RX610 Group
20. Serial Communications Interface (SCI)
R01UH0032EJ0120 Rev.1.20
Page 666 of 1006
Feb 20, 2013
20.5.6
Serial Data Transmission (Except in Block Transfer Mode)
Serial data transmission in smart card interface mode (except in block transfer mode) is different from that in normal
serial communications interface mode in that an error signal is sampled and data can be re-transmitted. Figure 20.25
shows the data re-transfer operation during transmission.
1. When an error signal from the receiving end is sampled after one-frame data has been transmitted, the ERS flag in
SSR is set to 1. If the RIE bit in SCR is set to 1 at this time, an ERI interrupt request is generated. Clear the ERS flag
to 0 before the next parity bit is sampled.
2. For a frame in which an error signal is received, the SSR.TEND flag is not set. Data is re-transferred from TDR to
TSR allowing automatic data retransmission.
3. If no error signal is returned from the receiving end, the ERS flag in SSR is not set to 1.
4. In this case, the SCI judges that transmission of one-frame data (including retransfer) has been completed, and the
SSR.TEND flag is set. If the TIE bit in SCR is set to 1 at this time, a TXI interrupt request is generated. Writing
transmit data to TDR starts transmission of the next data.
Figure 20.27 shows a sample flowchart of serial transmission. All the processing steps are automatically performed using
a TXI interrupt request to activate the DTC or DMAC.
When the SSR.TEND flag is set to 1 in transmission, if the TIE bit in SCR is set to 1, a TXI interrupt request is generated.
The DTC or DMAC is activated by a TXI interrupt request if the TXI interrupt request is specified as a source of DTC or
DMAC activation beforehand, allowing transfer of transmit data. The TEND flag is automatically cleared to 0 when the
DTC or DMAC transfers the data.
If an error occurs, the SCI automatically re-transmits the same data. During this retransmission, the TEND flag is kept to
0 and the DTC or DMAC is not activated. Therefore, the SCI and DTC or DMAC automatically transmit the specified
number of bytes, including retransmission in the case of error occurrence. However, since the ERS flag is not
automatically cleared; set the RIE bit to 1 beforehand to enable an ERI interrupt request to be generated at error
occurrence, and clear the ERS flag to 0.
When transmitting/receiving data using the DTC or DMAC, be sure to make settings to enable the DTC or DMAC before
making SCI settings.
For DTC or DMAC settings, see section 12, DMA Controller (DMAC) and section 13, Data Transfer Controller (DTC).
Retransfer frame
n-th transfer frame
(n+1)- h transfer
frame
[1]
[2]
[4]
[3]
(DE)
SSR.FER flag/
SSR.ERS flag
Ds D0 D1 D2
D6 D7 Dp
D3 D4 D5
DE
D6 D7 Dp
D5
TXI interrupt signal
Note:
*
For the corresponding interrupt vector number, see section 10, Interrupt Control Unit (ICU).
Ds D0 D1 D2 D3 D4
Ds D0 D1 D2 D3 D4
Figure 20.25 Data Retransfer Operation in SCI Transmission Mode
Summary of Contents for RX600 Series
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