HD6432633 Datasheet, PDF (833/1453 Pages) Renesas Technology Corp – Series of Microcomputers (MCUs: microcomputer units)

17.3 Operation
17.3.1 Overview
The main functions of the Smart Card interface are as follows.
• One frame consists of 8-bit data plus a parity bit.
• In transmission, a guard time of at least 2 etu (1 etu in the block transfer mode) is left between
the end of the parity bit and the start of the next frame.
• If a parity error is detected during reception, a low error signal level is output for one etu
period, 10.5 etu after the start bit.
• If the error signal is sampled during transmission, the same data is transmitted automatically
after the elapse of 2 etu or longer. (except in block transfer mode)
• Only asynchronous communication is supported; there is no clocked synchronous
communication function.
Note: etu: Elementary time unit (time for transfer of 1 bit)
17.3.2 Pin Connections
Figure 17-2 shows a schematic diagram of Smart Card interface related pin connections.
In communication with an IC card, since both transmission and reception are carried out on a
single data transmission line, the TxD pin and RxD pin should be connected with the LSI pin. The
data transmission line should be pulled up to the V_CC power supply with a resistor.
When the clock generated on the Smart Card interface is used by an IC card, the SCK pin output is
input to the CLK pin of the IC card. No connection is needed if the IC card uses an internal clock.
LSI port output is used as the reset signal.
Other pins must normally be connected to the power supply or ground.
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