NEC NEC PD78081(A), User Manual

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CHAPTER 11 SERIAL INTERFACE CHANNEL 2
(3) UART mode cautions
(a) In cases where bit 7 (TXE) of the asynchronous serial interface mode register (ASIM) has been cleared
and a transmit operation has been terminated during transmission, be sure to set 1 in TXE after setting
FFH in the transmit shift register (TXS) before executing the next transmission.
(b) In cases where bit 6 (RXE) of the asynchronous serial interface mode register (ASIM) has been cleared
(0) and a receive operation terminated during reception, enable/disable will differ depending on the timing,
the condition of the receive buffer register (RXB), and generation of the reception completed interrupt
request (INTSR) . The timing is displayed in Figure 11-11.
Figure 11-11 State of the Receive Buffer Register (RXB) when Reception is Interrupted, and Generation/
Non Generation of an Interrupt Request (INTSR)
When RXE is set to 0 at a time indicated by <1>, RXB holds the previous data and does not generate INTSR.
When RXE is set to 0 at a time indicated by <2>, RXB renews the data and does not generate INTSR.
When RXE is set to 0 at a time indicated by <3>, RXB renews the data and generates INTSR.
Parity RxD Pin
RXB
INTSR
<3> <1>
<2>