Chapter 2 Port Integration Module (S12XEP100PIMV1)
MC9S12XE-Family Reference Manual , Rev. 1.19
Freescale Semiconductor
127
NOTE
Due to internal synchronization circuits, it can take up to 2 bus clock cycles
until the correct value is read on PTS or PTIS registers, when changing the
DDRS register.
2.3.32
Port S Reduced Drive Register (RDRS)
Table 2-28. DDRS Register Field Descriptions
Field
Description
7-0
DDRS
Port S data direction
—
This register controls the data direction of pins 7 through 0.This register configures each Port S pin as either input
or output.
If SPI0 is enabled, the SPI0 determines the pin direction.
Refer to SPI section for details
.
If the associated SCI transmit or receive channel is enabled this register has no effect on the pins. The pin is forced
to be an output if a SCI transmit channel is enabled, it is forced to be an input if the SCI receive channel is enabled.
The data direction bits revert to controlling the I/O direction of a pin when the associated channel is disabled.
1 Associated pin is configured as output.
0 Associated pin is configured as input.
Address 0x024B
Access: User read/write
(1)
1. Read: Anytime.
Write: Anytime.
7
6
5
4
3
2
1
0
R
RDRS7
RDRS6
RDRS5
RDRS4
RDRS3
RDRS2
RDRS1
RDRS0
W
Reset
0
0
0
0
0
0
0
0
Figure 2-30. Port S Reduced Drive Register (RDRS)
Table 2-29. RDRS Register Field Descriptions
Field
Description
7-0
RDRS
Port S reduced drive
—Select reduced drive for outputs
This register configures the drive strength of output pins 7 through 0 as either full or reduced. If a pin is used as input
this bit has no effect.
1 Reduced drive selected (approx. 1/5 of the full drive strength).
0 Full drive strength enabled.
Because
of
an
order
from
the
United
States
International
Trade
Commission,
BGA-packaged
product
lines
and
part
numbers
indicated
here
currently
are
not
available
from
Freescale
for
import
or
sale
in
the
United
States
prior
to
September
2010:
S12XE
products
in
208
MAPBGA
packages