HD6473032F16 Datasheet, PDF (535/847 Pages) Renesas Technology Corp – Hardware Manual Renesas 16-Bit Single-Chip Microcomputer H8 Family/H8/300H Series

Section 14 Smart Card Interface
14.3.3 Data Format
Figure 14.3 shows the data format of the smart card interface. In receive mode, parity is checked
once per frame. If a parity error is detected, an error signal is returned to the transmitting device to
request retransmission. In transmit mode, the error signal is sampled and the same data is
retransmitted if the error signal is low.
No parity error
Ds D0 D1 D2 D3 D4 D5 D6 D7 Dp
Output from transmitting device
Parity error
Ds D0 D1 D2 D3 D4 D5 D6 D7 Dp
DE
Output from transmitting device
Ds:
Start bit
D0 to D7: Data bits
Dp:
Parity bit
DE:
Error signal
Output from
receiving device
Figure 14.3 Smart Card Interface Data Format
The operating sequence is as follows.
1. When not in use, the data line is in the high-impedance state, and is pulled up to the high level
through a resistor.
2. To start transmitting a frame of data, the transmitting device transmits a low start bit (Ds),
followed by eight data bits (D0 to D7) and a parity bit (Dp).
3. Next, in the smart card interface, the transmitting device returns the data line to the high-
impedance state. The data line is pulled up to the high level through a resistor.
4. The receiving device performs a parity check. If there is no parity error, the receiving device
waits to receive the next data. If a parity error is present, the receiving device outputs a low
error signal (DE) to request retransmission of the data. After outputting the error signal for a
Rev. 3.00 Mar 21, 2006 page 505 of 814
REJ09B0302-0300