ib technology
Auxiliary Data Output
The Micro RWD MF LP version uses the 4-byte UID (serial number) or the least significant
(first) 4 bytes of data from a Mifare card memory block to create a 32-bit data frame. The data
frame can then be output as asynchronous 9600 baud serial data on OP0 pin or as 24 / 32 bit
Wiegand 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 (pin 20)
to the main TX output (pin 23). This allows both bi-directional command/data
communication and the automatic 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 (to avoid confusion of data).
For normal command and data response, the serial auxiliary output MUST be directed
to the OP0 pin or turned OFF.
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, data source, byte
order and Hex/ASCII format for the auxiliary output and the various Wiegand protocol
options are all controlled by programmable RWD EEPROM parameters (see page 8). A zero
data length parameter effectively turns the auxiliary outputs OFF.
In this manner the MicroRWD can be used in battery powered application (down to 150µA
average current consumption) and automatically output blocks of data (such as the UID)
WITHOUT any commands being 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 “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.
Note that setting Polling rate parameter to minimum value (0x00) means the polling rate
is always as fast as possible and does not change (“SLEEP” and power-down is skipped).
MicroRWD MF (Mifare) operation
The Mifare transponder cards have significantly more memory than most other cards and the
13.56 MHz carrier frequency provides fast transaction times of 106 kbaud. The cards are
available with 64 bytes (Mifare Ultralight), 1024 bytes (Mifare 1k) and 4096 bytes (Mifare
4k) of memory. For the 1k and 4k cards the memory is organised as 16 and 40 Sectors
respectively, each Sector has 64 bytes arranged as 4 Blocks of memory (3 of which are
available for general Read/Write use). Each Sector can be separately locked/unlocked for
access using security keys. Initial communication with the cards can only proceed after
mutual authentication between the RWD and the card has succeeded (as defined by ISO
14443A standard). The Mifare cards are ideally suited to Electronic-Purse applications such
as ticketing and vending applications where each sector can hold entirely separate data for
different applications.
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