Datasheet

Chapter 2 Port Integration Module (S12XEPIMV1)
MC9S12XE-Family Reference Manual Rev. 1.25
114 Freescale Semiconductor
2.3.12 Port E Data Direction Register (DDRE)
2.3.13 S12X_EBI ports, BKGD pin Pull-up Control Register (PUCR)
Address 0x0009 (PRR) Access: User read/write
(1)
1. Read: Anytime. In emulation modes, read operations will return the data from the external bus, in all other modes the data source
is depending on the data direction value.
Write: Anytime. In emulation modes, write operations will also be directed to the external bus.
76543210
R
DDRE7 DDRE6 DDRE5 DDRE4 DDRE3 DDRE2
00
W
Reset 00000000
= Unimplemented or Reserved
Figure 2-10. Port E Data Direction Register (DDRE)
Table 2-13. DDRE Register Field Descriptions
Field Description
7-2
DDRE
Port E Data Direction—
This register controls the data direction of pins 7 through 2.
The external bus function controls the data direction for the associated pins. In this case the data direction bits will
not change.
When operating a pin as a general purpose I/O, the associated data direction bit determines whether it is an input
or output.
1 Associated pin is configured as output.
0 Associated pin is configured as high-impedance input.
1-0 Reserved—
Port E bit 1 (associated with
IRQ) and bit 0 (associated with XIRQ) cannot be configured as outputs. Port E, bits 1
and 0, can be read regardless of whether the alternate interrupt function is enabled.
Address 0x000C (PRR) Access: User read/write
(1)
1. Read:Anytime in single-chip modes.
Write:Anytime, except BKPUE which is writable in Special Test Mode only.
76543210
R
PUPKE BKPUE
0
PUPEE PUPDE PUPCE PUPBE PUPAE
W
Reset 11010000
= Unimplemented or Reserved
Figure 2-11. S12X_EBI ports, BKGD pin Pull-up Control Register (PUCR)