MC68HC908JB16DW Freescale Semiconductor, MC68HC908JB16DW Datasheet - Page 293

• Manufacturer Part Number: MC68HC908JB16DW
• Description: IC MCU 16K FLASH 6MHZ USB 28SOIC
• Manufacturer: Freescale Semiconductor
• Series: HC08r

Specifications of MC68HC908JB16DW

• Core Processor: HC08
• Core Size: 8-Bit
• Speed: 6MHz
• Connectivity: SCI, USB
• Peripherals: LED, LVD, POR, PWM
• Number Of I /o: 21
• Program Memory Size: 16KB (16K x 8)
• Program Memory Type: FLASH
• Ram Size: 384 x 8
• Voltage - Supply (vcc/vdd): 4 V ~ 5.5 V
• Oscillator Type: Internal
• Operating Temperature: 0°C ~ 70°C
• Package / Case: 28-SOIC (7.5mm Width)
• Lead Free Status / RoHS Status: Contains lead / RoHS non-compliant
• Eeprom Size: -
• Data Converters: -

16.6 Keyboard Initialization
16.7 I/O Registers
MC68HC908JB16
Freescale Semiconductor
—
Rev. 1.1
When a keyboard interrupt pin is enabled, it takes time for the pullup
device 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:
These registers control and monitor operation of the keyboard module:
1. Mask keyboard interrupts by setting the IMASKK bit in the
2. Enable the KBI pins by setting the appropriate KBIEx bits in the
3. Write to the ACKK bit in the keyboard status and control register
4. Clear the IMASKK bit.
1. Configure the keyboard pins as outputs by setting the appropriate
2. Write logic 1s to the appropriate port A data register bits.
3. Enable the KBI pins by setting the appropriate KBIEx bits in the
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•
keyboard status and control register.
keyboard interrupt enable register.
to clear any false interrupts.
DDRA bits in data direction register A.
keyboard interrupt enable register.
Keyboard status and control register (KBSCR)
Keyboard interrupt enable register (KBIER)
Keyboard Interrupt Module (KBI)
Keyboard Interrupt Module (KBI)
Technical Data
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