NEC PD78F9488 Manuale Utente

 

User’s Manual  U15331EJ4V1UD 

Serial interface 20 provides the following three modes. 
 
•  Operation stop mode 
•  Asynchronous serial interface (UART) mode 
•  3-wire serial I/O mode 
 

In operation stop mode, serial transfer is not executed, thereby reducing the power consumption.  The 

P20/SCK20/ASCK20, P21/SO20/TxD20, and P22/SI20/RxD20 pins can be used as normal I/O ports. 

 
(1) Register 

Operation stop mode is set by serial operation mode register 20 (CSIM20) and asynchronous serial interface 
mode register 20 (ASIM20). 
 
(a)  Serial operation mode register 20 (CSIM20) 

CSIM20 is set with a 1-bit or 8-bit memory manipulation instruction. 
RESET input clears CSIM20 to 00H. 

 

CSIE20

0

1

Operation control in 3-wire serial I/O mode

Operation disabled

Operation enabled

CSIE20

0

0

0

0

DIR20

CSCK20

0

CSIM20

<7>

6

5

4

Symbol

Address

After reset

R/W

FF72H

00H

R/W

3

2

1

0