ib technology

5

THE RWD HAS THREE POLLING STATES:

1) NO card present and NO host commands received.

Polling cycle rate (time between subsequent CTS low periods) is determined by the

“polling rate” parameter stored in the RWD EEPROM memory. This is typically set

to a long period (0 to 8 seconds, default setting 260mS) and is the primary means to

reduce average power consumption. This is because most of the polling cycle period is

spent in a power-down/sleep mode.

2) EM4102 card in field, NO host commands received.

When a card is detected in the field the polling rate changes to approximately 100ms

(between CTS low periods). This is to ensure that the RWD can respond quickly to the

card leaving the field and a new card being presented.

3) Host commands received and processed.

When the RWD receives commands from the host computer, the polling rate increases

to allow a quick response to the command. This means that commands such as READ

TAG can be repeated quickly with no polling delay (sleep period) between cycles.

5v

0v

Polling cycle

repeats

CTS

TTL levels

Polling cycle period set by RWD EEPROM

parameter (4ms to 8 seconds, default 1 second)

6ms

(CTS timeout)

RF OFF, Power-down/sleep period

RF ON for brief period

(to check for card)

5v

0v

Polling cycle

repeats

CTS

TTL levels

100ms polling rate

6ms (CTS timeout)

RF OFF, Power-down/sleep period

RF ON for brief period (to check for card)

100ms polling rate

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