HTCM400/EAE,122 Datasheet HTCM400/EAE,122 | P7-P9

2001 Oct 04 7

Philips Semiconductors Product speciﬁcation

HITAG core module hardware HTCM400

7.1.5 BEHAVIOUR WITH SEVERAL TRANSPONDERS

If several HITAG transponders arrive simultaneously

within the communication field of the antenna of a HITAG

proximity reader module, the ‘stronger’ transponder (the

nearer one) takes over or - under special circumstances -

no communication takes place. If the transponders arrive

in the field one after the other, communication is

established with the first one, all other transponders are

ignored.

Nevertheless, it is possible to mute transponders so that

several HITAG transponders can be accessed

sequentially. This ensures that no two (or several) HITAG

transponders will ever be processed (above all written to)

accidentally at the same time.

If a HITAG long range reader module is used, anticollision

mode is applied, which makes it possible to read and write

all the HITAG 1 transponders (theoretical up to 2

) within

the communication field of the antenna simultaneously.

Because of the mutual influence of the transponder coils -

they detune each other if there are too many too close to

each other - the number of the transponders that can be

operated simultaneously is limited.

7.2 Core module software

The software description is given in document “

HTCM400,

HTRM440 Family, HTRM800 Family Interface Protocol

Reader - Host

”.

7.3 Core module hardware

7.3.1 EEPROM

The EEPROM is used to store non-volatile data such as

personalization data, keys, passwords, configurations and

status information.

7.3.2 MICROCONTROLLER

The microcontroller processes the protocol for the

communication between the transponders and the read

and write unit. The interface signals are converted so that

a HITAG 1 or HITAG 2 transponder is 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 and selects the EEPROM.

7.3.3 INTERFACE: MICROCONTROLLER - HOST

The device communicates with the host (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

and no parity bit, the least significant bit is sent first.

An RS232 interface device can be connected to the

HTCM400. Optionally an RS422 or an RS485 device is

possible.

7.3.4 TRANSMITTER AND RECEIVER

The transmitter receives data from the microcontroller and

modulates the carrier.

The receiver demodulates the received data and passes

them on to the microcontroller for further processing.

7.3.5 ANTENNA

For the design of HITAG proximity antennas, see

Section 11.

7.3.6 HITAG LONG RANGE READER MODULE

The HITAG long range reader module (HTRM800)

supplied by Philips uses some of the module pins as

interface to an additional high frequency part and a Digital

Signal Processor (DSP) part.

7.3.7 INTERFACE: MICROCONTROLLER - HITAG LONG

RANGE BOARD

This interface is not wired with proximity applications

(leave pins open).

2001 Oct 04 8

Philips Semiconductors Product speciﬁcation

HITAG core module hardware HTCM400

7.4 Postal approval

The postal approval can only be granted for final products,

not just for components like the HTCM400. But the core

module is designed in a way that it is possible to get the

postal approval for a device including the HTCM400, if you

follow the design instructions given by Philips.

Electromagnetic emission comply with the guidelines in

FTZ 17 TR 2100 and ETS 300 683. Electromagnetic

immunity complies with the guidelines in ETS 300 683.

7.4.1 COMMON MODE FILTERING

Figure 5 shows the basic configuration using the

HTCM400 used to comply with the standards and some

additional circuits which are recommended.

handbook, full pagewidth

MGW326

1 nF

DVDD,

AVDD

DGND,

AGND

1 nF

ANTENNA

RS232-

interface

power

supply

5 V DC

100

(1)

1 nF 1 nF

TxD

RxD

GND

1 nF

TX1

AGND

HTCM400

1 nF

Fig.5 Common mode filtering.

(1) SMD filter Murata NFM61R10T102.

The design consists of a virtual ground layer (drawn grey

in Fig.5). All entering wires are blocked by 1 nF ceramic

capacitors to this layer to prevent common mode

disturbances from entering the following circuits. The

virtual ground layer is floating, it is not connected to the

ground itself.

A recommended metal housing that covers the HTCM400

would also be connected to the floating layer.

2001 Oct 04 9

Philips Semiconductors Product speciﬁcation

HITAG core module hardware HTCM400

7.4.2 FILTERING OF THE SUPPLY VOLTAGES

The transmitter of the HTCM400 is supplied via pins AVDD and AGND. Disturbances on these supply pins are amplified

and may reduce the performance of the system. For that reason especially the analog supply voltage (pin AVDD) must

be filtered in addition to the common mode filtering described in Fig.5.

On the other hand the spurious emissions at the supply connections (pins DVDD and DGND) caused by the digital parts

of the module must be limited.

A suppressor diode protects the core module from ESD to the power supply line (see Fig.6).

7.4.3 FILTERING OF THE ANTENNA CIRCUIT

In case of using an external antenna with shielded antenna cable, no additional filtering should be necessary. In case of

a heavy disturbed environment, an additional filter circuit is recommended when using external antennas (see Fig.7).

Using this filter will reduce the reading performance by approximately 20%.

7.4.4 ESD PROTECTION

All I/Os should be protected by common circuits consisting of series resistors and suppressor diodes. The transmitter

output is already protected by a series resistor and internal diodes of the driving FETs. To protect the receiver’s input, a

40 V bi-directional suppresser diode at pin TX1 is recommended. If the additional filter shown in Fig.7 is used, no more

protection circuits are needed.

handbook, full pagewidth

MGW327

100

100 nF

DVDD

AVDD

AGND,

DGND

µF

18 V

suppressor

GND

10 µH

100 µH

10 µH

HTCM400

Fig.6 Power supply filtering.

handbook, halfpage

MGW328

2.2 kΩ

kΩ

1.68

TX1

GND

ANTENNA

HTCM400

Fig.7 Filtering of the antenna circuit.

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HTCM400/EAE,122

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Manufacturer:

NXP Semiconductors

Description:

IC RFID READER 125KHZ MODULE

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HTCM400/EAE,122