mc9s12e256 Freescale Semiconductor, Inc, mc9s12e256 Datasheet - Page 532

• Manufacturer Part Number: mc9s12e256
• Description: Hcs12 Microcontrollers 16-bit Microcontroller
• Manufacturer: Freescale Semiconductor, Inc

Chapter 18 Multiplexed External Bus Interface (MEBIV3)
18.3.2.16 Port K Data Direction Register (DDRK)
Read: Anytime
Write: Anytime
This register determines the primary direction for each port K pin configured as general-purpose I/O. This
register is not in the map in peripheral or expanded modes while the EMK control bit in MODE register is
set. Therefore, these accesses will be echoed externally.
532
DDRK
Field
7:0
Reset
W
R
Data Direction Port K Bits
0 Associated pin is a high-impedance input
1 Associated pin is an output
Note: It is unwise to write PORTK and DDRK as a word access. If you are changing port K pins from inputs to
Note: To ensure that you read the correct value from the PORTK pins, always wait at least one cycle after writing
Bit 7
0
7
outputs, the data may have extra transitions during the write. It is best to initialize PORTK before enabling
as outputs.
to the DDRK register before reading from the PORTK register.
Figure 18-21. Port K Data Direction Register (DDRK)
6
0
6
Table 18-14. DDRK Field Descriptions
MC9S12E256 Data Sheet, Rev. 1.08
5
0
5
4
0
4
Description
3
3
0
2
2
0
Freescale Semiconductor
1
0
1
Bit 0
0
0