Freescale Semiconductor, Inc.
Parallel Input/Output
Port B
When using the PB6/SDI pin, the following interactions must be noted:
1. If the SIOP function is required, then the SPE bit in the SCR must
be set. This causes the PB6/SDI pin buffer to be disabled to allow
the PB6/SDI pin to act as an input that feeds the serial data input
(SDI) of the SIOP. The pulldown device is disabled in this case.
2. If the SIOP function is in control of the PB6/SDI pin, the DDRB6
and PB6 data register bits are still accessible to the CPU and can
be altered or read without affecting the SIOP functionality.
However, if the DDRB6 bit is cleared, reading the PB6 data
register will return the current state of the PB6/SDI pin.
3. If the SIOP function is terminated by clearing the SPE bit in the
SCR, then the last conditions stored in the DDRB6, PDIB6, and
PB6 register bits will then control the PB6/SDI pin.
4. If the PB6/SDI pin is to be a digital input, then both the SPE bit in
the SCR and the DDRB6 bit must be cleared. Depending on the
external application, the pulldown device may also be disabled by
setting the PDIB6 pulldown inhibit bit.
5. If the PB6/SDI pin is to be a digital output, then the SPE bit in the
SCR must be cleared and the DDRB6 bit must be set. The
pulldown device will be disabled in this case.
MC68HC705JJ7/MC68HC705JP7 — Rev. 3.0
General Release Specification
Parallel Input/Output
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