How-To Guide

Table Of Contents
R01UH0823EJ0110 Rev.1.10 Page 978 of 1852
Nov 30, 2020
RX23W Group 33. Serial Communications Interface (SCIg, SCIh)
33.2.3 Receive Data Register H, L, HL (RDRH, RDRL, RDRHL)
Receive Data Register H (RDRH)
Receive Data Register L (RDRL)
Receive Data Register HL (RDRHL)
The RDRH and RDRL registers are 8-bit registers that store receive data. Use these registers when asynchronous mode
and 9-bit data length are selected.
The RDRL register is the shadow register of the RDR register; i.e. access to the RDRL register is equivalent to access to
the RDR register.
After one frame of data is received, the received data is transferred from the RSR register to these registers, thus allowing
the RSR register to receive the next data.
The RSR, RDRH and RDRL registers have a double-buffered construction to enable continuous reception.
Read the RDRH and RDRL registers should be performed only once in the order from the RDRH register to the RDRL
register when a receive data full interrupt (RXI) request is issued. Note that an overrun error occurs when the next frame
of data is received before the received data has been read from the RDRL register.
The CPU cannot write to the RDRH and RDRL registers. Bits 0 to 7 in the RDRH register are fixed to 0. These bits are
read as 0.
The RDRHL register can be accessed in 16-bit units.
Address(es): SCI1.RDRH 0008 A030h, SCI5.RDRH 0008 A0B0h, SCI8.RDRH 0008 A110h, SCI12.RDRH 0008 B310h
Address(es): SCI1.RDRL 0008 A031h, SCI5.RDRL 0008 A0B1h, SCI8.RDRL 0008 A111h, SCI12.RDRL 0008 B311h
Address(es): SCI1.RDRHL 0008 A030h, SCI5.RDRHL 0008 A0B0h, SCI8.RDRHL 0008 A110h, SCI12.RDRHL 0008 B310h
RDRHL
RDRH RDRL
b7 b6 b5 b4 b3 b2 b1 b0 b7 b6 b5 b4 b3 b2 b1 b0
Value after reset:
0000000000000000