COM20051I Datasheet, PDF (29/74 Pages) SMSC Corporation – Integrated Microcontroller and ARCNET (ANSI 878.1) Interface

Table 8 - Diagnostic Status Register
BIT BIT NAME SYMBOL
DESCRIPTION
7 My
MY-
This bit, if high, indicates that a past reconfiguration was
Reconfiguration RECON caused by this node. It is set when the Lost Token Timer
times out, and is typically read following an interrupt
caused by RECON. Refer to the Improved Diagnostics
section for further detail.
6 Duplicate ID 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. The
EOT character and the 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
off. When the device is on line it 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.
5 Receive
RCVACT This bit, if high, indicates that data activity (logic "1") was
Activity
detected on the RXIN pin of the device. Refer to the
Improved Diagnostics section for further detail.
4
Token Seen
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.
3 Excessive NAK 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.
2 Tentative ID
1 New Next ID
1,0 (Reserved)
TENTID
NEW
NXTID
This bit, if high, indicates that a response to a token whose
DID matches the value in the Tentative ID Register has
occurred. In addition, the EOT character is checked. 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.
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.
SMSC DS – COM20051I
Page 29
Rev. 03/27/2000