M68SDIL datasheet(54/460 Pages) MOTOROLA

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Pinout and Signal Descriptions

Technical Data

MC68HC912D60A — Rev 3.0

Pinout and Signal Descriptions

MOTOROLA

When the PUPB bit in the PUCR register is set, all port B 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 RDPB bit in register RDRIV causes all port B 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.

3.6.3 Port E

Port E pins operate differently from port A and B pins. Port E pins are

used for bus control signals and interrupt service request signals. When

a pin is not used for one of these specific functions, it can be used as

general-purpose I/O. However, two of the pins (PE[1:0]) can only be

used for input, and the states of these pins can be read in the port data

The PEAR register determines pin function, and register DDRE

determines whether each pin is an input or output when it is used for

general-purpose I/O. PEAR settings override DDRE settings. Because

PE[1:0] are input-only pins, only DDRE[7:2] have effect. Setting a bit in

the DDRE register makes the corresponding bit in port E an output;

clearing a bit in the DDRE register makes the corresponding bit in port E

an input. The default reset state of DDRE is all zeros.

When the PUPE bit in the PUCR register is set, PE7 and PE[3:0] are

pulled up by active devices.

Neither port E nor DDRE is in the map in peripheral mode; neither is in

the internal map in expanded modes with EME set.

Setting the RDPE bit in register RDRIV causes all port E 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.

Freescale Semiconductor, Inc.

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