TSS463-AA ATMEL Corporation, TSS463-AA Datasheet - Page 47

• Manufacturer Part Number: TSS463-AA
• Description: Van (ISO Standard 11519-3) Datalink Controller With Serial Interface.
• Manufacturer: ATMEL Corporation

Priority Among the
Different Channels
Retries, Rearbitrate and
Abort
4205A–AUTO–03/03
The priority handling on the VAN bus itself is already explained in the Line interface sec-
tion. The priorities for the messages in the TSS463AA is however slightly different.
For instance, it’s possible that an identifier matches two or more of the identifiers pro-
grammed into the registers. In this case, it is the lowest identifier number that has
priority. i.e., if both identifier 5 and 10 match the identifier received, it is the identifier 5
that will receive the message.
However, since the identifier 5 will become an inactive message when it has received
the frame, the next time the same identifier is seen on the bus, the corresponding data
will be received by identifier 10.
The same is valid for messages to be transmitted, i.e. if two or more messages are
ready to be transmitted, it is the one with the lowest identifier number that will get
priority.
Retries and rearbitrate commands are located, respectively, in the Transmit Control
Register and in the Command Register. An abort command is located in each channel
register set, in the Message Length and Status Register (base_address + 0x03). These
three commands are available only when the TSS463AA is a producer.
Figure 30. Transmit Function
Retry Counter
Decrement
Current Ch.
Disable of
Abort
Yes
Yes
(EOF+IFS= 12 Timeslots)
Load ”Max - Retries”
and Wait for the End
Select the Lowest
Wait for Bus Free
Ch. Number and
on Current Ch. ?
Transmit Frame
Retry Needed ?
Abort Activated
Abort Required
Ch. Enabled in
on Current Ch.
Xmit Mode ?
Rearbitrate?
Activate
Yes
No
no
No
No
Rearbitrate
TSS463-AA
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