DS2196 datasheet(86/157 Pages) DALLAS

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DS2196

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15.

BERT FUNCTION

The BERT Block can generate and detect both pseudorandom and repeating bit patterns and it is used to

test and stress data communication links.

The BERT Block is capable of generating and detected 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 which 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 will report

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

via the BERT Control Register 1 (BC1). If the software detects that the BERT has reported an event has

occurred, 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 via the BIC register

(see Figure 15-1).

The BERT INTERRUPT REQUEST (BIRQ) status bit located at ISR.6 will be set to a 1 if there is a

major change of state in the BERT receiver. 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 the status bits of the BERT in the BERT Information Register (BIR) to determine the change of

state. The BIRQ bit will be cleared when read and will not be set again until the BERT has experienced

another change of state.

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