AT83C24NDS-PRRUM ATMEL [ATMEL Corporation], AT83C24NDS-PRRUM Datasheet - Page 6

• Manufacturer Part Number: AT83C24NDS-PRRUM
• Description: Smart Card Reader Interface with Power Management
• Manufacturer: ATMEL [ATMEL Corporation]

Operational Modes
TWI Bus Control
TWI Commands
Frame Structure
6
AT83C24
The Atmel Two-wire Interface (TWI) interconnects components on a unique two-wire bus, made
up of one clock line and one data line with speeds of up to 400 Kbits per second, based on a
byte-oriented transfer format.
The TWI-bus interface can be used:
The structure of the TWI bus data frames is made of one or a series of write and read com-
mands completed by STOP.
Write commands to the AT83C24 have the structure:
Read commands to the AT83C24 have the structure:
The ADDRESS BYTE is sampled on A2/CK, A1/RST, A0/3V after each reset (hard/soft/general
call) but A2/CK, A1/RST, A0/3V can be used for transparent mode after the reset.
Figure 1. Data transfer on TWI bus
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ADDRESS BYTE + COMMAND BYTE + DATA BYTE(S)
ADDRESS BYTE + DATA BYTE(S)
To configure the AT83C24
To select the operating mode of the card: 1.8V, 3V or 5V
To configure the automatic activation sequence
To start or stop sessions (activation and de-activation sequences)
To initiate a warm reset
To control the clock to the card in active mode
To control the clock to the card in stand-by mode (stop LOW, stop HIGH or running)
To enter or leave the card stand-by or power-down modes
To select the interface (connection to the host I/O / C4/ C8)
To request the status (card present or not, over-current and out of range supply
voltage occurrence)
To drive and monitor the card contacts by software
To accurately measure the ATR delay when automatic activation is used
SDA
SCL
start condition
1
2
Adresse byte
3
4
5
6
7
acknowledgement
from slave
8
9
command
and/or data
stop condition
4234F–SCR–10/05