W741E20X Datasheet, PDF (16/84 Pages) Winbond – 4-BIT FLASH MICROCONTROLLER

Preliminary W741E20X
Bit 0 = 0 RB.0 works as output pin; Bit 0 = 1 RB.0 works as input pin
Bit 1 = 0 RB.1 works as output pin; Bit 1 = 1 RB.1 works as input pin
Bit 2 = 0 RB.2 works as output pin; Bit 2 = 1 RB.2 works as input pin
Bit 3 = 0 RB.3 works as output pin; Bit 3 = 1 RB.3 works as input pin
At initial reset, the port RB is input mode (PM2 = 1111B).
Port Mode 3 Register (PM3)
Port Mode 3 Register is organized as a 4-bit binary register (PM3.0 to PM3.3). PM3 can be used to
determine the operating mode of the output port RE and the clock rate of the serial I/O function. The
PM3 control diagram is shown in Figure 8. The bit descriptions are as follows:
3210
PM3 W
W
Note: W means write only.
Bit 0 is reserved.
Bit 1 = 0 The output of the port RE is the output of the internal parallel port RT.
= 1 The port RE works as the serial input/output port.
Bit 2 is reserved.
Bit 3 = 0 Serial Tx rate = Fosc/2
= 1 Serial Tx rate = Fosc/256
Internal parallel port RT
Fosc/256
Fosc/2
PM3.3
Serial I/O port
MUX.
PM3.1
Port RE
Figure 8. PM3 Control Diagram
Port Mode 4 Register (PM4)
The port mode 4 register is organized as 4-bit binary register (PM4.0 to PM4.3). PM4 can be used to
control the input/output mode of port RC. PM4 is controlled by the MOV PM4, #I instruction. The bit
descriptions are as follows:
3 210
PM4 w w w w
Note: W means write only.
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