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FALC
56
PEF 2256 H/E
Functional Description T1/J1
User’s Manual
Hardware Description
157
DS1.1, 2003-10-23
interface automatically. However, received data is switched through transparently if
bit FMR2.DAIS is set.
Automatic clock source switching
In slave mode (LIM0.MAS = 0) the DCO-R synchronizes on the recovered route
clock. In case of loss-of-signal (LOS) the DCO-R switches to master mode
automatically. If bit CMR1.DCS is set, automatic switching from RCLK to SYNC is
disabled.
Automatic freeze signaling:
Updating of the received signaling information is controlled by the freeze signaling
status. The freeze signaling status is activated automatically, if a loss-of-signal or a
loss of multiframe alignment or a receive slip occurs. The internal signaling buffer
RS(12:1) is frozen. Optionally automatic freeze signaling is disabled by setting bit
SIC3.DAF = 1.
5.3.3
The FALC
56 offers six error counters where each of them has a length of 16 bit. They
record code violations, framing bit errors, CRC6 bit errors, errored blocks and the
number of received multiframes in asynchronous state or the Changes Of Frame
Alignment (COFA). Counting of the multiframes in asynchronous state and of the COFA
parameter is done in a 6/2-bit counter. Each of the error counters is buffered. Buffer
update is done in two modes:
One-second accumulation
On demand using handshake with writing to the DEC register.
In the one-second mode an internal/external one-second timer updates these buffers
and resets the counter to accumulate the error events in the next one-second period.
The error counter cannot overflow. Error events occurring during error counter reset are
not be lost.
Error Counters
5.3.4
The FALC
56 supports the error performance monitoring by detecting the following
alarms or error events in the received data:
framing errors, CRC errors, code violations, loss of frame alignment, loss-of-signal,
alarm indication signal, receive and transmit slips.
With a programmable interrupt mask register ESM all these alarms or error events can
generate an Errored Second Interrupt (ISR3.ES) if enabled.
Errored Second
5.3.5
One-Second Timer
Additionally a one-second timer interrupt can be generated internally to indicate that the
enabled alarm status bits or the error counters have to be checked. The one-second
timer signal is output on port SEC/FSC (GPC1.CSFP1/0). Optionally synchronization to