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PIO-D144 User’s Manual
Version: 2.1 Date: 1999/10 Page 5
2.2 I/O Port Location
There are eighteen 8-bit I/O ports in the PIO-D144. Every I/O port can be
programmed as D/I or D/O port. When the PC is first power-on, all eighteen ports are
used as D/I port. The I/O port location is given as following:
Connector of PIO-D144
PA0 to PA7
PB0 to PB7
PC0 to PC7
CN1
CN1_PA
CN1_PB
CN1_PC
CN2
CN2_PA
CN2_PB
CN2_PC
CN3
CN3_PA
CN3_PB
CN3_PC
CN4
CN4_PA
CN4_PB
CN4_PC
CN5
CN5_PA
CN5_PB
CN5_PC
CN6
CN6_PA
CN6_PB
CN6_PC
Refer to Sec. 2.1 for board layout & I/O port location.
Note: PC0, PC1, PC2, PC3 of CN1 can be used as interrupt signal source. Refer
to Sec. 2.5 for more information.
2.3 Enable I/O Operation
When the PC is first power-on, all operation of D/I/O port are disable. The
enable/disable of D/I/O is controlled by the RESET\ signal. Refer to Sec. 3.3.1 for
more information about RESET\ signal. The power-on states are given as following:
•
All D/I/O operations are disable
•
All eighteen D/I/O ports are configured as D/I port
•
All D/O latch register are undefined.(refer to Sec. 2.4)
The user has to perform some initialization before using these D/I/O. The
recommended steps are given as following:
Step 1: Make sure which ports are D/O ports.
Step 2: Enable all D/I/O operation.(refer to Sec. 3.3.1).
Step 3: Select the active port (refer to Sec. 3.3.8).
Step 4: Send initial-value to the D/O latch register of this active port.
(Refer to Sec. 2.4 & Sec. 3.3.7)
Step 5: Repeat Step3 & Step4 for all D/O ports
Step 6: Configure all eighteen D/I/O ports to their expected D/I or D/O state.
(Refer to Sec. 3.3.9)
Refer to DEMO1.C for demo program.
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