Asynchronous Serial Interface (Uart) Mode - NEC 78K0 User Manual

13.4.2 Asynchronous serial interface (UART) mode

In this mode, data of 1 byte is transmitted/received following a start bit, and a full-duplex operation can be
performed.
A dedicated UART baud rate generator is incorporated, so that communication can be executed at a wide range of
baud rates.
(1) Registers used
• Asynchronous serial interface operation mode register 6 (ASIM6)
• Asynchronous serial interface reception error status register 6 (ASIS6)
• Asynchronous serial interface transmission status register 6 (ASIF6)
• Clock selection register 6 (CKSR6)
• Baud rate generator control register 6 (BRGC6)
• Asynchronous serial interface control register 6 (ASICL6)
• Input switch control register (ISC)
• Port mode register 1 (PM1)
• Port register 1 (P1)
The basic procedure of setting an operation in the UART mode is as follows.
<1> Set the CKSR6 register (see Figure 13-8).
<2> Set the BRGC6 register (see Figure 13-9).
<3> Set bits 0 to 4 (ISRM6, SL6, CL6, PS60, PS61) of the ASIM6 register (see Figure 13-5).
<4> Set bits 0 and 1 (TXDLV6, DIR6) of the ASICL6 register (see Figure 13-10).
<5> Set bit 7 (POWER6) of the ASIM6 register to 1.
<6> Set bit 6 (TXE6) of the ASIM6 register to 1. → Transmission is enabled.
Set bit 5 (RXE6) of the ASIM6 register to 1. → Reception is enabled.
<7> Write data to transmit buffer register 6 (TXB6). → Data transmission is started.
Caution Take relationship with the other party of communication when setting the port mode register
and port register.
CHAPTER 13 SERIAL INTERFACE UART6
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