COM20020D Datasheet, PDF (29/72 Pages) SMSC Corporation – ULANC Revision D Universal Local Area Network Controller with 2K x 8 On-Board RAM

BIT
BIT NAME
7 My
Reconfiguration
6 Duplicate ID
5 Receive
Activity
4 Token Seen
3 Excessive NAK
2 Tentative ID
1 New Next ID
1,0 (Reserved)
Table 5 - Diagnostic Status Register
SYMBOL
DESCRIPTION
MY-
RECON
This bit, if high, indicates that a past reconfiguration was caused by this
node. It is set when the Lost Token Timer times out, and should be
typically read following an interrupt caused by RECON. Refer to the
Improved Diagnostics section for further detail.
DUPID
This bit, if high, indicates that the value in the Node ID Register
matches both Destination ID characters of the token and a response to
this token has occurred. Trailing zero's are also verified. A logic "1" on
this bit indicates a duplicate Node ID, thus the user should write a new
value into the Node ID Register. This bit is only useful for duplicate ID
detection when the device is off line, that is, when the transmitter is
disabled. When the device is on line this bit will be set every time the
device gets the token. This bit is reset automatically upon reading the
Diagnostic Status Register. Refer to the Improved Diagnostics section
for further detail.
RCVACT
This bit, if high, indicates that data activity (logic "1") was detected on
the RXIN pin of the device. Refer to the Improved Diagnostics section
for further detail.
TOKEN
This bit, if high, indicates that a token has been seen on the network,
sent by a node other than this one. Refer to the Improved Diagnostic
section for further detail.
EXCNAK
This bit, if high, indicates that either 128 or 4 Negative
Acknowledgements have occurred in response to the Free Buffer
Enquiry. This bit is cleared upon the "POR Clear Flags" command.
Reading the Diagnostic Status Register does not clear this bit. This bit,
when set, will cause an interrupt if the corresponding bit in the IMR is
also set. Refer to the Improved Diagnostics section for further detail.
TENTID
This bit, if high, indicates that a response to a token whose DID
matches the value in the Tentative ID Register has occurred. The
second DID and the trailing zero's are not checked. Since each node
sees every token passed around the network, this feature can be used
with the device on-line in order to build and update a network map.
Refer to the Improved Diagnostics section for further detail.
NEW
NXTID
This bit, if high, indicates that the Next ID Register has been updated
and that a node has either joined or left the network. Reading the
Diagnostic Status Register does not clear this bit. This bit, when set,
will cause an interrupt if the corresponding bit in the IMR is also set.
The bit is cleared by reading the Next ID Register.
These bits are undefined.
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