NEC 78K0/KD1 Series User Manual page 248

(1) Receive buffer register 0 (RXB0)
This 8-bit register stores parallel data converted by receive shift register 0 (RXS0).
Each time 1 byte of data has been received, new receive data is transferred to this register from receive shift
register 0 (RXS0).
If the data length is set to 7 bits the receive data is transferred to bits 0 to 6 of RXB0 and the MSB of RXB0 is
always 0.
If an overrun error (OVE0) occurs, the receive data is not transferred to RXB0.
RESET input or POWER0 = 0 sets this register to FFH.
RXB0 can be read by an 8-bit memory manipulation instruction. No data can be written to this register.
(2) Receive shift register 0 (RXS0)
This register converts the serial data input to the R
RXS0 cannot be directly manipulated by a program.
(3) Transmit shift register 0 (TXS0)
This register is used to set transmit data. Transmission is started when data is written to TXS0, and serial data is
transmitted from the T
X
RESET input, POWER0 = 0, or TXE0 = 0 sets this register to FFH.
TXS0 can be written by an 8-bit memory manipulation instruction. This register cannot be read.
Caution Do not write the next transmit data to TXS0 before the transmission completion interrupt signal
(INTST0) is generated.
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CHAPTER 13 SERIAL INTERFACE UART0
D0 pins.
Preliminary User's Manual U16315EJ1V0UD
D0 pin into parallel data.
X