ib technology

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Data is only accepted from the EM4102 transponder if the memory parity bits are valid. This

configuration ensures that the integrity of user data is maintained.

The EM4102 transponder type is widely used throughout the world in its base form and also

in many fully compatible derivative forms. The Microchip MCRF200/123 transponder has

the same modulation and timing characteristics as the EM4102 types but has a 16-byte read-

only memory. MCRF200/123 Reader mode can be selected by setting the appropriate RWD

EEPROM parameters.

Auxiliary Data Output

The Micro RWD EM4102 LP version uses the least significant 4-bytes of the 5-byte UID

(serial number) to create a 32-bit data frame. The first byte of the 5-byte EM4102 data is

ignored. The data frame can then be output as asynchronous 9600 baud serial data on OP0

pin or as 24 / 32 bit Weigand protocol with parity bits attached (making 26 or 34 bits of data)

on OP0 / OP1 pins.

An RWD EEPROM parameter can redirect the serial auxiliary output on OP0 to the

main TX output (pin 23). This is to allow both bi-directional command/data

communication and the uni-directional auxiliary serial data output with the same 3-wire

RS232 interface. Note that when the auxiliary serial output has been redirected to TX

pin, there will be NO acknowledgement or data response to commands.

For normal command and data response using the Windows application, the serial

auxiliary output MUST be directed to the OP0 pin.

The auxiliary data outputs on OP0 / OP1 are AUTOMATIC and if enabled, occur when a

card enters the RF field for the first time. The “beep” output signal delay, the data source and

byte order for the auxiliary output and the various Weigand protocol options are all controlled

by programmable RWD EEPROM parameters (see page 10). A zero data length parameter

effectively turns the auxiliary outputs OFF (factory default set to asynchronous serial output

of UID-serial number from OP0 with NO “beep” output).

In this manner the MicroRWD EM4102 LP can be used in a battery powered application

(<100µA average current consumption) and automatically output a 4-byte serial number

WITHOUT any commands having to be sent to the module. In addition, the “Green” LED

output or the BEEP output can be used as a control signal to “interrupt” the host computer or

microcontroller just before the automatic data is transmitted.

NOTE that the “BEEP” output (RWD pin 4) idles in a high state and is an open drain output

so it “sinks” current. External loads can be connected between the supply rail and pin 4 with

a series resistor to ensure “sink” current does not exceed 25ma.

MicroRWD EM4102 LP operation

The MicroRWD is essentially a proximity system and a Read range of up to 20cm can be

achieved. The unique AST (Adaptive Sampling) feature allows the RWD to continually adjust

and re-tune the sampling to allow for inductive changes in the RF field, an essential feature

for real-world reliability and robust operation.