TLK111_14 Datasheet, PDF (19/110 Pages) Texas Instruments – PHYTER® Industrial Temperature 10/100Mbs Ethernet Physical Layer Transceiver

TLK111
www.ti.com
SLLSEF8B – AUGUST 2013 – REVISED JANUARY 2014
3.12 BIST
The device incorporates an internal PRBS Built-in Self Test (BIST) circuit to accommodate in-circuit
testing or diagnostics. The BIST circuit can be used to test the integrity of the transmit and receive data
paths. The BIST can be performed using both internal loopback (digital or analog) or external loopback
using a cable fixture. The BIST simulates pseudo-random data transfer scenarios in format of real packets
and Inter-Packet Gap (IPG) on the lines. The BIST allows full control of the packet lengths and of the IPG.
The BIST is implemented with independent transmit and receive paths, with the transmit block generating
a continuous stream of a pseudo-random sequence. The device generates a 15-bit pseudo-random
sequence for the BIST. The received data is compared to the generated pseudo-random data by the BIST
Linear Feedback Shift Register (LFSR) to determine the BIST pass/fail status. The number of error bytes
that the PRBS checker received is stored in the BICSR1 register (0x001Bh). The status of whether the
PRBS checker is locked to the incoming receive bit stream, whether the PRBS has lost sync, and whether
the packet generator is busy, can be read from the BISCR register (0x0016h). While the lock and sync
indications are required to identify the beginning of proper data reception, for any link failures or data
corruption, the best indication is the contents of the the error counter in the BICSR1 register (0x001Bh).
The PRBS test can be put in a continuous mode or single mode by using bit 14 of the BISCR register
(0x0016h). In continuous mode, when one of the PRBS counters reaches the maximum value, the counter
starts counting from zero again. In single mode, when the PRBS counter reaches its maximum value, the
PRBS checker stops counting.
The device allows the user to control the length of the PRBS packet. By programming the BICSR2 register
(0x001Ch) one can set the length of the PRBS packet. There is also an option to generate a single-packet
transmission of two types, 64 and 1518 bytes, through register bit 13 of the BISCR register (0x0016h).
The single generated packet is composed of a constant data.
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Hardware Configuration
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