NEC 78K0 Series User Manual page 368

(c) Normal transmission
When bit 7 (POWER6) of asynchronous serial interface operation mode register 6 (ASIM6) is set to 1 and bit
6 (TXE6) of ASIM6 is then set to 1, transmission is enabled. 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 transmit data is sequentially output from TXS6 to the T
parity and 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 15-15 shows the timing of the transmission completion interrupt request (INTST6). This interrupt
occurs as soon as the last stop bit has been output.
Figure 15-15. 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
368
CHAPTER 15 SERIAL INTERFACE UART6
Start D0 D1 D2
Start D0 D1 D2
Preliminary User's Manual U17260EJ3V1UD
D6 pin. When transmission is completed, the
X
Parity
D6 D7 Stop
D6 D7 Parity Stop