NEC 78K0 User Manual page 282

(c) Normal transmission
The T D6 pin outputs a high level when bit 7 (POWER6) of asynchronous serial interface operation mode
X
register 6 (ASIM6) is set to 1.
Transmission can be started by writing transmit data to transmit buffer register 6 (TXB6). The start bit, parity
bit, and stop bit are automatically appended to the data.
When transmission is started, the data in TXB6 is transferred to transmit shift register 6 (TXS6). After that,
the data is sequentially output from TXS6 to the T
stop bits set by ASIM6 are appended and a transmission completion interrupt request (INTST6) is generated.
Transmission is stopped until the data to be transmitted next is written to TXB6.
Figure 13-15 shows the timing of the transmission completion interrupt request (INTST6). This interrupt
occurs as soon as the last stop bit has been output.
Figure 13-15. Normal Transmission Completion Interrupt Request Timing
1. Stop bit length: 1
T D6 (output)
X
INTST6
2. Stop bit length: 2
T D6 (output)
X
INTST6
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CHAPTER 13 SERIAL INTERFACE UART6
If bit 6 (TXE6) of ASIM6 is then set to 1, transmission is enabled.
Start D0 D1 D2
Start D0 D1 D2
User's Manual U16227EJ2V0UD
D6 pin. When transmission is completed, the parity and
X
Parity
D6 D7
D6 D7 Parity
Stop
Stop