UPD784218 Datasheet, PDF (40/92 Pages) NEC – 16-/8-BIT SINGLE-CHIP MICROCONTROLLERS

µPD784218, 784218Y
8.7.1 Asynchronous serial interface/3-wire serial I/O (UART/IOE)
Two channels of serial interfaces for which an asynchronous serial interface mode and 3-wire serial I/O mode
can be selected are provided.
(1) Asynchronous serial interface mode
In this mode, data of 1 byte following the start bit is transmitted or received.
Because an on-chip baud rate generator is provided, a wide range of baud rates can be set.
Moreover, the clock input to the ASCK pin can be divided to define a baud rate.
When the baud rate generator is used, a baud rate conforming to the MIDI standard (31.25 kbps) can also
be obtained.
Figure 8-10. Block Diagram When in Asynchronous Serial Interface Mode
RxD1, RxD2
TxD1, TxD2
Internal bus
8
Receive buffer register
1, 2 (RXB1, RXB2)
8
8
Receive shift register
1, 2 (RX1, RX2)
Transmit shift register
1, 2 (TXS1, TXS2)
Receive control
Baud rate generator ^{parity check}
INTSR1, Transmit control
INTSR2 parity added
INTST1,
INTST2
ASCK1, ASCK2
5-bit counter × 2
transmit/receive clock generation
Selector
fXX to fXX/2⁵
40
Data Sheet U12304EJ2V0DS00