HD6473032F16 Datasheet, PDF (470/847 Pages) Renesas Technology Corp – Hardware Manual Renesas 16-Bit Single-Chip Microcomputer H8 Family/H8/300H Series

Section 13 Serial Communication Interface
13.2.3 Transmit Shift Register (TSR)
TSR is the register that transmits serial data.
Bit
7
6
5
4
3
2
1
0
Read/Write
—
—
—
—
—
—
—
—
The SCI loads transmit data from TDR into TSR, then transmits the data serially from the TxD
pin, LSB (bit 0) first. After transmitting one data byte, the SCI automatically loads the next
transmit data from TDR into TSR and starts transmitting it. If the TDRE flag is set to 1 in SSR,
however, the SCI does not load the TDR contents into TSR. The CPU cannot read or write TSR
directly.
13.2.4 Transmit Data Register (TDR)
TDR is an 8-bit register that stores data for serial transmission.
Bit
7
6
5
4
3
2
1
0
Initial value
Read/Write
1
1
1
1
1
1
1
1
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
When the SCI detects that TSR is empty, it moves transmit data written in TDR from TDR into
TSR and starts serial transmission. Continuous serial transmission is possible by writing the next
transmit data in TDR during serial transmission from TSR.
The CPU can always read and write TDR. TDR is initialized to H'FF by a reset and in standby
mode.
Rev. 3.00 Mar 21, 2006 page 440 of 814
REJ09B0302-0300