mc9s12xd256 Freescale Semiconductor, Inc, mc9s12xd256 Datasheet - Page 832

• Manufacturer Part Number: mc9s12xd256
• Description: Hcs12x Microcontrollers
• Manufacturer: Freescale Semiconductor, Inc

Chapter 22 DP512 Port Integration Module (S12XDP512PIMV2)
22.3.2.9
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.
832
These registers are reset to zero. Two bus clock cycles after reset release the register values are updated with the associated
pin values.
PE[7:0]
Reset
Func.
Field
7–0
Alt.
W
R
ECLKX2
XCLKS
Port E — Port E bits 7–0 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 (R/W), Read Enable and Write Enable (RE, WE), Lower Data Select (LDS), IRQ, and XIRQ.
When not used for any of these specific 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 data direction bits of the associated I/O pins are set to logic level “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.
PE7
Port E Data Register (PORTE)
or
0
7
= Unimplemented or Reserved
MODB
TAGHI
PE6
or
0
6
Figure 22-11. Port E Data Register (PORTE)
Table 22-12. PORTE Field Descriptions
TAGLO
MC9S12XDP512 Data Sheet, Rev. 2.17
MODA
PE5
RE
or
or
0
5
ECLK
PE4
0
4
Description
EROMCTL
LSTRB
PE3
LDS
or
or
0
3
PE2
R/W
WE
or
0
2
Freescale Semiconductor
PE1
IRQ
—
1
1
XIRQ
PE0
—
0
1