W921E840A Datasheet, PDF (19/58 Pages) Winbond – 4-BIT MICROCONTROLLER

W921E840A/W921C840
• P6.0 to P6.3: Multi-function I/O pins (selected by P6IO register)
− Normal function I/O pins
− Special function I/O pins
P6IO register: (address = 012H, default data = 0H)
b3
b2
b1
b0
0: Normal I/O P6.0
1: Work as the data output pin of the WCLK pin
(WDATA)
0: Normal I/O P6.1
1: Work as the clock I/O pin of the WDATA pin
(WCLK)
0: Normal I/O P6.2
1: Work as the data input pin of the RCLK pin
(RDATA)
0: Normal I/O P6.3
1: Work as the clock I/O pin of the RDATA pin
(RCLK)
• PA.0 to PA.3: Normal function I/O pins only
• PB.0 to PB.3: Normal function I/O pins only
• PC.1 to PC.3: Normal function I/O pins only
• PD.0 to PD.1: Normal function I/O pins only
6.5.2 Pull High and Open Drain Control of I/O
Some of the above I/O ports can be controlled with pull-high resistor or open drain by programming
the special register.
All pull-high resistors of the following descriptions are 400KΩ under 3.0 voltage test condition. After
power-on reset the following special register will all reset to 0H.
• P4.0 to P4.3:
P4PH register: (address = 003H, default data = 0H)
b3
b2
b1
b0
0: P4.0 without pull-high resistor
1: P4.0 with pull-high resistor
0: P4.1 without pull-high resistor
1: P4.1 with pull-high resistor
0: P4.2 without pull-high resistor
1: P4.2 with pull-high resistor
0: P4.3 without pull-high resistor
1: P4.3 with pull-high resistor
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Publication Release Date: July 1999
Revision A3