General Purpose I/O Module
MCF5272 ColdFire Integrated Microprocessor User’s Manual, Rev. 3
17-10
Freescale Semiconductor
17.3
Data Direction Registers
These registers are used to program GPIO port signals as inputs or outputs. The data direction bit for any
line is ignored unless that line is configured for general purpose I/O in the appropriate control register. If
a GPIO line changes from an input to an output, the initial data on that pin is the last data written to the
latch by the corresponding data register.
At system reset, these register bits are all cleared, configuring all port I/O lines as general purpose inputs.
Bootstrap software must write an appropriate value into the data direction register to configure GPIO port
signals as outputs. When these registers are first written, any internal pullups on the corresponding I/O pins
are disabled.
A detailed description is provided only for data direction register A (PADDR). The control bits in all three
registers operate in the same manner.
17.3.1
Port A Data Direction Register (PADDR)
The PADDR determines the signal direction of each parallel port pin programmed as a GPIO port in the
PACNT.
17.3.2
Port B Data Direction Register (PBDDR)
The PBDDR determines the signal direction of each parallel port pin programmed as a GPIO port in the
PBCNT.
15
0
Field
PADDR
Reset
0000_0000_0000_0000
R/W
Read/Write
Addr
MBAR + 0x0084
Figure 17-4. Port A Data Direction Register (PADDR)
Table 17-9. PADDR Field Descriptions
Bits
Name
Description
15–0
PADDR
Data direction bits. Each data direction bit selects the direction of the signal as follows:
0 Signal is defined as an input.
1 Signal is defined as an output.
15
0
Field
PBDDR
Reset
0000_0000_0000_0000
R/W
Read/Write
Addr
MBAR + 0x008C
Figure 17-5. Port B Data Direction Register (PBDDR)