W921E840A Datasheet, PDF (23/58 Pages) Winbond – 4-BIT MICROCONTROLLER

W921E840A/W921C840
The serial interface configuration is shown below:
To Port P6 Normal I/O Register
P6.3 P6.2 P6.1 P6.0
Port P6 Pull-High Resisters
VDD
WDATA
WCLK
SRINV.3
RDATA
RCLK
P6IO.0
P6IO.1
SRINV.2
SCLK
P6IO.2
P6IO.3
Clock Source
and Latch
Control Circuit
Serial Clock Speed
Control Circuit
f SYS System
Clock
1/4
High Speed
Clock
SDATA
Serial/Parallel
I/O Buffer
P6PH
To Port P6
Serial Buffer
Registers
050H
14EH
The internal serial clock can be controlled by the serial clock speed control register (SRSPC); the
format is as follows:
SRSPC register: (address = 00BH, default data = 0H)
b3
b2
b1
b0
b3 b2 b1 b0
0000
0001
0010
0011
0100
0101
0110
0111
1000
1001
1010
Input frequency
Reserved
fsys/4 Hz
fsys/8 Hz
fsys/16 Hz
fsys/32 Hz
fsys/64 Hz
fsys/128 Hz
fsys/256 Hz
fsys/512 Hz
fsys/1024 Hz
fsys/2048 Hz
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Publication Release Date: July 1999
Revision A3