227
Serial Control Register 3 (SCR3)
Bit
7
6
5
4
3
2
1
0
TIE
RIE
TE
RE
MPIE
TEIE
CKE1
CKE0
Initial value
0
0
0
0
0
0
0
0
Read/Write
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
Serial control register 3 (SCR3) is an 8-bit register that controls SCI3 transmit and receive
operations, enables or disables serial clock output in asynchronous mode, enables or disables
interrupts, and selects the serial clock source. SCR3 can be read and written by the CPU at any
time.
SCR3 is initialized to H'00 upon reset or in standby mode, watch mode, subactive mode, or
subsleep mode.
Bit 7—Transmit Interrupt Enable (TIE): Bit 7 enables or disables the transmit data empty
interrupt request (TXI) when data is transferred from TDR to TSR and the transmit data register
empty bit (TDRE) in the serial status register (SSR) is set to 1. The TXI interrupt can be cleared
by clearing bit TDRE to 0, or by clearing 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 enables or disables the receive error interrupt
request (ERI), and the receive data full interrupt request (RXI) when data is transferred from RSR
to RDR and the receive data register full bit (RDRF) in the serial status register (SSR) is set to 1.
Receive errors include overrun errors, framing errors, and parity errors. RXI and ERI interrupts
can be cleared by clearing SSR flag RDRF, or flags FER, PER, and OER to 0, or by clearing bit
RIE to 0.
Bit 6: RIE
Description
0
Receive data full interrupt request (RXI) and receive error interrupt request
(ERI) disabled
(initial value)
1
Receive data full interrupt request (RXI) and receive error interrupt request
(ERI) enabled