mc68hc912bc32 Freescale Semiconductor, Inc, mc68hc912bc32 Datasheet - Page 209

• Manufacturer Part Number: mc68hc912bc32
• Description: M68hc12 Microcontrollers
• Manufacturer: Freescale Semiconductor, Inc

DDS0 — Data Direction for Port S Bit 0
DDS1 — Data Direction for Port S Bit 1
DDS2 and DDS3 — Data Direction for Port S Bit 2 and Bit 3
DDS6–DDS4 — Data Direction for Port S Bits 6–4
DDS7 — Data Direction for Port S Bit 7
14.4.3 Pullup and Reduced Drive Register for Port S
Read: Anytime
Write: Anytime
RDPS2 — Reduce Drive of PS7–PS4
RDPS1 — Reduce Drive of PS3 and PS2
RDPS0 — Reduce Drive of PS1 and PS0
PUPS2 — Pullup Port S Enable PS7–PS4
Freescale Semiconductor
If the SCI receiver is configured for 2-wire SCI operation, corresponding port S pins are input
regardless of the state of these bits.
If the SCI transmitter is configured for 2-wire SCI operation, corresponding port S pins are output
regardless of the state of these bits.
These bits are for general-purpose only.
If the SPI is enabled and expects the corresponding port S pin to be an input, it will be an input
regardless of the state of the DDRS bit. If the SPI is enabled and expects the bit to be an output, it will
be an output only if the DDRS bit is set.
In SPI slave mode, DDS7 has no meaning or effect; the PS7 pin is dedicated as the SS input. In SPI
master mode, DDS7 determines whether PS7 is an error detect input to the SPI or a general-purpose
or slave select output line.
0 = Port S output drivers for bits 7–4 operate normally.
1 = Port S output pins for bits 7–4 have reduced drive capability for lower power and less noise.
0 = Port S output drivers for bits 3 and 2 operate normally.
1 = Port S output pins for bits 3 and 2 have reduced drive capability for lower power and less noise.
0 = Port S output drivers for bits 1 and 0 operate normally.
1 = Port S output pins for bits 1 and 0 have reduced drive capability for lower power and less noise.
0 = No internal pullups on port S bits 7–4.
1 = Port S input pins for bits 7–4 have an active pullup device. If a pin is programmed as output, the
pullup device becomes inactive.
Address:
Reset:
Read:
Figure 14-22. Pullup and Reduced Drive Register for Port S (PURDS)
Write:
$00DB
Bit 7
0
0
= Unimplemented
RDPS2
6
0
M68HC12B Family Data Sheet, Rev. 9.1
RDPS1
5
0
RDPS0
4
0
3
0
0
PUPS2
2
0
PUPS1
1
0
PUPS0
Bit 0
0
Port S
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