•Return of all enabled keyboard interrupt pins to logic 1 — As long as any enabled keyboard interrupt pin is at logic 0, the keyboard interrupt remains set.

The vector fetch or software clear and the return of all enabled keyboard interrupt pins to logic 1 may occur in any order.

If the MODED bit is clear, the keyboard interrupt pin is falling-edge-sensitive only. With MODED clear, a vector fetch or software clear immediately clears the keyboard interrupt request.

Reset clears the keyboard interrupt request and the MODED bit, clearing the interrupt request even if a keyboard interrupt pin stays at logic 0.

The keyboard flag bit (KEYDF) in the keyboard status and control register can be used to see if a pending interrupt exists. The KEYDF bit is not affected by the keyboard interrupt mask bit (IMASKD) which makes it useful in applications where polling is preferred.

To determine the logic level on a keyboard interrupt pin, use the data direction register to configure the pin as an input and read the data register.

NOTE: Setting a keyboard interrupt enable bit (KBDIEx) forces the corresponding keyboard interrupt pin to be an input, overriding the data direction register. However, the data direction register bit must be a logic 0 for software to read the pin.

15.4.2 Port-D Keyboard Initialization

When a keyboard interrupt pin is enabled, it takes time for the internal pullup to reach a logic 1. Therefore a false interrupt can occur as soon as the pin is enabled.

To prevent a false interrupt on keyboard initialization:

1.Mask keyboard interrupts by setting the IMASKD bit in the keyboard status and control register.

2.Enable the KBI pins by setting the appropriate KBDIEx bits in the keyboard interrupt enable register.

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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