User's Manual U11919EJ3V0UM00
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CHAPTER 9 SERIAL INTERFACE 00
9.1 Serial Interface 00 Functions
Serial interface 00 employs the following three modes.
•
Operation stop mode
•
Asynchronous serial interface (UART) mode
•
3-wire serial I/O mode
(1)
Operation stop mode
This mode is used when serial transfer is not carried out. It enables power consumption reduction.
(2)
Asynchronous serial interface (UART) mode
In this mode, one byte of data following the start bit is transmitted/received, and full-duplex operation is
possible.
A UART-dedicated baud rate generator is incorporated, allowing communication over a wide range of baud
rates. In addition, the baud rate can be defined by scaling the input clock to the ASCK pin.
(3)
3-wire serial I/O mode (MSB/LSB start bit switchable)
In this mode, 8-bit data transfer is carried out with three lines, one for serial clock (SCK0) and two for serial
data (SI0, SO0).
The 3-wire serial I/O mode supports simultaneous transmit and receive operation, reducing data transfer
processing time.
It is possible to switch the start bit of 8-bit data to be transmitted between the MSB and the LSB, thus
allowing connection to devices with either start bit.
The 3-wire serial I/O mode is effective for connecting display controllers and peripheral I/Os such as the
75XL Series, 78K Series, and 17K Series, which have internal conventional synchronous serial interface.
9.2 Serial Interface 00 Configuration
Serial interface 00 has the following hardware configuration.
Table 9-1. Configuration of Serial Interface 00
Item
Configuration
Register
Transmission shift register 00 (TXS00)
Receive shift register 00 (RXS00)
Receive buffer register 00 (RXB00)
Control register
Serial operation mode register 00 (CSIM00)
Asynchronous serial interface mode register 00 (ASIM00)
Asynchronous serial interface status register 00 (ASIS00)
Baud rate generator control register 00 (BRGC00)
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