MC68HC908LB8CPE Freescale Semiconductor, MC68HC908LB8CPE Datasheet - Page 88

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MC68HC908LB8CPE

Manufacturer Part Number
MC68HC908LB8CPE
Description
IC MCU 8K FLASH 8MHZ 20DIP
Manufacturer
Freescale Semiconductor
Series
HC08r
Datasheet

Specifications of MC68HC908LB8CPE

Core Processor
HC08
Core Size
8-Bit
Speed
8MHz
Peripherals
LVR, POR, PWM
Number Of I /o
18
Program Memory Size
8KB (8K x 8)
Program Memory Type
FLASH
Ram Size
128 x 8
Voltage - Supply (vcc/vdd)
4.5 V ~ 5.5 V
Data Converters
A/D 7x8b
Oscillator Type
Internal
Operating Temperature
-40°C ~ 85°C
Package / Case
20-DIP (0.300", 7.62mm)
Lead Free Status / RoHS Status
Lead free / RoHS Compliant
Eeprom Size
-
Connectivity
-

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Manufacturer
Quantity
Price
Part Number:
MC68HC908LB8CPE
Manufacturer:
IR
Quantity:
10
Keyboard Interrupt Module (KBI)
9.4 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:
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:
9.5 Low-Power Modes
The WAIT and STOP instructions put the microcontroller unit (MCU) in low power-consumption standby
modes.
9.5.1 Wait Mode
The keyboard module remains active in wait mode. Clearing the IMASKK bit in the keyboard status and
control register enables keyboard interrupt requests to bring the MCU out of wait mode.
9.5.2 Stop Mode
The keyboard module remains active in stop mode. Clearing the IMASKK bit in the keyboard status and
control register enables keyboard interrupt requests to bring the MCU out of stop mode.
9.6 Keyboard Module During Break Interrupts
The system integration module (SIM) controls whether the keyboard interrupt latch can be cleared during
the break state. The BCFE bit in the SIM break flag control register (SBFCR) enables software to clear
status bits during the break state.
To allow software to clear the keyboard interrupt latch during a break interrupt, write a 1 to the BCFE bit.
If a latch is cleared during the break state, it remains cleared when the MCU exits the break state.
To protect the latch during the break state, write a 0 to the BCFE bit. With BCFE at 0 (its default state),
writing to the keyboard acknowledge bit (ACKK) in the keyboard status and control register during the
break state has no effect. See
88
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.
1. Configure the keyboard pins as outputs by setting the appropriate DDRA bits in data direction
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 interrupt enable register.
register A.
9.7.1 Keyboard Status and Control
MC68HC908LB8 Data Sheet, Rev. 1
Register.
Freescale Semiconductor

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