BioSIMKey - ADT60 Reference Manual
rev 1.0, April, 2002
Advanced Card Systems Ltd.
Page 9 of 26
7. PC-READER
COMMUNICATION
PROTOCOL
In normal operation, the BioSIMKey smart card reader acts as a slave with regard to the
communication between a computer and the device. The communication is carried out in the
form of successive command-response exchanges. The computer transmits a command to
the reader and receives a response from the reader after the command has been executed. A
new command can be transmitted to the BioSIMKey smartcard reader only after the response
to the previous command has been received.
There are only two cases where the reader transmits data without having received a
command from the computer, namely, the Reset Message of the reader and the Card Status
Message.
7.1 Command
7.1.1 Normal Command (Length < 255 bytes)
A command consists of four protocol bytes and a variable number of data bytes and has the
following structure:
Byte
1
2
3
4 ... N+3 (0<N<255)
N+4
Header
Instruction
Data length = N
Data
Checksum
Header
Always
01
H
to indicate the start of a command.
Instruction
The instruction code of the command to be carried out by the BioSIMKey
Data Length
Number of subsequent data bytes.(0 < N < 255)
Data
Data contents of the command.
For a READ command, for example, the data bytes would specify the start
address and the number of bytes to be read. For a WRITE command, the
data bytes would specify the start address and the data to be written to the
card.
The data bytes can represent values to be written to a card and/or command
parameters such as an address, a counter, etc.
Checksum
The checksum is computed by XORing all command bytes including header,
instruction, data length and all data bytes.
