HD64F3039F18 Datasheet, PDF (361/710 Pages) Renesas Technology Corp – Renesas 16-Bit Single-Chip Microcomputer H8 Family / H8/300H Series

Section 11 Serial Communication Interface
11.2.3 Transmit Shift Register (TSR)
TSR is an 8-bit register used to transmit 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.
11.2.4 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. 26, 2007 Page 337 of 682
REJ09B0353-0300