TNETX3150 datasheet(79/113 Pages) TI1

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TNETX3150/TNETX3150A

ThunderSWITCH™ 15-PORT 10-/100-MBIT/S ETHERNET™ SWITCH

SPWS027F – FEBRUARY 1997 – REVISED SEPTEMBER 1997

POST OFFICE BOX 655303

• DALLAS, TEXAS 75265

tertiary test access

The internal RAM access infers only that both DIO port and internal RAM structures are functioning correctly.

It does not provide information on the TNETX3150/TNETX3150A data paths (to and from the RAMS) during

normal frame operations or an indication of the control path functionality. To further assist with this, the proposed

tests are as follows:

• DRAM access — this test proves that the data path between FIFO and DRAM is functioning, along with

certain sections of the queue manager and FIFO logic operations.

• Frame forwarding — frame data is forwarded from one port to the next using a loop-back mode. This

builds on the previous tests, and tests that the data path to and from the protocol handlers and control

paths are operational. The number of ports that take part in forwarding is controlled using the VLAN

registers, allowing any number of ports to be tested in this mode. Single connections can be tested

allowing individual protocol-handler data paths-to-FIFO connections to be tested or multiple port testing

that allows reduced system test time.

external DRAM test access

Using the incremental test approach (after the FIFO is tested and verified), the data path to and control of the

external DRAM memory is verified.

DRAM writes are carried out by first constructing a buffer in the FIFO (64 bytes), and then initiating a buffer write

from the FIFO to the DRAM. The buffer is transferred like a normal buffer transfer in a 17-write DRAM burst.

The forward pointer field is mapped to the DRAM data register, and the flag data fields are mapped to the DRAM

flag register.

Reading from the DRAM performs a buffer transfer to the FIFO from which individual bytes can be read (and

tested) through the DIO interface. The flag bytes and forward-pointer bytes are transferred from the DRAM to

the DRAM-data and DRAM-flag registers for reading.

The buffer transfer mechanism, when operated in DRAM test access mode, does not check the flag status. No

actions are performed, depending on the status of the flags. The transfer is a test data transfer, with no attempt

made to comprehend flag contents.

After completion of the DRAM testing, the TNETX3150/TNETX3150A should be reset before normal switching

activity is resumed. This ensures that the TNETX3150/TNETX3150A is returned to a defined state before

normal functionality is resumed. This mechanism is primarily intended for DRAM testing and is not a part of a

breakpoint/debug mechanism.

For more information refer to the

test register section.

TNETX3150 数据表(PDF) 79 Page - Texas Instruments

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