MC68HC908RF2CFA Freescale Semiconductor, MC68HC908RF2CFA Datasheet - Page 100

• Manufacturer Part Number: MC68HC908RF2CFA
• Description: IC MCU W/UHF TX 2K FLASH 32LQFP
• Manufacturer: Freescale Semiconductor
• Series: HC08r

Specifications of MC68HC908RF2CFA

• Core Processor: HC08
• Core Size: 8-Bit
• Speed: 4MHz
• Peripherals: LVD, POR, PWM, RF Mod
• Number Of I /o: 12
• Program Memory Size: 2KB (2K x 8)
• Program Memory Type: FLASH
• Ram Size: 128 x 8
• Voltage - Supply (vcc/vdd): 1.8 V ~ 3.6 V
• Oscillator Type: Internal
• Operating Temperature: -40°C ~ 85°C
• Package / Case: 32-LQFP
• Lead Free Status / RoHS Status: Contains lead / RoHS non-compliant
• Eeprom Size: -
• Data Converters: -
• Connectivity: -

Keyboard/External Interrupt Module (KBI)
7.3.5 Keyboard Initialization
7.4 Low-Power Modes
7.4.1 Wait Mode
7.4.2 Stop Mode
Data Sheet
100
NOTE:
Setting a keyboard interrupt enable bit (KBIE<x>) forces the corresponding
keyboard interrupt pin to be an input, overriding the data direction register.
However, the data direction register bit must be a 0 for software to read the pin.
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:
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:
The WAIT and STOP instructions put the MCU in low power-consumption standby
modes.
The IRQ1/keyboard interrupts remain active in wait mode. Clearing the IMASKI or
IMASKK bits in the IRQ and keyboard status and control register enables keyboard
interrupt requests to bring the MCU out of wait mode.
The IRQ1/keyboard interrupt remains active in stop mode. Clearing the IMASKI or
IMASKK bit in the IRQ and keyboard status and control register enables keyboard
interrupt requests to bring the MCU out of stop mode.
1. Mask keyboard interrupts by setting the IMASKK bit in the keyboard status
2. Enable the KBI pins by setting the appropriate KBIEx bits in the keyboard
3. Write to the ACKK bit in the keyboard status and control register to clear any
4. Clear the IMASKK bit.
1. Configure the keyboard pins as outputs by setting the appropriate DDRA
2. Write 1s to the appropriate port A data register bits.
3. Enable the KBI pins by setting the appropriate KBIEx bits in the keyboard
and control register.
interrupt enable register.
false interrupts.
bits in data direction register A.
interrupt enable register.
Freescale Semiconductor, Inc.
For More Information On This Product,
Keyboard/External Interrupt Module (KBI)
Go to: www.freescale.com
MC68HC908RF2 — Rev. 4.0
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