UPD784907 Datasheet, PDF (45/98 Pages) NEC – 16-BIT SINGLE-CHIP MICROCONTROLLER

µPD784907, 784908
8.8.1 Asynchronous serial interface/3-wire serial I/O (UART/IOE)
Two serial interface channels, from which asynchronous serial interface mode and 3-wire serial I/O mode can be
selected, are provided.
(1) Asynchronous serial interface mode
In this mode, 1-byte data is transferred or received after a start bit.
A baud rate generator is incorporated to enable communication at a wide range of baud rates.
A baud rate can be defined by dividing the frequency of a clock signal input to the ASCK pin.
By using the baud rate generator, a baud rate conforming to the MIDI standard (31.25 kbps) can be obtained.
Figure 8-11. Block Diagram of Asynchronous Serial Interface Mode
Internal bus
Receive buffer RXB, RXB2
RxD, RxD2
TxD, TxD2
Baud rate generator
fXX
ASCK, ASCK2
Receive
shift register
Transmission
shift register
TXS, TXS2
Reception
control parity
check
INTSR,
INTSR2
INTSER,
INTSER2
Transmission
control parity
bit addition
INTST, INTST2
1/2 ⁿ⁺¹
1/2m
1/2m
Remark
fXX: Oscillating frequency or external clock input frequency
n = 0 to 11
m = 16 to 30
Data Sheet U11680EJ2V0DS00
45