Asynchronous Serial Interface (Uart) Mode - NEC mPD780024AS Series Preliminary User's Manual

13.4.2 Asynchronous serial interface (UART) mode

This mode enables full-duplex operation wherein one byte of data after the start bit is transmitted or received.
The on-chip baud rate generator dedicated to UART enables communications using a wide range of selectable
baud rates.
The UART baud rate generator can also be used to generate a MIDI-standard baud rate (31.25 kbps).
(1) Register settings
UART mode settings are performed by the asynchronous serial interface mode register 0 (ASIM0), asynchronous
serial interface status register 0 (ASIS0), and the baud rate generator control register 0 (BRGC0).
(a) Asynchronous serial interface mode register 0 (ASIM0)
ASIM0 is set by a 1-bit or 8-bit memory manipulation instruction.
RESET input sets ASIM0 to 00H.
Caution In UART mode, set the port mode register (PMXX) as follows. Set the output latch of the
port set to output mode (PMXX = 0) to 0.
• During receive operation
Set P23 (RXD0) to input mode (PM23 = 1)
• During transmit operation
Set P24 (TXD0) to output mode (PM24 = 0)
• During transmit/receive operation
Set P23 to input mode, and P24 to output mode
CHAPTER 13 SERIAL INTERFACE (UART0)
Preliminary User's Manual U16035EJ1V0UM
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