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1. Data write
2. Transfer from TDR to TSR
3. Serial data output
In case of normal transmission: TEND flag is set
In case of transmit error:
Note: When the ERS flag is set, it should be cleared until transfer of the last bit (D7 in LSB-first
transmission, D0 in MSB-first transmission) of the retransmit data to be transmitted next has
been completed.
Figure 13.6 Relation Between Transmit Operation and Internal Registers
Ds
I/O data
TXI (TEND
interrupt)
Receiving Serial Data: Data reception in smart card mode uses the same processing procedure as
for the normal SCI. Figure 13.8 shows a sample reception processing flowchart.
1. Perform smart card interface mode initialization as described in Initialization above.
2. Check that the ORER flag and PER flag are cleared to 0 in SSR. If either is set, perform the
appropriate receive error handling, then clear both the ORER and the PER flag to 0.
3. Repeat steps 2 and 3 until it can be confirmed that the RDRF flag is set to 1.
4. Read the receive data from RDR.
5. To continue receiving data, clear the RDRF flag to 0 and go back to step 2.
6. To end reception, clear the RE bit to 0.
TDR
Data 1
Data 1
Data 1
Da
Db
Dc
Dd
Figure 13.7 Timing of TEND Flag Setting
TSR
(shift register)
Data 1
ERS flag is set
Steps 2 and 3 above are repeated until the
TEND flag is set.
De
Df
Dg
Dh
12.5 etu
11.0 etu
Data remains in TDR
Data 1
I/O signal
output
Dp
DE
Guard time
When GM = 0
When GM = 1
435
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