Datasheet

Chapter 2 Port Integration Module (S12XEPIMV1)
MC9S12XE-Family Reference Manual Rev. 1.25
Freescale Semiconductor 135
2.3.42 Port M Polarity Select Register (PPSM)
2.3.43 Port M Wired-Or Mode Register (WOMM)
Address 0x0255 Access: User read/write
(1)
1. Read: Anytime.
Write: Anytime.
76543210
R
PPSM7 PPSM6 PPSM5 PPSM4 PPSM3 PPSM2 PPSM1 PPSM0
W
Reset 00000000
Figure 2-40. Port M Polarity Select Register (PPSM)
Table 2-38. PPSM Register Field Descriptions
Field Description
7-0
PPSM
Port M pull device select—Determine pull device polarity on input pins
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 RXCAN[3:0] inputs, but not a pull-down.
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.
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.
Address 0x0256 Access: User read/write
(1)
1. Read: Anytime.
Write: Anytime.
76543210
R
WOMM7 WOMM6 WOMM5 WOMM4 WOMM3 WOMM2 WOMM1 WOMM0
W
Reset 00000000
Figure 2-41. Port M Wired-Or Mode Register (WOMM)
Table 2-39. WOMM Register Field Descriptions
Field Description
7-0
WOMM
Port M wired-or mode—Enable wired-or functionality
This register configures the output pins as wired-or independent of the function used on the pins. If enabled the
output is driven active low only (open-drain). A logic level of “1” is not driven.This allows a multipoint connection of
several serial modules. These bits have no influence on pins used as inputs.
1 Output buffers operate as open-drain outputs.
0 Output buffers operate as push-pull outputs.