MC9S12XD256MAL Datasheet, PDF (939/1348 Pages) Freescale Semiconductor, Inc – Freescale’s Scalable Controller Area Network

23.0.5.35 Port M Polarity Select Register (PPSM)
R
W
Reset
7
PPSM7
0
6
PPSM6
5
PPSM5
4
PPSM4
3
PPSM3
2
PPSM2
0
0
0
0
0
Figure 23-37. Port M Polarity Select Register (PPSM)
1
PPSM1
0
0
PPSM0
0
Read: Anytime.
Write: Anytime.
This register selects whether a pull-down or a pull-up device is connected to the pin. If CAN is
active, a pull-up device can be activated on the related RXCAN inputs, but not a pull-down.
Table 23-36. PPSM Field Descriptions
Field
Description
7–0
PPSM[7:0]
Pull Select Port M
0 A pull-up device is connected to the associated port M pin, if enabled by the associated bit in register PERM
and if the port is used as general purpose or RXCAN input.
1 A pull-down device is connected to the associated port M pin, if enabled by the associated bit in register PERM
and if the port is used as a general purpose but not as RXCAN.
23.0.5.36 Port M Wired-OR Mode Register (WOMM)
R
W
Reset
7
WOMM7
0
6
WOMM6
5
WOMM5
4
WOMM4
3
WOMM3
2
WOMM2
1
WOMM1
0
0
0
0
0
0
Figure 23-38. Port M Wired-OR Mode Register (WOMM)
0
WOMM0
0
Read: Anytime.
Write: Anytime.
This register configures the output pins as wired-OR. If enabled the output is driven active low only
(open-drain). A logic level of “1” is not driven. It applies also to the CAN outputs and allows a
multipoint connection of several serial modules. This bit has no influence on pins used as inputs.
Table 23-37. WOMM Field Descriptions
Field
Description
7–0
Wired-OR Mode Port M
WOMM[7:0] 0 Output buffers operate as push-pull outputs.
1 Output buffers operate as open-drain outputs.