S912XEG128J2MAA Datasheet, PDF (113/1324 Pages) Freescale Semiconductor, Inc – Microcontrollers

2.3.11 Port E Data Register (PORTE)
Chapter 2 Port Integration Module (S12XEPIMV1)
Address 0x0008 (PRR)
Access: User read/write⁽¹⁾
7
R
PE7
W
6
PE6
5
PE5
4
PE4
3
PE3
2
PE2
1
PE1
0
PE0
Altern.
Function
XCLKS
or
ECLKX2
MODB
or
TAGHI
MODA
or
RE
or
TAGLO
EROMCTL
or
RW
ECLK
LSTRB
or
or
WE
LDS
IRQ
XIRQ
Reset
0
0
0
0
0
0
—⁽²⁾
—²
= Unimplemented or Reserved
Figure 2-9. Port E Data Register (PORTE)
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.
2. These registers are reset to zero. Two bus clock cycles after reset release the register values are updated with the associated
pin values.
Field
7-2
PE
1
PE
0
PE
Table 2-12. PORTE Register Field Descriptions
Description
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).
When not used with the alternative functions, Port E pins 7-2 can be used as general purpose I/O.
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.
Port E general purpose input data and interrupt—Data Register, IRQ input.
This pin can be used as general purpose and IRQ input.
Port E general purpose input data and interrupt—Data Register, XIRQ input.
This pin can be used as general purpose and XIRQ input.
MC9S12XE-Family Reference Manual Rev. 1.25
Freescale Semiconductor
113