SH7059 Datasheet, PDF (484/1042 Pages) Renesas Technology Corp – 32-Bit RISC Microcomputer

15. Serial Communication Interface (SCI)
ERI is requested when the ORER, PER, or FER bit in SSR is set to 1. ERI cannot start the DMAC.
TEI is requested when the TEND bit in SSR is set to 1. TEI cannot start the DMAC. Where the TXI interrupt indicates that
transmit data writing is enabled, the TEI interrupt indicates that the transmit operation is complete.
Table 15.12 SCI Interrupt Sources
Interrupt Source
ERI
RXI
TXI
TEI
Description
Receive error (ORER, PER, or FER)
Receive data full (RDRF)
Transmit data empty (TDRE)
Transmit end (TEND)
DMAC Activation
No
Yes
Yes
No
Priority
High
Low
15.5 Usage Notes
Sections 15.5.1 to 15.5.10 provide information concerning use of the SCI.
15.5.1 TDR Write and TDRE Flag
The TDRE bit in the serial status register (SSR) is a status flag indicating loading of transmit data from TDR into TSR.
The SCI sets TDRE to 1 when it transfers data from TDR to TSR. Data can be written to TDR regardless of the TDRE bit
status. If new data is written in TDR when TDRE is 0, however, the old data stored in TDR will be lost because the data
has not yet been transferred to TSR. Before writing transmit data to TDR, be sure to check that TDRE is set to 1.
15.5.2 Simultaneous Multiple Receive Errors
Table 15.13 indicates the state of the SSR status flags when multiple receive errors occur simultaneously. When an
overrun error occurs, the RSR contents cannot be transferred to RDR, so receive data is lost.
Table 15.13 SSR Status Flags and Transfer of Receive Data
SSR Status Flags
Receive Error Status
RDRF ORER FER
PER
Overrun error
1
1
0
0
Framing error
0
0
1
0
Parity error
0
0
0
1
Overrun error + framing error
1
1
1
0
Overrun error + parity error
1
1
0
1
Framing error + parity error
0
0
1
1
Overrun error + framing error + parity 1
1
1
1
error
Legend:
O: Receive data is transferred from RSR to RDR.
X: Receive data is not transferred from RSR to RDR.
Receive Data Transfer
RSR → RDR
X
O
O
X
X
O
X
Rev.3.00 Mar. 12, 2008 Page 394 of 948
REJ09B0177-0300