Datasheet

Pinout and Signal Description
Signal Descriptions
MC9S12DP256 — Revision 1.1
Pinout and Signal Description
MCU will recognize another interrupt as soon as the interrupt mask bit in
the MCU is cleared (normally upon return from an interrupt).
Mode Select
(MODA, MODB,
and MODC)
The state of these pins during reset determine the MCU operating mode.
After reset, MODA and MODB can be configured as instruction queue
tracking signals IPIPE0 and IPIPE1 in expanded modes. MODA, and
MODB have active pulldowns during reset. MODC has the pull-up on the
pin enabled after reset.
Single-Wire
Background Mode
Pin (BKGD) shared
with MODC
The BKGD pin receives and transmits serial background debugging
commands. A special self-timing protocol is used.Out of reset the pin is
configured as input with internal pull-up enabled.
NOTE: The resistance of the internal pull-up may be too high depending on the
speed and the load to ensure proper BDM communication. In this case
an additional external pull-up resistor must be provided.
External Address
and Data Buses
(ADDR[15:0] and
DATA[15:0])
External bus pins share functions with general-purpose I/O ports A and
B. In single-chip operating modes, the pins can be used for
general-purpose I/O; in expanded modes, the pins are used for the
external buses.
In expanded wide mode, ports A and B are used for multiplexed 16-bit
data and address buses. PA[7:0] correspond to
ADDR[15:8]/DATA[15:8]; PB[7:0] correspond to ADDR[7:0]/DATA[7:0].
In expanded narrow mode, ports A and B are used for the16-bit address
bus, and an 8-bit data bus is multiplexed with the most significant half of
the address bus on port A. In this mode, 16-bit data is handled as two
back-to-back bus cycles, one for the high byte followed by one for the
low byte. PA[7:0] correspond to ADDR[15:8] and to DATA[15:8] or
DATA[7:0], depending on the bus cycle. The state of the address pins
should be latched at the rising edge of E. To allow for maximum address
setup time at external devices, a transparent latch should be used.
Freescale Semiconductor, I
Freescale Semiconductor, Inc.
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