TSS461C datasheet(46/57 Pages) ATMEL

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TSS461C

4193G–AUTO–12/04

The Last Error Status Register (0x07) informs about the trouble encountered:

•

Failure cases:

–

Code viol (CV error bit)

–

Acknowledge error (ACKE error bit)

–

CRC error (FCSE error bit)

•

It should be noticed that contention is considered as normal CSMA/CD protocol

and, therefore, is not taken into account in failure cases. So, an “infinite” number of

attempts can be performed if bus contention occurs continuously.

There is only one retry counter for all channels. When the user writes the Max_Retries

value, all channels start their transmission with this parameter.

Rearbitrate

The purpose of rearbitrate feature is to postpone a channel already in transmission in

order to authorize an higher priority (see Section “Priority Among the Different Chan-

nels”) message to be transmit.

Typical Example

•

Max_retries = 1 (2 transmissions attempts).

•

If Ch8 is in a the retry loop and the user wants to transmit the Ch5 without waiting

the end of the loop, the user can use the rearbitrate command.

•

Then, the TSS461C will wait the end of the current transmission, reload the retries

counter and enable the Ch5 to transmit.

•

At the end of this transmission Ch5, either when the attempt is successful or either

when the exceeded retry count is reached, the retries counter is reloaded and the

transmission is activated for the Ch8 again.

Figure 25. Rearbitrate Example

VCC

EOF+IFS

Delay

stand-by

Delay

V iol

Viol

EOF+IFS: 8 + 4 Timeslots

Delay Viol: 12 Timeslots

* (not seen by application means no IT generation)

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