AT88SC0404C ATMEL Corporation, AT88SC0404C Datasheet - Page 5

• Manufacturer Part Number: AT88SC0404C
• Description: CryptoMemory 4 Kbit
• Manufacturer: ATMEL Corporation

Protocol Selection
Asynchronous
T = 0 Protocol
Synchronous
2-wire Serial Interface
2023ES–SMEM–07/04
The AT88SC0404C supports two different communication protocols.
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•
The power-up sequence determines which of the two communication protocols will be
used.
This power-up sequence complies with ISO 7816-3 for a cold reset in smart card
applications.
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The device will respond with a 64-bit ATR code, including historical bytes to indicate the
memory density within the CryptoMemory family. Once the asynchronous mode has
been selected, it is not possible to switch to the synchronous mode without powering off
the device.
Figure 2. Asynchronous T = 0 Protocol (Gemplus Patent)
The synchronous mode is the default after powering up V
on RST. For embedded applications using CryptoMemory in standard plastic packages,
this is the only communication protocol.
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Figure 3. Synchronous 2-wire Protocol
Note:
CLK-SCL
CLK-SCL
Smart Card Applications: The asynchronous T = 0 protocol defined by ISO 7816-3
is used for compatibility with the industry’s standard smart card readers.
Embedded Applications: A 2-wire serial interface is used for fast and efficient
communication with logic or controllers.
V
Set I/O-SDA in receive mode.
Provide a clock signal to CLK-SCL.
RST goes high after 400 clock cycles.
Power-up V
After stable V
I/O-SDA
I/O-SDA
CC
Five clock pulses must be sent before the first command is issued.
goes high; RST, I/O-SDA and CLK-SCL are low.
RST
RST
V cc
V cc
CC
CC
, RST goes high also.
, CLK-SCL and I/O-SDA may be driven.
1
2
3
4
5
CC
AT88SC0404C
due to the internal pull-up
ATR
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