UPD784020 Datasheet, PDF (37/90 Pages) NEC – 16/8-BIT SINGLE-CHIP MICROCOMPUTER

mPD784020, 784021
8.8 SERIAL INTERFACE
Three independent serial interface channels are incorporated.
• Asynchronous serial interface (UART)/three-wire serial I/O (IOE) ¥ 2
• Synchronous serial interface (CSI) ¥ 1
• Three-wire serial I/O (IOE)
• Serial bus interface (SBI)
So, communication with points external to the system and local communication within the system can be performed
at the same time. (See Fig. 8-9.)
Fig. 8-9 Example Serial Interfaces
(a) UART + SBI
µ PD4711A
µ PD784021 (master)
RS-232-C
driver/
receiver
(UART)
RxD
TxD
Port
SB0
(SBI)
SCK0
µ PD4711A
RS-232-C
driver/
receiver
(UART)
RxD2
TxD2
Port
VDD
µPD75402A (slave)
SB0
SCK
µPD75328 (slave)
SB0
SCK
LCD
(b) UART + Three-wire serial I/O
µ PD4711A
RS-232-C
driver/
receiver
µ PD784021 (master)
µPD75108 (slave)
[Three-wire serial I/O]
(UART)
SO0
SI
RxD
SI0
SO
TxD
Port
SCK0
Note
INTPm
Port
SCK
Port
INT
SO1
SI1
SCK1
Note
INTPn
Port
µPD78014 (slave)
SI
SO
SCK
Port
INT
Note Handshake line
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