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

14.4.2 Asynchronous serial interface (UART) mode

In this mode, 1-byte data 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 0 (ASIM0)
• Asynchronous serial interface reception error status register 0 (ASIS0)
• Baud rate generator control register 0 (BRGC0)
• 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 BRGC0 register (see Figure 14-4).
<2> Set bits 1 to 4 (SL0, CL0, PS00, and PS01) of the ASIM0 register (see Figure 14-2).
<3> Set bit 7 (POWER0) of the ASIM0 register to 1.
<4> Set bit 6 (TXE0) of the ASIM0 register to 1. → Transmission is enabled.
Set bit 5 (RXE0) of the ASIM0 register to 1. → Reception is enabled.
<5> Write data to the TXS0 register. → Data transmission is started.
Caution Take relationship with the other party of communication when setting the port mode register
and port register.
The relationship between the register settings and pins is shown below.
Table 14-2. Relationship Between Register Settings and Pins
POWER0 TXE0 RXE0
0 0 0
336
CHAPTER 14 SERIAL INTERFACE UART0
PM10 P10 PM11
× × ×
Note Note Note
Preliminary User's Manual U17260EJ3V1UD
P11 UART0
Operation
TxD0/SCK10/P10
×
Pin Function
RxD0/SI10/P11