Datasheet

Table Of Contents
Section 18 Serial Communication Interface 4 (SCI4)
Rev. 2.00 Jul. 04, 2007 Page 429 of 692
REJ09B0309-0200
Notes: 1. When switching from transmission to simultaneous data transmission and reception,
confirm that the SCI4 completes transmission and both the TDRE and TEND bits are
set to 1. After that, clear the TE bit to 0 and then set both the TE and RE bits to 1.
2. When switching from reception to simultaneous data transmission and reception,
confirm that the SCI4 completes reception and both the RDRF and ORER flags are
cleared to 0 after clearing the RE bit to 0. After that, set both the TE and RE bits to 1.
18.5 Interrupt Sources
The SCI4 has four interrupt sources: transmit end, transmit data empty, receive data full, and
receive error (overrun error).
Table 18.3 lists the descriptions of the interrupt sources.
Table 18.3 SCI4 Interrupt Sources
Abbreviation Condition Interrupt Source
RXI RIE = 1 Receive data full (RDRF)
TXI TIE = 1 Transmit data empty (TDRE)
TEI TEIE = 1 Transmit end (TEND)
ERI RIE = 1 Receive error (ORER)
The interrupt requests can be enabled/disabled by the TIE and RIE bits in SCR4.
When the TDRE flag in SCSR4 is set to 1, a TXI is generated. When the TEND bit in SCSR4 is
set to 1, a TEI is generated. These two interrupt requests are generated during transmission.
The TDRE flag in SCSR4 is initialized to 1. Therefore, if a TXI request is enabled by setting the
TIE bit in SCR4 to 1 before transmit data is transferred to TDR4, a TXI is generated even when
transmit data is not ready.
If transmit data is transferred to TDR4 in the interrupt handling routine, these interrupt requests
can be effectively used.
To avoid the occurrence of the interrupt requests (TXI and TEI), clear the corresponding interrupt
enable bits (TIE and TEIE) to 0 after transmit data is transferred to TDR4.
When the RDRF bit in SCSR4 is set to 1, an RXI is generated. When the ORER flag is set to 1, an
ERI is generated. These two interrupt requests are generated during reception.