M68SDIL datasheet(49/460 Pages) MOTOROLA

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Pinout and Signal Descriptions

Signal Descriptions

MC68HC912D60A — Rev 3.0

Technical Data

MOTOROLA

Pinout and Signal Descriptions

3.5.9 Read/Write (R/W)

In all modes this pin can be used as general-purpose I/O and is an input

with an active pull-up out of reset. If the read/write function is required it

should be enabled by setting the RDWE bit in the PEAR register.

External writes will not be possible until enabled.

3.5.10 Low-Byte Strobe (LSTRB)

In all modes this pin can be used as general-purpose I/O and is an input

with an active pull-up out of reset. If the strobe function is required, it

should be enabled by setting the LSTRE bit in the PEAR register. This

signal is used in write operations and so external low byte writes will not

be possible until this function is enabled. This pin is also used as TAGLO

in Special Expanded modes and is multiplexed with the LSTRB function.

3.5.11 Instruction Queue Tracking Signals (IPIPE1 and IPIPE0)

These signals are used to track the state of the internal instruction

execution queue. Execution state is time-multiplexed on the two signals.

Refer to Development Support.

3.5.12 Data Bus Enable (DBE)

The DBE pin (PE7) is an active low signal that will be asserted low during

ECLK 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 ECLK 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. This pin has an active pull-up

during and after reset in single chip modes.

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