MC68HC12 Datasheet, PDF (53/478 Pages) Motorola, Inc – The MC68HC912DT128A microcontroller unit (MCU) is a 16-bit device composed of standard on-chip peripherals including a 16-bit central processing unit

Pinout and Signal Descriptions
Signal Descriptions
3.4.11 Instruction Queue Tracking Signals (IPIPE1 and IPIPE0)
IPIPE1 (PE6) and IPIPE0 (PE5) signals are used to track the state of the
internal instruction queue. Data movement and execution state
information is time-multiplexed on the two signals. Refer to Development
Support.
3.4.12 Data Bus Enable (DBE)
The DBE pin (PE7) is an active low signal that will be asserted low during
E-clock high time. DBE provides separation between output of a
multiplexed address and the input of data. When an external address is
stretched, DBE is asserted during what would be the last quarter cycle
of the last E-clock cycle of stretch. In expanded modes this pin is used
to enable the drive control of external buses during external reads. Use
of the DBE is controlled by the NDBE bit in the PEAR register. DBE is
enabled out of reset in expanded modes.
3.4.13 Inverted E clock (ECLK)
The ECLK pin (PE7) can be used to latch the address for de-
multiplexing. It has the same behavior as the ECLK, except is inverted.
In expanded modes this pin is used to enable the drive control of external
buses during external reads. Use of the ECLK is controlled by the NDBE
and DBENE bits in the PEAR register.
3.4.14 Calibration reference (CAL)
The CAL pin (PE7) is the output of the Slow Mode programmable clock
divider, SLWCLK, and is used as a calibration reference. The SLWCLK
frequency is equal to the crystal frequency out of reset and always has
a 50% duty. If the DBE function is enabled it will override the enabled
CAL output. The CAL pin output is disabled by clearing CALE bit in the
PEAR register.
MC68HC912DT128A — Rev 4.0
MOTOROLA
Pinout and Signal Descriptions
Technical Data
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