dp83251 National Semiconductor Corporation, dp83251 Datasheet - Page 27

• Manufacturer Part Number: dp83251
• Description: Player Device Fddi Physical Layer Controller
• Manufacturer: National Semiconductor Corporation

D0 D1
D2
5 0 Registers
CURRENT TRANSMIT STATE REGISTER (CTSR)
The Current Transmit State Register can program the Transmitter Block to internally generate and transmit Idle Master Halt
Quiet or user programmable symbol pairs in addition to the normal transmission of incoming PHY Request data The Smoother
and PHY Request Data Parity may also be enabled and disabled through this register
The Transmit Modes overwrite the Repeat Filter and Smoother outputs while the Injection Symbols overwrite the Transmit
Modes
During the reset process (i e RST
is set to 1) and the Reserved bit (b7) is set to 1 All other bits of this register are cleared (i e set to 0) during the reset process
ACCESS RULES
Bit
D7
RES
ADDRESS
04h
TM0 TM1
TM2
Symbol
D6
PRDPE
(Continued)
READ
Always
Transmit Mode
Data output port (TXD
D5
SE
e
GND) the Transmit Mode is set to Off (TM
TM2
0
0
0
0
1
1
1
1
WRITE
Conditional
k
D4
IC1
0 1 2
g
)
l
These bits select one of the 6 transmission modes for the PMD Request
TM1
0
0
1
1
0
0
1
1
D3
IC0
27
D2
TM2
TM0
Description
0
1
0
1
0
1
0
1
k
2 0
Active Transmit Mode (ATM) Normal
transmission of incoming PHY Request data
Idle Transmit Mode (ITM) Transmission of
Idle symbol pairs (11111 11111)
Off Transmit Mode (OTM) Transmission of
Quiet symbol pairs (00000 00000) and
deassertion of the FOTX Enable pin (TXE)
Reserved Reserved for future use Users
are discouraged from using this transmit
mode If selected however the transmitter
will generate Quiet symbol pairs (00000
00000)
Master Transmit Mode (MTM)
Transmission of Halt and Quiet symbol pairs
(00100 00000)
Halt Transmit Mode (HTM) Transmission of
Halt symbol pairs (00100 00100)
Quiet Transmit Mode (QTM) Transmission
of Quiet symbol pairs (00000 00000)
Reserved Reserved for future use Users
are discouraged from using this transmit
mode If selected however the transmitter
will generate Quiet symbol pairs (00000
00000)
D1
TM1
l
e
010) the Smoother is enabled (i e SE
D0
TM0