Freescale Semiconductor, Inc.
Pinout and Signal Descriptions
Port Signals
3.6 Port Signals
The 68HC(9)12D60 incorporates eight ports which are used to control
and access the various device subsystems. When not used for these
purposes, port pins may be used for general-purpose I/O. In addition to
the pins described below, each port consists of a data register which can
be read and written at any time, and, with the exception of port AD0, port
AD1 (available only in 112TQFP), PE[1:0], RxCAN and TxCAN, a data
direction register which controls the direction of each pin. After reset all
general purpose I/O pins are configured as input.
3.6.1 Port A
Port A pins are used for address and data in expanded modes. In single
chip modes, the pins can be used as I/O. The port data register is not in
the address map during expanded and peripheral mode operation.
When it is in the map, port A can be read or written at anytime.
Register DDRA determines whether each port A pin is an input or output.
DDRA is not in the address map during expanded and peripheral mode
operation. Setting a bit in DDRA makes the corresponding bit in port A
an output; clearing a bit in DDRA makes the corresponding bit in port A
an input. The default reset state of DDRA is all zeros.
When the PUPA bit in the PUCR register is set, all port A input pins are
pulled-up internally by an active pull-up device. This bit has no effect if
the port is being used in expanded modes as the pull-ups are inactive.
Setting the RDPA bit in register RDRIV causes all port A outputs to have
reduced drive level. RDRIV can be written once after reset. RDRIV is not
in the address map in peripheral mode. Refer to Bus Control and
Input/Output.
68HC(9)12D60 — Rev 4.0
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