logic one. As long as the pin is low, the interrupt request remains pending. A reset will clear the latch and the MODE1 control bit, thereby clearing the interrupt even if the pin stays low.

When set, the IMASK1 bit in the ISCR mask all external interrupt requests. A latched interrupt request is not presented to the interrupt priority logic unless the IMASK1 bit is clear.

NOTE: The interrupt mask (I) in the condition code register (CCR) masks all interrupt requests, including external interrupt requests.(See 7.6 Exception Control.)

Advance Information

MC68HC(7)08KH12 — Rev. 1.1

 

 

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MC68HC08KH12 specifications

The Freescale Semiconductor MC68HC08KH12 is a versatile microcontroller that has gained popularity in various embedded systems applications. Part of the HC08 family, this microcontroller combines a robust architecture with comprehensive on-chip features, making it suitable for a wide range of applications ranging from industrial control to consumer electronics.

One of the main features of the MC68HC08KH12 is its 8-bit architecture, which provides an optimal balance between performance and power efficiency. It operates at clock speeds of up to 2 MHz, allowing for efficient execution of instructions while maintaining low power consumption. The microcontroller is designed to operate over a voltage range of 2.7 to 5.5 volts, making it adaptable to various system requirements.

The MC68HC08KH12 is equipped with 1 Kbyte of RAM and 12 Kbytes of ROM, which allows for substantial program and data storage. The on-chip memory helps reduce the need for external components, simplifying the design of embedded systems and enhancing reliability. With a wide range of I/O options, including 26 general-purpose I/O pins, the microcontroller provides flexibility in interfacing with sensors, actuators, and other devices.

In terms of technologies, the MC68HC08KH12 features an advanced instruction set that enhances programming efficiency. It supports basic arithmetic operations, bit manipulation, and control transfer instructions, making it suitable for a variety of computational tasks. The integrated timers, analog-to-digital converters, and serial communication interfaces, including UART, provide the necessary tools for real-time control and data exchange with peripheral devices.

Another characteristic of the MC68HC08KH12 is its low power mode capabilities, which allow it to enter a sleep state during periods of inactivity. This feature is essential in battery-powered applications, where minimizing power consumption is crucial for extending operational life.

Overall, the Freescale Semiconductor MC68HC08KH12 stands out as a reliable microcontroller that combines performance, flexibility, and power efficiency. Its extensive features and technologies enable engineers to design robust embedded systems that meet the demands of modern applications. As a result, the MC68HC08KH12 remains a valuable choice for developers seeking a highly functional yet cost-effective microcontroller solution.
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