dp83261 National Semiconductor Corporation, dp83261 Datasheet - Page 59

• Manufacturer Part Number: dp83261
• Description: Bmac Device Fddi Media Access Controller
• Manufacturer: National Semiconductor Corporation

6 0 Control Information
Valid Transmission Time (TVX)
The Valid Transmission Timer (TVX) is used to increase the responsiveness of the ring to errors that cause ring recovery The
TVX value denotes the maximum time in which a valid frame or token should be seen by this station TVX is stored as a 4-bit
value that is expanded to a binary exponential value Bits 7 – 4 are ignored during write operations and read as Zero
TVX has a maximum value of 1 34 seconds with a threshold of 40 96 X 2
One) TVX is set to the value of 6h which corresponds to 2 62 ms the default by the FDDI MAC Standard
ACCESS RULES
TVX
Address
97h
Zero
D7
Always
Read
Zero
D6
(Continued)
Stop Mode
Zero
TVX(0 – 3)
D5
Write
A
B
C
D
0
1
2
3
4
5
6
7
8
9
E
F
Zero
D4
59
163 84 ms
327 68 ms
655 36 ms
1 3107 ms
2 6214 ms (default)
5 2429 ms
10 486 ms
20 972 ms
41 943 ms
83 886 ms
167 77 ms
335 54 ms
671 09 ms
1 3422s
40 96 ms
81 92 ms
TVX(3)
Time
D3
TVX
ms On a Master Reset (Function MARST is set to
TVX(2)
D2
TVX(1)
D1
TVX(0)
D0