10.2.6 Serial control register 3 (SCR3)
SCR3 is an 8-bit register for selecting transmit or receive operation, the asynchronous mode clock
output, interrupt request enabling or disabling, and the transmit/receive clock source.
SCR3 can be read or written by the CPU at any time.
SCR3 is initialized to H'00 upon reset, and in standby, module standby or watch mode.
Bit 7: Transmit interrupt enable (TIE)
Bit 7 selects enabling or disabling of the transmit data empty interrupt request (TXI) when transmit
data is transferred from the transmit data register (TDR) to the transmit shift register (TSR), and bit
TDRE in the serial status register (SSR) is set to 1.
TXI can be released by clearing bit TDRE or bit TIE to 0.
Bit 7
TIE
Description
0
Transmit data empty interrupt request (TXI) disabled
(initial value)
1
Transmit data empty interrupt request (TXI) enabled
Bit 6: Receive interrupt enable (RIE)
Bit 6 selects enabling or disabling of the receive data full interrupt request (RXI) and the receive
error interrupt request (ERI) when receive data is transferred from the receive shift register (RSR) to
the receive data register (RDR), and bit RDRF in the serial status register (SSR) is set to 1. There
are three kinds of receive error: overrun, framing, and parity.
RXI can be released by clearing bit RDRF or the FER, PER, or OER error flag to 0, or by clearing
bit RIE to 0.
Bit 6
RIE
Description
0
Receive data full interrupt request (RXI) and receive error interrupt
(initial value)
request (ERI) disabled
1
Receive data full interrupt request (RXI) and receive error interrupt
request (ERI) enabled
Bit
Initial value
Read/Write
7
TIE
0
R/W
6
RIE
0
R/W
5
TE
0
R/W
4
RE
0
R/W
3
MPIE
0
R/W
0
CKE0
0
R/W
2
TEIE
0
R/W
1
CKE1
0
R/W
257