MLX90121

13.56MHz RFID Transceiver

3901090121

Page 13 of 26

Data Sheet

Rev. 007

Jan-2008

ISO Examples

Norm

Symbol

Time

Bit

Time

EncTimeRef

ISO15693 (1 out of 4)

ISO15693 (1 out of 256)

ISO14443

75.52

µs

18.88

µs

9.44

µs

9.44

µs

2.36

µs

1.18

µs

0x1F (11111)

0x07 (00111)

0x03 (00011)

Symbol Transmission

CK and DIN inputs are used to transmit symbols. On each rising edge of the CK signal, DIN is sampled to

encode the address of the corresponding symbol. This means that each address of the seven available

symbols can be encoded with a maximum of three bits (meaning three CK pulses). To reduce the usage

of the microcontroller for fast protocol, Sym0 and Sym1 can be transmitted with only one bit and, Sym2

and Sym3 with two bits, as shown in the following table.

Symbol

First Symbol

3 bits are needed to

initiate Transmission

Subsequent Symbols

Reduced encoding

possible (minimum 1 bit)

Sym0

Sym1

Sym2

Sym3

Sym4

Sym5

Sym6 (*)

000

001

010

011

100

101

110

0

1

10

11

100

101

110

(*) Symbol 6 is hard coded to 0xFF (11111111).

To initiate a transmission, it is necessary to send the first symbol with three CK pulses to initialize the

communication. On every rising edge of DSYNC, the following symbol is sent. To complete the

transmission, no more CK pulse should be sent after EOF symbol.

Sym2

Sym0

Sym3

Sym5

Sym2

Sym0

Sym3

Sym5

DIN

CK

DSYNC

Modulation

3 CK pulses are mandatory

to start transmission

N e x t m o d u l a t i o n d a t a

available after the rising

edge of DSYNC

No CK pulse to complete

the transmission