DS21Q55 Maxim Integrated Products, DS21Q55 Datasheet - Page 173

• Manufacturer Part Number: DS21Q55
• Description: IC TXRX QUAD T1/E1/J1 SCT 256BGA
• Manufacturer: Maxim Integrated Products

Specifications of DS21Q55

• Function: Transceiver
• Interface: E1, J1, T1
• Number Of Circuits: 4
• Voltage - Supply: 3.14 V ~ 3.47 V
• Current - Supply: 75mA
• Operating Temperature: 0°C ~ 70°C
• Mounting Type: Surface Mount
• Package / Case: 256-BGA
• Includes: BERT Generator and Detector, Dual HDLC Controllers
• Lead Free Status / RoHS Status: Contains lead / RoHS non-compliant
• Power (watts): -

DS21Q55 Quad T1/E1/J1 Transceiver
24.
BERT FUNCTION
The BERT block can generate and detect pseudorandom and repeating bit patterns. It is used to test and
stress data communication links, and it is capable of generating and detecting the following patterns:
§ The pseudorandom patterns 2E7, 2E11, 2E15, 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
The BERT receiver has a 32-bit bit counter and a 24-bit error counter. The BERT receiver reports three
events: a change in receive synchronizer status, a bit error being detected, and if either the bit counter or
the error counter overflows. Each of these events can be masked within the BERT function through the
BERT control register 1 (BC1). If the software detects that the BERT has reported an event, then the
software must read the BERT information register (BIR) to determine which event(s) has occurred. To
activate the BERT block, the host must configure the BERT mux through the BIC register.
24.1 Status
SR9 contains the status information on the BERT function. The host can be alerted through this register
when there is a BERT change-of-state. A major change-of-state is defined as either a change in the
receive synchronization (i.e., the BERT has gone into or out of receive synchronization), a bit error has
been detected, or an overflow has occurred in either the bit counter or the error counter. The host must
read status register 9 (SR9) to determine the change-of-state.
24.2 Mapping
The BERT function can be assigned to the network direction or backplane direction through the direction
control bit in the BIC register (BIC.1). See
Figure 24-1
and
Figure
24-2. The BERT also can be assigned
on a per-channel basis. The BERT transmit control selector (BTCS) and BERT receive control selector
(BRCS) bits of the per-channel pointer register (PCPR) are used to map the BERT function into time slots
of the transmit and receive data streams. In T1 mode, the user can enable mapping into the F-bit position
for the transmit and receive directions through the RFUS and TFUS bits in the BERT interface control
(BIC) register.
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