How-To Guide

Table Of Contents
R01UH0823EJ0110 Rev.1.10 Page 979 of 1852
Nov 30, 2020
RX23W Group 33. Serial Communications Interface (SCIg, SCIh)
33.2.4 Transmit Data Register (TDR)
The TDR register is an 8-bit register that stores transmit data.
When the SCI detects that the TSR register is empty, it transfers the transmit data written in the TDR register to the TSR
register and starts transmission.
The double-buffered structures of the TDR register and the TSR register enable continuous serial transmission. If the
next transmit data has already been written to the TDR register when one frame of data is transmitted, the SCI transfers
the written data to the TSR register to continue transmission.
The CPU is able to read from or write to the TDR register at any time. Only write transmit data to the TDR register once
after each instance of the transmit data empty interrupt (TXI).
Address(es): SCI1.TDR 0008 A023h, SCI5.TDR 0008 A0A3h, SCI8.TDR 0008 A103h, SCI12.TDR 0008 B303h
b7 b6 b5 b4 b3 b2 b1 b0
Value after reset:
11111111