DS26514 4-Port T1/E1/J1 Transceiver
19-5856; Rev 4; 5/11
101 of 305
BERT Status Interrupt Mask Register
1405h
BERT interrupt mask.
Note: The addresses shown above are for Framer 1.
The BERT block can generate and detect the following patterns:
The pseudorandom patterns 2E7-1, 2E9-1, 2E11-1, 2E15-1, and QRSS.
A repetitive pattern from 1 to 32 bits in length.
Alternating (16-bit) words that flip every 1 to 256 words.
Daly pattern (Modified 55 Octet pattern), 55 Octet pattern
The BERT function must be enabled and configured in the
TXPC and
RXPC registers for each port. The BERT can
then be assigned on a per-channel basis for both the transmitter and receiver, using the special per-channel
function in the
TBPCS1-4 and
RBCS1-4 registers. Individual bit positions within the channels can be suppressed
with the
TBPBS and
RBPBS registers. Using combinations of these functions, the BERT pattern can be transmitted
and/or received in single or across multiple DS0s, contiguous or broken. Transmit and receive bandwidth
assignments are independent of each other.
The BERT receiver has a 32-bit bit counter and a 24-bit error counter. The BERT receiver can generate interrupts
on: a change in receive-synchronizer status, receive all zeros, receive all ones, error counter overflow, bit counter
overflow, and bit error detection. Interrupts from each of these events can be masked within the BERT function via
the BERT Status Interrupt Mask Register
(BSIM). If the software detects that the BERT has reported an event, then
the software must read the BERT Latched Status Register
(BSR) to determine which event(s) has occurred.
Beginning with die revision B1, the DS26514 has a new set of BERT registers to complement the original registers.
These are located at 1400 hex. Additional features were added to support the 55 Octet Pattern and the ability to
byte-align to the DS0 timeslot. In addition, a new set of status registers was added that is intended to replace the
original status registers. The user now has the option to use either set of status registers, but it is recommended
that he/she use the new ones as they are more complete and easier to use. A BERT real-time status register
(BRSR) was added to provide better visibility of the status of the BERT.
9.13.1 BERT Repetitive Pattern Set
These registers must be properly loaded for the BERT to generate and synchronize to a repetitive pattern, a
pseudorandom pattern, alternating word pattern, or a Daly pattern. For a repetitive pattern that is fewer than 32
bits, the pattern should be repeated so that all 32 bits are used to describe the pattern. For example, if the pattern
was the repeating 5-bit pattern …01101… (where the rightmost bit is the one sent first and received first), then
BRP1 should be loaded with ADh, BRP2 with B5h, BRP3 with D6h, and BRP4 should be loaded with 5Ah. For a
pseudo-random pattern, all four registers should be loaded with all ones (i.e., FFh). For an alternating word pattern,
one word should be placed into BRP1 and BRP2 and the other word should be placed into BRP3 and BRP4. For
example, if the DDS stress pattern “7E” is to be described, the user would place 00h in BRP1, 00h in BRP2, 7Eh in
BRP3, and 7Eh in BRP4, and the alternating word counter would be set to 50 (decimal) to allow 100 bytes of 00h
followed by 100 bytes of 7Eh to be sent and received.
9.13.2 BERT Error Counter
Once BERT has achieved synchronization, this 24-bit counter will increment for each data bit received in error.
Toggling the LC control bit in BC1 can clear this counter. This counter saturates when full and will set the BECO
status bit in t
he BSR register.