SH7763 Datasheet, PDF (1242/2026 Pages) Renesas Technology Corp – Renesas 32-Bit RISC Microcomputer SuperHTM RISC Engine Family SH-4A Series

Section 28 Serial Communication Interface with FIFO/IrDA Interface (SCIF/IrDA)
28.4.5 Usage Notes
Note the following when using the SCIF.
(1) SCFTDR Writing and the TDFE Flag
The TDFE flag in SCFSR is set when the number of transmit data bytes written in SCFTDR has
fallen to or below the transmit trigger number set by bits TTRG1 and TTRG0 in SCFCR. After
TDFE is set, transmit data up to the number of empty bytes in SCFTDR can be written, allowing
efficient continuous transmission.
However, if the number of data bytes written in SCFTDR is equal to or less than the transmit
trigger number, the TDFE flag will be set to 1 again, even after being read as 1 and cleared to 0.
TDFE clearing should therefore be carried out when SCFTDR contains more than the transmit
trigger number of transmit data bytes.
The number of transmit data bytes in SCFTDR can be found from SCFDR.
(2) SCFRDR Reading and the RDF Flag
The RDF flag in SCFSR is set when the number of receive data bytes in SCFRDR has become
equal to or greater than the receive trigger number set by bits RTRG1 and RTRG0 in SCFCR.
After RDF is set, receive data equivalent to the trigger number can be read from SCFRDR,
allowing efficient continuous reception.
However, if the number of data bytes read in SCFRDR is equal to or greater than the trigger
number, the RDF flag will be set to 1 again even if it is cleared to 0. After the receive data is
read, clear the RDF flag readout to 0 in order to reduce the number of data bytes in SCFRDR to
less than the trigger number.
The number of receive data bytes in SCFRDR can be found from SCRFDR.
(3) Break Detection and Processing
If a framing error (FER) is detected, break signals can also be detected by reading the SCIF_RXD
pin value directly. In the break state the input from the SCIF_RXD pin consists of all 0s, so the
FER flag is set and the parity error flag (PER) may also be set.
Although the SCIF stops transferring receive data to SCFRDR after receiving a break, the receive
operation continues.
Rev. 1.00 Oct. 01, 2007 Page 1176 of 1956
REJ09B0256-0100