r4f2426 Renesas Electronics Corporation., r4f2426 Datasheet - Page 929

• Manufacturer Part Number: r4f2426
• Description: 16-bit Single-chip Microcomputer H8s Family / H8s/2400 Series
• Manufacturer: Renesas Electronics Corporation.

4. Transmission of one frame, including a retransfer, is judged to have been completed, and the
Figure 15.28 shows a flowchart for transmission. The sequence of transmit operations can be
performed automatically by specifying the DTC or DMAC to be activated with a TXI interrupt
source. In a transmit operation, the TDRE flag is also set to 1 at the same time as the TEND flag in
SSR, and a TXI interrupt will be generated if the TIE bit in SCR has been set to 1. If the TXI
request is designated beforehand as a DTC or DMAC activation source, the DTC or DMAC will
be activated by the TXI request, and transfer of the transmit data will be carried out. The TDRE
and TEND flags are automatically cleared to 0 when data transfer is performed by the DTC or
DMAC. In the event of an error, the SCI retransmits the same data automatically. During this
period, the TEND flag remains cleared to 0 and the DTC or DMAC is not activated. Therefore, the
SCI and DTC or DMAC will automatically transmit the specified number of bytes in the event of
an error, including retransmission. However, the ERS flag is not cleared automatically when an
error occurs, and so the RIE bit should be set to 1 beforehand so that an ERI request will be
generated in the event of an error, and the ERS flag will be cleared.
When performing transfer using the DTC or DMAC, it is essential to set and enable the DTC or
DMAC before carrying out SCI setting. For details on the DTC or DMAC setting procedures,
refer to section 9, Data Transfer Controller (DTC) or section 7, DMA Controller (DMAC).
TDRE
TEND
FER/ERS
TEND bit in SSR is set to 1. If the TIE bit in SCR is set at this time, a TXI interrupt request is
generated. Writing transmit data to TDR transfers the next transmit data.
Ds
Transfer to TSR from TDR
D0 D1 D2 D3 D4 D5 D6 D7 Dp DE
Figure 15.26 Retransfer Operation in SCI Transmit Mode
nth transfer frame
[1]
[2]
Ds D0 D1 D2 D3 D4 D5 D6 D7 Dp
Transfer to TSR from TDR
Section 15 Serial Communication Interface (SCI, IrDA)
Retransferred frame
Rev. 1.00 Sep. 19, 2008 Page 901 of 1270
(DE)
[3]
[4]
Ds D0 D1 D2 D3 D4
Transfer to TSR
REJ09B0466-0100
Transfer
frame n+1
from TDR