MLX90111 データシートの表示（PDF） - Unspecified

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MLX90111

128bit Read Write Transponder

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MLX90111

128bit Read Write Transponder

2. Operating Modes

2.1 Continuous/critical read mode (ID)

In read mode, the transponder transmits its ID

code to a transceiver by amplitude modulating

(AM) the envelope of the carrier coming from the

transceiver. The 128 bits of the ID are

Manchester or Biphase encoded.

After POR the device will enter 'normal' read

mode. The ID will be read out under optimal

conditions. After programming any word of the

ID, the device will automatically enter 'critical'

read mode. The data is read at the 2 extremes

of the reading window. When both readings are

identical, the data retention is guaranteed as

specified (Tret, Ncyc). If the two critical readings

show a difference, the device is at its minimum

coupling with the transceiver and it should be

reprogrammed using a stronger field.

Critical read mode can only be reset by

removing the transponder from the RF field.

2.2 Programming mode

Upon receiving an Asynchronous Control

Pattern (ACP), the device enters program mode

and waits during a Watchdog Delay period

(TWD), for the start bit of the programming

sequence.

The programming sequence consists of a start

bit, and a 32 bit command. The command starts

with a 3bit Command Field (CMF), a 4bit

address, an odd parity bit calculated over the

address, a 16bit data word and an 8bit CRC

calculated over the full command.

If the programming sequence is received, the

write access, parity and CRC are verified and

command is executed if possible, else the

transponders goes back into normal read mode.

In case the command has been executed, the

transponder waits again for a Watchdog Delay

period TWD for a new programming command.

In case of a timeout the device starts sending

the ID code in critical read mode, until removal

from the RF field.

Minimum field strength for reliable programming is

set by the minimum induced e.m.f. Vacee on the

transponder coil.

2.3 Programming commands

Two Command Fields are defined:

CMF

CMF1

CMF2

Code

001

000

Action

- Write ID words: addresses 0…7,

- Read address 8,9,10

- Write address 8,9,10

To write data, the respective CMF and address

are sent out. If the write access, parity and CRC

are verified, the data are written in the EEPROM

at the specified location. For 2kbaud devices

EEPROM programming takes 20ms, for 4kbaud

devices programming is done in 10ms.

To read the data in addresses 8, 9 and 10 CMF1

is used.

- address 11 for reading the configuration word.

- address 12 for reading the tuning (bit positions

14 to 10) and the configuration (bit positions 0 to

1) bits, see the memory map.

If the parity and CRC are verified, the data is

sent out during the time window normally

allocated for the EEPROM programming. Data

is sent with a start bit of ½ bit (!) time first,

followed by twice the 16-bit data word, with

critical read levels. The startbit allows to detect

a leading 0 in Manchester coding, and allows the

microcontroller to synchronize. Remark that this

startbit is different from the start bit sent by the

reader, which is a full bit.

HINT: In case the reader requires more time to

switch from write to read mode, the dummy data

should be chosen such that the last CRC bits

are 1, i.e. in Return to Zero code: no modulation

needed on the reader antenna. This way the

time for switching the reader can be extended.

2.3 Parity, CRC

PAR is an odd Parity bit is calculated over the 4-

bit address

The 8-bit CRC with polynomial u8+ u4+ u3+ u2+

u0 is calculated over the complete command

string [CMF-ADDRESS-PAR-DATA].

u2

u3

76

5

LSB

Exclusive OR

x Register Stage

u4

4

u8

3210

MSB

Data

MLX90111 128bit Read Write Transponder Page 7 of 12

Rev 1.12 5-Feb-01

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