2001 Oct 04 7
Philips Semiconductors Product specification
HITAG proximity reader module
hardware
HTRM440 family
7.2 Reader module software
Software commands mentioned in this data sheet are fully
described in document
“HTCM400, HTRM440 Family,
HTRM800 Family Interface Protocol Reader - Host”
.
7.3 Reader module hardware
7.3.1 CORE MODULE
The EEPROM on the core module HTCM400 (see Fig.1)
is used to store non-volatile data such as personalization
data, keys, passwords, configurations and status
information.
The microcontroller processes the protocol for the
communication between the transponders and the reader
module. The interface signals are converted in such a way
that HITAG 1 and HITAG 2 transponders are able to
process them and the outgoing signals from the
transponder are converted into interface-compatible
signals. The second essential microcontroller function is
its control function. The microcontroller activates and
deactivates the transmitter, switches the receiver between
the modes for the different transponders reception and
selects the EEPROM.
The transmitter receives data from the microcontroller and
modulates the carrier.
The receiver demodulates the received data and passes
on the data to the microcontroller for further processing.
7.3.2 INTERFACE MICROCONTROLLER TO HOST
The device communicates with the host
(e.g. microcontroller or PC) via a serial interface using a
baud rate of 9600 baud. Data transfer details are: 1 start
bit, 8 data bits, 1 stop bit, no parity bit and the least
significant bit is sent first.
7.3.3 VOLTAGE REGULATION FILTERING
Disturbances on the supply pins may reduce the
performance of the system. For that reason the supply
voltage is filtered but also to limit the spurious emissions at
the supply connections caused by the digital parts of the
module.
7.4 Postal approval
The postal approval can only be granted for final products,
not just for modules like the HTRM440. But the reader
module is designed in a way that it is possible to get the
postal approval for a system including the HTRM440.
Electromagnetic emissions comply with the guidelines in
FTZ 17 TR 2100 and ETS 300 683 and electromagnetic
immunity complies with the guidelines in ETS 300 683.
7.5 Security considerations
Developing the HTRM440 special consideration was given
to aspects of security. The following items represent the
fundamental framework of the security concept:
• Cryptography
• Mutual authentication
• Password verification
• Cyclic Redundancy Check (CRC).
7.5.1 DATA STREAM BETWEEN READER MODULE AND
HITAG 1 TRANSPONDERS
All the commands and data transferred from the reader
module to the transponder are secured by Cyclic
Redundancy Check (CRC). This check is carried out on
the transponder.
Every data stream sent (commands, addresses, user
data) from the proximity reader module to the transponder
is first checked for data errors by the transponder by
means of an integrated 8-bit CRC generator and then
executed. Normally the transponder responds to each
data stream from the proximity reader module with an
acknowledgement signal or with a data block. The CRC is
formed over commands and addresses or the plain data
respectively and in case of crypto mode it is also
encrypted. The generator polynomial of the transponder
CRC generator reads: u
8
+u
4
+u
3
+u
2
+1 = 0x1D.
The CRC pre assignment is 0xFF.
Detailed instructions how to use and calculate CRC are
available at Philips in the following application note
“HT1 (resp. HT2) Transponder family, reliability and
integrity of data transmission”
.
7.5.2 DATA STREAM BETWEEN READER MODULE AND
HITAG 2 TRANSPONDERS
Every command sent from the reader module to the
transponder is checked for data errors by the transponder.
Standard commands transferred from the reader module
to the transponder are divided into two bit streams. The
second bit stream is generated by inverting the bits of the
first bit stream. This redundancy increases data security.
