COM20020I_0609 Datasheet, PDF (14/69 Pages) SMSC Corporation – 5Mbps ARCNET (ANSI 878.1) Controller with 2K x 8 On-Chip RAM

5Mbps ARCNET (ANSI 878.1) Controller with 2K x 8 On-Chip RAM
ƒ N data bytes where COUNT = 256-N (or 512-N for a long packet)
ƒ Two CRC (Cyclic Redundancy Check) characters. The CRC polynomial used is: X¹⁶ + X¹⁵ + X² + 1.
ALERT
SOH SID DID DID COUNT data
BURST
data CRC CRC
Acknowledgements
An Acknowledgement is used to acknowledge reception of a packet or as an affirmative response to FREE BUFFER
ENQUIRIES and is sent by the following sequence:
ƒ An ALERT BURST
ƒ An ACK (ACKnowledgement--ASCII code 86H) character
ALERT BURST
ACK
Negative Acknowledgements
A Negative Acknowledgement is used as a negative response to FREE BUFFER ENQUIRIES and is sent by the
following sequence:
ƒ An ALERT BURST
ƒ A NAK (Negative Acknowledgement--ASCII code 15H) character
ALERT BURST
NAK
SMSC COM20020I 3.3V Rev.E
Page 14
DATASHEET
Revision 09-11-06