COM20019I-HT datasheet(28/65 Pages) SMSC

28 / 65 page

Low Cost ARCNET (ANSI 878.1) Controller with 2K x 8 On-Board RAM

Rev. 03-07-06

Page 28

SMSC COM20019I

DATASHEET

BIT

BIT NAME

SYMBOL

DESCRIPTION

Reconfiguration

RECON

This bit, if high, indicates that the Line Idle Timer has timed out

because the RXIN pin was idle for 656 S. The RECON bit is

cleared during a "Clear Flags" command. This bit, when set, will

cause an interrupt if the corresponding bit in the IMR is also set.

The interrupt service routine should consist of examining the

MYRECON bit of the Diagnostic Status Register to determine

whether there are consecutive reconfigurations caused by this

node.

Transmitter

Message

Acknowledged

TMA

This bit, if high, indicates that the packet transmitted as a result of

an "Enable Transmit from Page fnn" command has been

acknowledged. This bit should only be considered valid after the

TA bit (bit 0) is set. Broadcast messages are never

acknowledged. The TMA bit is cleared by issuing the "Enable

Transmit from Page fnn" command.

Transmitter

Available

This bit, if high, indicates that the transmitter is available for

transmitting. This bit is set when the last byte of scheduled

packet has been transmitted out, or upon execution of a "Disable

Transmitter" command. The TA bit is cleared by issuing the

"Enable Transmit from Page fnn" command after the node next

receives the token. This bit, when set, will cause an interrupt if

the corresponding bit in the IMR is also set.

Table 6.4 - Diagnostic Status Register

BIT

BIT NAME

SYMBOL

DESCRIPTION

Reconfiguration

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.

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. 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

detail.

Receive

Activity

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 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.

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.

COM20019I-HT Datasheet(PDF) 28 Page - SMSC Corporation

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