LRI2K datasheet(45/89 Pages) STMICROELECTRONICS

45 / 89 page

LRI2K

Timing definition

45/89

Timing definition

19.1

t1: LRI2K response delay

Upon detection of the rising edge of the EOF received from the VCD, the LRI2K waits for a

time t1nom before transmitting its response to a VCD request or before switching to the next

slot during an inventory process. Values of t1 are given in Table 19. The EOF is defined in

Figure 11 on page 18.

19.2

t2: VCD new request delay

t2 is the time after which the VCD may send an EOF to switch to the next slot when one or

more LRI2K responses have been received during an Inventory command. It starts from the

reception of the EOF from the LRI2Ks.

The EOF sent by the VCD may be either 10% or 100% modulated regardless of the

modulation index used for transmitting the VCD request to the LRI2K.

t2 is also the time after which the VCD may send a new request to the LRI2K as described in

Table 37: LRI2K protocol timing.

Values of t2 are given in Table 19.

19.3

t3: VCD new request delay in the absence of a response from

the LRI2K

t3 is the time after which the VCD may send an EOF to switch to the next slot when no

LRI2K response has been received.

The EOF sent by the VCD may be either 10% or 100% modulated regardless of the

modulation index used for transmitting the VCD request to the LRI2K.

From the time the VCD has generated the rising edge of an EOF:

●

If this EOF is 100% modulated, the VCD waits a time at least equal to t3min before

sending a new EOF.

●

If this EOF is 10% modulated, the VCD waits a time at least equal to the sum of t3min +

the LRI2K nominal response time (which depends on the LRI2K data rate and

subcarrier modulation mode) before sending a new EOF.

Table 19.

Timing values(1)

The tolerance of specific timings is ± 32/fC.

Minimum (min) values

Nominal (nom) values

Maximum (max) values

318.6 µs

320.9 µs

323.3 µs

309.2 µs

No tnom

No tmax

t1max

(2) + t

SOF

(3)

t1max does not apply for write alike requests. Timing conditions for write alike requests are defined in the

command description.

tSOF is the time taken by the LRI2K to transmit an SOF to the VCD. tSOF depends on the current data rate:

High data rate or Low data rate.

No tnom

No tmax

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