COM20020ILJP datasheet(31/72 Pages) MICROCHIP

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5Mbps ARCNET (ANSI 878.1) Controller with 2K x 8 On-Chip RAM

Datasheet

SMSC COM20020I Rev D

Page 31

Revision 12-05-06

DATASHEET

Table 6.3 - Status Register

BIT

BIT NAME

SYMBOL

DESCRIPTION

Receiver

Inhibited

This bit, if high, indicates that the receiver is not enabled because either

an "Enable Receive to Page fnn" command was never issued, or a packet

has been deposited into the RAM buffer page fnn as specified by the last

"Enable Receive to Page fnn" command. No messages will be received

until this command is issued, and once the message has been received,

the RI bit is set, thereby inhibiting the receiver. The RI bit is cleared by

issuing an "Enable Receive to Page fnn" command. This bit, when set,

will cause an interrupt if the corresponding bit of the Interrupt Mask

attempts to send a packet to this station, this station will send a NAK.

6,5

(Reserved)

These bits are undefined.

Power On Reset

POR

This bit, if high, indicates that the COM20020ID has been reset by either a

software reset, a hardware reset, or writing 00H to the Node ID Register.

The POR bit is cleared by the "Clear Flags" command.

Test

TEST

This bit is intended for test and diagnostic purposes. It is a logic "0" under

normal operating conditions.

Reconfiguration

RECON

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

the RXIN pin was idle for 41

μS. 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

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.

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