Datasheet

Chapter 3 Port Integration Module (PIM9E256V1) Block Description

MC9S12E256 Data Sheet, Rev. 1.10

Freescale Semiconductor 143

3.3.2.7 Port M Wired-OR Mode Register (WOMM)

Read: Anytime. Write: Anytime.

This register selects whether a port M output is configured as push-pull or wired-or. When a Wired-OR

Mode Register bit is set to 1, the corresponding output pin is driven active low only (open drain) and a

high level is not driven. A Wired-OR Mode Register bit has no effect if the corresponding pin is configured

as an input.

These bits apply also to the SCI2 outputs and allow a multipoint connection of several serial modules.

If the IIC is enabled, the associated pins are always set to wired-or mode, and the state of the WOMM[7:6]

bits have no effect. The WOMM[7:6] bits will not change to reflect their wired-or mode configuration

when the IIC is enabled.

Table 3-12. PPSM Field Descriptions

Field Description

7:3, 1:0

PPSM[7:3,

1:0]

Pull Select Port M

0 A pull-up device is connected to the associated port M pin.

1 A pull-down device is connected to the associated port M pin.

Module Base + 0x0016

76543210

WOMM7 WOMM6 WOMM5 WOMM4

0000

Reset 0 0 0 00000

= Reserved or Unimplemented

Figure 3-16. Port M Wired-OR Mode Register (WOMM)

Table 3-13. WOMM Field Descriptions

Field Description

7:4

WOMM[7:4]

Wired-OR Mode Port M

0 Output buffers operate as push-pull outputs.

1 Output buffers operate as open-drain outputs.