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Chapter 19 Port Integration Module (S12XFPIMV2)
MC9S12XF - Family Reference Manual, Rev.1.19
854
Freescale Semiconductor
19.3.11 Port E Data Register (PORTE)
19.3.12 Port E Data Direction Register (DDRE)
Address 0x0008 (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
PE7
PE6
PE5
PE4
PE3
PE2
PE1
PE0
W
Altern.
Function
XCLKS
or
ECLKX2
MODB
or
TAGHI
MODA
or
RE
or
TAGLO
ECLK
EROMCTL
or
LSTRB
or
LDS
RW
or
WE
IRQ
XIRQ
Reset
00000000
= Unimplemented or Reserved
Figure 19-9. Port E Data Register (PORTE)
Table 19-12. PORTE Register Field Descriptions
Field
Description
7-0
PE
Port E general purpose input/output data—Data Register
Port E bits 7 through 0 are associated with external bus control signals and interrupt inputs. These include mode
select (MODB, MODA), E clock, double frequency E clock, Instruction Tagging High and Low (TAGHI, TAGLO),
Read/Write (RW), Read Enable and Write Enable (RE, WE), Lower Data Select (LDS), IRQ, and XIRQ.
When not used with the alternative functions, Port E pins 7-2 can be used as general purpose I/O and pins 1-0 can
be used as general purpose inputs.
If the associated data direction bits of these pins are set to 1, a read returns the value of the port register, otherwise
the buffered pin input state is read.
Pins 6 and 5 are inputs with enabled pull-down devices while RESET pin is low.
Pins 7 and 3 are inputs with enabled pull-up devices while RESET pin is low.
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 19-10. Port E Data Direction Register (DDRE)