Port B Data Register (Pbdat); Port B Data Direction Register (Pbdir) - Freescale Semiconductor MPC850 User Manual

34.3.1.2 Port B Data Register (PBDAT)

Reading the port B data register (PBDAT) returns data to the signal, regardless of whether
it is an input or output. This allows output conflicts to be found on the signal by comparing
the written data with the data on the signal. Data written to PBDAT is latched; if the
corresponding PBDIR bit is configured as an output, the latched value is driven onto its
respective signal. PBDAT can be read or written at any time and is not initialized.
Bits 0 1 2
Field
Reset
R/W
Addr
Bits 16 17 18
Field D16 D17 D18
Reset
R/W R/W R/W R/W
Addr
Table 34-8 describes PBDAT bits.
Bits Name
0–15, — Reserved
20–21
16–19, Dn Contains the data on the corresponding signal.
22–31

34.3.1.3 Port B Data Direction Register (PBDIR)

Port B data direction register (PBDIR) bits configure port B signals as general-purpose
inputs or outputs. If a signal is not programmed for general-purpose I/O, PBDIR selects the
peripheral function to be performed.
3 4 5 6
19 20 21 22
D19 D22
R/W R/W
Figure 34-8. Port B Data Register (PBDAT)
Table 34-8. PBDAT Bit Descriptions
Chapter 34. Parallel I/O Ports
7 8 9 10
—
Undefined
—
0xAC4
23 24 25 26
D23 D24 D25 D26
Undefined
R/W R/W R/W R/W
0xAC6
Description
Port B
11 12 13 14
27 28 29 30
D27 D28 D29 D30
R/W R/W R/W R/W
15
31
D31
R/W