3 transmit shift register (sctsr), 4 transmit fifo data register (scftdr) – Renesas SH7781 User Manual
Page 1077
21. Serial Communication Interface with FIFO (SCIF)
Rev.1.00 Jan. 10, 2008 Page 1047 of 1658
REJ09B0261-0100
21.3.3
Transmit Shift Register (SCTSR)
SCTSR is a register used to transmit serial data.
To perform serial data transmission, the SCIF first transfers transmit data from SCFTDR to
SCTSR, then sends the data to the TXD pin starting with the LSB (bit 0). When transmission of
one byte of serial data is completed, the next transmit data is automatically transferred from
SCFTDR to SCTSR, and transmission started.
SCTSR cannot be directly read from and written to by the CPU.
0
1
2
3
4
5
6
7
⎯
⎯
⎯
⎯
⎯
⎯
⎯
⎯
⎯
⎯
⎯
⎯
⎯
⎯
⎯
⎯
BIt:
Initial value:
R/W:
21.3.4
Transmit FIFO Data Register (SCFTDR)
SCFTDR is an 8-bit FIFO register of 64 stages that stores data for serial transmission.
If SCTSR is empty when transmit data has been written to SCFTDR, the SCIF transfers the
transmit data written in SCFTDR to SCTSR and starts serial transmission.
SCFTDR is a write-only register, and cannot be read from by the CPU. The next data cannot be
written when SCFTDR is filled with 64 bytes of transmit data. Data written in this case is ignored.
0
1
2
3
4
5
6
7
—
—
—
—
—
—
—
—
W
W
W
W
W
W
W
W
BIt:
Initial value:
R/W: