Asynchronous Serial Interface (Uart) Mode - NEC UPD789026 Series User Manual

9.4.2 Asynchronous serial interface (UART) mode

In this mode, the one-byte data following the start bit is transmitted/received and thus full-duplex communication
is possible.
This device incorporates a UART-dedicated baud rate generator that enables communications at a desired
transfer rate from many options. In addition, the baud rate can also be defined by dividing the input clock to the
ASCK pin.
The UART-dedicated baud rate generator also can output the 31.25-kbps baud rate that complies with the MIDI
standard.
(1) Register setting
The UART mode is set by serial operation mode register 00 (CSIM00), asynchronous serial interface mode
register 00 (ASIM00), asynchronous serial interface status register 00 (ASIS00), and baud rate generator
control register 00 (BRGC00).
(a) Serial operation mode register 00 (CSIM00)
CSIM00 is set with a 1-bit or 8-bit memory manipulation instruction.
RESET input clears CSIM00 to 00H.
Set 00H to CSIM00 when UART mode is selected.
<7>
Symbol
CSIM00 CSIE00
CSIE00
0 Operation stop
1 Operation enable
DIR00
0 MSB
1 LSB
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CSCK00
0 Input clock to SCK0 pin from external
Dedicated baud rate generator output
1
Caution Be sure to set bit 0 and bits 3 to 6 to 0.
134
CHAPTER 9 SERIAL INTERFACE 00
6 5 4
0 0 0
Operation Control in 3-Wire Serial I/O Mode
Clock Selection in 3-Wire Serial I/O Mode
User's Manual U11919EJ3V0UM00
3 2 1
0 DIR00 CSCK00
Start Bit Specification
0 Address After Reset
0 FF72H 00H
R/W
R/W