參數(shù)資料
型號(hào)： MC68HC08LT8CFGE
廠商： FREESCALE SEMICONDUCTOR INC
元件分類： 微控制器/微處理器
英文描述： 8-BIT, MROM, 4 MHz, MICROCONTROLLER, PQFP44
封裝： 10 X 10 MM, 1.40 MM THICKNESS, 0.80 MM PITCH, ROHS COMPLIANT, MS-026BCB, LQFP-44
文件頁數(shù)： 17/156頁
文件大?。?/td> 1107K
代理商： MC68HC08LT8CFGE
Keyboard Interrupt Registers
MC68HC08LT8 Data Sheet, Rev. 1
Freescale Semiconductor
113
If the MODEK bit is clear, the keyboard interrupt pin is falling-edge-sensitive only. With MODEK clear, a
vector fetch or software clear immediately clears the keyboard interrupt request.
Reset clears the keyboard interrupt request and the MODEK bit, clearing the interrupt request even if a
keyboard interrupt pin stays at logic 0.
The keyboard flag bit (KEYF) in the keyboard status and control register can be used to see if a pending
interrupt exists. The KEYF bit is not affected by the keyboard interrupt mask bit (IMASKK) which makes
it useful in applications where polling is preferred.
To determine the logic level on a keyboard interrupt pin, disable the pull-up device, use the data direction
register to configure the pin as an input and then read the data register.
NOTE
Setting a keyboard interrupt enable bit (KBIEx) 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.
11.4.1 Keyboard Initialization
When a keyboard interrupt pin is enabled, it takes time for the internal pull-up 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 IMASKK bit in the keyboard status and control register.
2.
Enable the KBI pins by setting the appropriate KBIEx bits in the keyboard interrupt enable register.
3.
Write to the ACKK bit in the keyboard status and control register to clear any false interrupts.
4.
Clear the IMASKK bit.
An interrupt signal on an edge-triggered pin can be acknowledged immediately after enabling the pin. An
interrupt signal on an edge- and level-triggered interrupt pin must be acknowledged after a delay that
depends on the external load.
Another way to avoid a false interrupt:
1.
Configure the keyboard pins as outputs by setting the appropriate DDRA bits in the data direction
register A.
2.
Write logic 1’s to the appropriate port A data register bits.
3.
Enable the KBI pins by setting the appropriate KBIEx bits in the keyboard interrupt enable register.
11.5 Keyboard Interrupt Registers
Two registers control the operation of the keyboard interrupt module:
Keyboard status and control register
Keyboard interrupt enable register
相關(guān)PDF資料
PDF描述
MC68HC11G5CFN 8-BIT, MROM, 2.1 MHz, MICROCONTROLLER, PQCC84
MC68HC11G5CFN 8-BIT, MROM, 2.1 MHz, MICROCONTROLLER, PQCC84
MC68HC11L6VFU23 8-BIT, MROM, 3 MHz, MICROCONTROLLER, PQFP64
MC68HC11L6CFU22 8-BIT, MROM, 2 MHz, MICROCONTROLLER, PQFP64
MC68HC11L6VFU22 8-BIT, MROM, 2 MHz, MICROCONTROLLER, PQFP64
相關(guān)代理商/技術(shù)參數(shù)
參數(shù)描述
MC68HC08MR4 制造商:MOTOROLA 制造商全稱:Motorola, Inc 功能描述:In-Circuit Simulator
MC68HC08P4 制造商:FREESCALE 制造商全稱:Freescale Semiconductor, Inc 功能描述:HCMOS MICROCONTROLLER UNIT
MC68HC08QT1 制造商:FREESCALE 制造商全稱:Freescale Semiconductor, Inc 功能描述:M68HC08 Microcontrollers
MC68HC08QT2 制造商:FREESCALE 制造商全稱:Freescale Semiconductor, Inc 功能描述:M68HC08 Microcontrollers
MC68HC08QT4 制造商:FREESCALE 制造商全稱:Freescale Semiconductor, Inc 功能描述:M68HC08 Microcontrollers
發(fā)布緊急采購，3分鐘左右您將得到回復(fù)。

采購需求

(若只采購一條型號(hào)，填寫一行即可)

發(fā)布成功！您可以繼續(xù)發(fā)布采購。也可以進(jìn)入我的后臺(tái)，查看報(bào)價(jià)

發(fā)布成功！您可以繼續(xù)發(fā)布采購。也可以進(jìn)入我的后臺(tái)，查看報(bào)價(jià)

*型號(hào) *數(shù)量 廠商 批號(hào) 封裝
添加更多采購

我的聯(lián)系方式

*
*
*