dp83251 National Semiconductor Corporation, dp83251 Datasheet - Page 15

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

4 0 Modes of Operation
The PLAYER device can operate in 4 basic modes RUN
STOP LOOPBACK and CASCADE
4 1 RUN MODE
RUN is the normal mode of operation
In this mode the PLAYER device is configured to be con-
nected to the media via the Fiber Optic Transmitter and
Receiver at the Serial Interface It is also connected to other
PLAYER device(s) and or BMAC device(s) via the Port A
and Port B Interfaces
While operating in the Run mode the PLAYER device re-
ceives and transmits Line States (Quiet Halt Master Idle)
and frames (Active Line State)
4 2 STOP MODE
The PLAYER device operates in the STOP mode while it is
being initialized or configured
The PLAYER device is also reset to the STOP mode auto-
matically when the RST pin (pin 71 on the DP83251 and pin
111 on the DP83255) is set to ground
When in STOP mode the PLAYER device performs the fol-
lowing functions
4 3 LOOPBACK MODE
The PLAYER device provides three types of loopback tests
Configuration Switch Loopback Internal Loopback and Ex-
ternal Loopback These Loopback modes can be used to
test different portions of the device
4 3 1 Configuration Switch Loopback
The Configuration Switch Loopback can be used to test the
data paths of the BMAC device(s) that are connected to the
PLAYER device before transmitting and receiving data
through the network
In the Configuration Switch Loopback mode the PLAYER
device performs the following functions
See Figure 4-1a and 4-1b for block diagrams











Resets the Repeat Filter
Resets the Smoother
Resets the Receiver Block Line State Counters
Flushes the Elasticity Buffer
Forces Line State Unknown in the Receiver Block
Outputs LSU symbol pairs (0 1 0011 1010) through
the PHY Data Indicate pins (AIP AIC AID
BIC BID
Outputs Quiet symbol pairs through the PMD Data Re-
quest pins (TXD
Resets all Control Bus register contents to zero or de-
fault values
Selects Port A PHY Request Data Port B PHY Request
Data or PHY Invalid to connect to Port A PHY Indicate
Data via the A IND Mux
Selects Port A PHY Request Data Port B PHY Request
Data or PHY Invalid to connect to Port B PHY Indicate
Data via the B IND Mux
Connects data from the Receiver Block to the Transmit-
ter Block via the Transmitter Mux (The PLAYER device
is repeating incoming data from the media in the Configu-
ration Switch Loopback mode )
k
7 0
l
)
g
)
k
7 0
l
BIP
15
FIGURE 4-1b Configuration Switch
FIGURE 4-1a Configuration Switch
Loopback for DP83255
Loopback for DP83251
FIGURE 4-1
TL F 10386 – 42
TL F 10386 – 43