Motorola M68HC11EVBD, User Manual

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SUPPORT INFORMATION
M68HC11EVBU/D 6-3
Table 6-3. Battery Backup Connector (P3) Pin Assignments
Pin Number Signal Mnemonic Signal Name And Description
1 + +3 Vdc Power – Input voltage (+3.0 Vdc @ 25 µA) used by the
EVBU MC68HC68T1 real-time clock battery backup feature.
2
–
Ground
Table 6-4. MCU I/O Port Connectors (P4 and P5) Pin Assignments
Pin Number Signal Mnemonic Signal Name And Description
1 GND Ground
2 MODB /
VSTBY
MODE B – An input control line used in conjunction with the MODA
pin to select the MCU operating mode.
STANDBY VOLTAGE – An input MCU RAM standby power line.
3 MODA /
LIR*
MODE A – An input control line used in conjunction with the
MODB pin to select the MCU operating mode.
LOAD INSTRUCTION REGISTER – An open-drain output signal
used to indicate an instruction is starting.
4 STRA /
AS
STROBE A – An input edge detecting signal for parallel I/O device
handshaking in the single-chip mode of operation.
ADDRESS STROBE – An output control line used to demultiplex
port C address and data signals in the expanded multiplexed mode
of operation.
5 E ENABLE CLOCK
–
An output control line used for timing
reference. E clock frequency is one fourth the frequency of the
XTAL and EXTAL pins.
6 STRB /
R/W*
STROBE B
–
An output strobe signal for parallel I/O device
handshaking in the single-chip mode of operation.
READ/WRITE
–
An output control line used to control the direction
of transfers on the MCU external data bus in the expanded
multiplexed mode of operation.
7 EXTAL EXTERNAL CLOCK INPUT
–
An input clock signal used to control
the MCU internal clock generator. The frequency applied to this pin
must be four times higher than the desired E clock rate.