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Motorola MC68838 User Manual page 41

Media access controller
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This bit is set when a claim frame is received with SA = my long address register and
the receiver FSM signals HIGHER_CLAIM or LOWER_CLAIM, indicating that T_Bid <>
PURGE_ERR—Purge Error
This bit indicates that an error has been detected in the purging process. Purge error is
set when the MAC receives a token and the MAC is not transmitting data, void, or token
frames and is actively purging the ring while awaiting the return of one of its special void
frames. A token received while the MAC is transmitting (i.e., a duplicate token) will not
cause this interrupt bit to be set, nor terminate the purging process. On the other hand,
such a token will invoke the DUPL_TKN interrupt.
BRIDGE_STRP_ERR—Bridge Strip Error
This bit is set when the SENT_COUNT > 0 and a token is received when the transmitter
is not in any of the following states: Tx_Data, Tx_Void, or Tx_Token. This bit will not be
set if the MAC is transmitting and receives a token. That event is indicated by the
DUPL_TKN interrupt.
This bit is set when the MAC starts to issue a token as a result of winning the claim
process (i.e., upon receiving a MY_CLAIM while in the Tx_Claim state and no
MAC_Reset). Because of subsequent events, the MAC may not actually finish sending
the token.
NP_ERR—Node Processor Interface Error
This bit is set when the MAC detects an invalid NP read or write cycle. For example, this
bit is set when the NP attempts to read a nonexistent register address or when the NP
attempts to write either a read-only register or a READ/CNTRL WRITE register while the
MAC FSMs are running (i.e., MAC_ON = 1).
SI_ERR—System Interface Error
This bit is set when the MAC detects an error in the MAC-FSI interface. For example,
this bit is set when the TPRITY signal indicates a parity error and TXPARITY_ON is
enabled or when the TXCTLx lines do not progress through their required cycle.
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