AT88SC0404C_09 Datasheet, PDF (11/20 Pages) ATMEL Corporation – CryptoMemory 4 Kbit

AT88SC0404C
9.2.
Synchronous 2-wire Serial Interface
The synchronous mode is the default after powering up V_CC due to an internal pull-up on RST. For embedded
applications using CryptoMemory in standard plastic packages, this is the only communication protocol.
• Power-up V_CC, RST goes high also.
• After stable V_CC, CLK-SCL and I/O-SDA may be driven.
Figure 11. Synchronous 2-wire Protocol
Vcc
I/O-SDA
RST
CLK-SCL
1 2345
Note: Five clock pulses must be sent before the first command is issued.
10. Communication Security Modes
Communications between the device and host operate in three basic modes. Standard mode is the default mode for
the device after power-up. Authentication mode is activated by a successful authentication sequence. Encryption mode
is activated by a successful encryption activation following a successful authentication.
Table 4.
Communication Security Modes⁽¹⁾
Mode
Configuration Data
Standard
clear
Authentication
clear
Encryption
clear
User Data
clear
clear
encrypted
Passwords
clear
encrypted
encrypted
Data Integrity Check
MDC⁽¹⁾
MAC⁽¹⁾
MAC⁽¹⁾
Note:
1. Configuration data include viewable areas of the Configuration Zone except the passwords:
MDC: Modification Detection Code
MAC: Message Authentication Code.
11
2023KS–SMEM–10/09