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3.2.4 Transmit Status Register (TX_STATUS)
The transmit status register holds the transmit FSM state, LATE_CT,
RING_OPERATIONAL, and the state of the frame transmission machine. The NP can
read the transmit status register at any time but can never write to this register. lt is cleared
on power-up reset and by a MAC_RESET.
15
TX_FSM_STATE
7
6
FLD_SEQ_STATE(CONT'D)
TX_FSM_STATE—Transmit Finite State Machine State
These bits indicate the state of the overall operation of the MAC transmitter FSM.
0000 = Tx_Idle (T0)—Constantly transmit idle symbols
0001 = Tx_Data (T2)—Transmit data frames
0010 = Tx_Token (T3)—Transmit token
0011 = Tx_Void—Transmit special void frame
0100 = Tx_Repeat (T1)—Repeat incoming frame/token
0101 = Reserved
0110 = Tx_Beacon (T5)—Constantly transmit beacon frames
0111 = Tx_Claim (T4)—Constantly transmit claim frames
1000 = Reserved
1001 = Reserved
1010 = Reserved
1011 = Reserved
1100 = FDX_Data—Transmit FSI FDX data frame
1101 = Reserved
1110 = Reserved
1111 = Tx_Off—MAC is turned off
RING_OP—Ring Operational
This value indicates whether or not the ring is operational.
0 = RING_OPERATIONAL is cleared by the transmit FSM, indicating that the ring is
not operational.
1 = RING_OPERATIONAL is set, indicating that the ring is operational.
PURGING—Purging
This bit indicates the current value of purging.
1 = Transmitter is currently purging the ring. The transmitter will not enter repeat
mode (Tx_Repeat state). This bit is set upon sending the end of the first of the
two special void frames sent as a result of RING_PURGE being set.
0 = A special void frame is returned or a nonduplicate token is returned,
RING_OPERATIONAL becomes zero, the transmitter enters the FDX states, or
the MAC is turned off (MAC_ON = 0). This bit is not cleared (stripping continues)
if a duplicate token is received (i.e., a token received while transmitting).
FLD_SEQ_STATE—Field Sequence State
MOTOROLA
12
RING_OP
5
FLD_CNT_STATE
MC68838 USER'S MANUAL
11
10
PURGING
3
2
9
8
FLD_SEQ_STATE
0
LATE_CT
3- 15
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