ST8024 データシートの表示（PDF） - STMicroelectronics

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コンポーネント説明

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ST8024

Smartcard interface

STMicroelectronics 

ST8024

Functional description

5.5

Inactive mode

After a power-on reset, the circuit enters the inactive mode. A minimum number of circuits

are active while waiting for the microcontroller to start a session:

– All card contacts are inactive (approximately 200 Ω to GND)

– Pins I/OUC, AUX1UC and AUX2UC are in the high-impedance state (11 kΩ pull-up

resistor to VDD)

– Voltage generators are stopped

– XTAL oscillator is running

– Voltage supervisor is active

– The internal oscillator is running at its low frequency.

5.6

Activation sequence

After power-on and after the internal pulse width delay, the system microcontroller can

check the presence of a card using the signals OFF and CMDVCC as shown in Table 22.

If the card is in the reader (this is the case if PRES or PRES is active), the system

microcontroller can start a card session by pulling CMDVCC LOW. The following sequence

then occurs (see Figure 6):

1. CMDVCC is pulled LOW and the internal oscillator changes to its high frequency (t0).

2. The voltage doubler is started (between t0 and t1).

3. VCC rises from 0 to 5 V (or 3 V) with a controlled slope (t2 = t1 + 1.5 x T) where T is

64 times the period of the internal oscillator (approximately 25 µs).

4. I/O, AUX1 and AUX2 are enabled (t3 = t1 + 4T) (these were pulled LOW until this

moment).

5. CLK is applied to the C3 contact of the card reader (t4).

6. RST is enabled (t5 = t1 + 7T).

The clock may be applied to the card using the following sequence (see Figure 5):

1. Set RSTIN HIGH.

2. Set CMDVCC LOW.

3. Reset RSTIN LOW between t3 and t5; CLK will start at this moment.

4. RST remains LOW until t5, when RST is enabled to be the copy of RSTIN.

5. After t5, RSTIN has no further affect on CLK; this allows a precise count of CLK

pulses before toggling RST.

If the applied clock is not needed, then CMDVCC may be set LOW with RSTIN LOW. In this

case, CLK will start at t3 (minimum 200 ns after the transition on I/O), and after t5, RSTIN

may be set HIGH in order to obtain an Answer To Request (ATR) from the card.

Activation should not be performed with RSTIN held permanently HIGH

Table 22.

Card presence indicator

OFF

CMDVCC

H

H

L

H

Indication

Card present

Card not present

19/31

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