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HDLC CONTROLLER
31
30 29 28 27 26 25
D
D
D
D
P
P
T
T
L
L
x
x
L
L
N
F
T
O
O
D
M
M
[3:0] Rx remaining bytes (RxRB)
At 1-word boundary:
0000 = Valid data byte is 1
0001 = Valid data byte is 2
0010 = Valid data byte is 3
0011 = Valid data byte is 4
[4] Tx frame complete (TxFC)
0 = Normal operation
1 = Automatically set; if two conditions are met:
1) Tx FIFO is empty.
[5] Tx FIFO available (TxFA)
0 = Tx FIFO is not available.
1 = Tx FIFO is available. (that is, the data to be transmitted can now be
loaded into the Tx FIFO.)
[6] Tx clear-to send (TxCTS)
0 = Level at the nCTS input pin is High.
1 = Level at the nCTS input pin is Low.
[7] Tx stored clear-to-send (TxSCTS)
0 = Normal operation
1 = A transition occured at the nCTS input. (This transition can be used to
trigger an interrupt.)
[8] Tx underrun (TxU)
0 = Normal operation
1 = The transmitter ran out of data during transmission.
[9] Rx FIFO available (RxFA)
0 = Normal operation
1 = Data is available in the RxFIFO.
[10] Tx Frame Good (TxFG)
0 = Normal operation
1 = Tx Data sent well
[11] Rx flag detected (RxFD)
0 = Normal operation
1 = This bit is set, when the last bit of the flag sequence is received.
[12] Rx data-carrier-detected (RxDCD)
0 = nDCD input pin is High
1 = nDCD input pin is Low
[13] Rx stored data-carrier-detected (RxSDCD)
0 = Normal operation
1 = When a transition of the nDCD input occurs, this bit is set.
[14] Rx frame valid (RxFV)
0 = Normal operation
1 = The last data byte if a frame is transferred into the last location of RxFIFO.
[15] Rx idle (RxIDLE)
0 = Normal operation
1 = A minimum 15 consecutive 1's have been received.
8-40
24
23 22
21
20 19
D
D
R
D
R
R
R
x
T
x
x
x
I
x
O
N
F
E
A
V
O
D
R
B
R
T
At 4-word boundary:
0000 = Valid data byte is 1
.
.
1111 = Valid data byte is 16
2) An abort or a closing flag is transmitted.
Figure 8-15. HDLC Status Register
18 17 16
15 14
13 12 11
R
R
R
R
R
R
R
R
x
x
x
x
x
x
x
x
N
C
A
I
F
S
D
F
O
R
B
D
V
D
C
D
C
T
L
C
D
E
E
D
10 9
8 7 6
5
4
3
R
T
T
T
T
T
T
x
x
x
x
x
x
x
F
F
U
S
C
F
F
A
A
G
C
T
C
T
S
S
S3C2500B
0
R
x
R
B
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