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DS21354 & DS21554
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The SR1, SR2, and HSR registers have the unique ability to initiate a hardware interrupt via the INT*
output pin. Each of the alarms and events in the SR1, SR2, and HSR can be either masked or unmasked
from the interrupt pin via the Interrupt Mask Register 1 (IMR1), Interrupt Mask Register 2 (IMR2), and
HDLC Interrupt Mask Register (HIMR) respectively. The HIMR register is covered in Section 15.
The interrupts caused by alarms in SR1 (namely RUA1, RRA, RCL, and RLOS) act differently than the
interrupts caused by events in SR1 and SR2 (namely RSA1, RDMA, RSA0, RSLIP, RMF, TMF, SEC,
TAF, LOTC, RCMF, and TSLIP). The alarm caused interrupts will force the INT* pin low whenever the
alarm changes state (i.e., the alarm goes active or inactive according to the set/clear criteria in Table 7-1).
The INT* pin will be allowed to return high (if no other interrupts are present) when the user reads the
alarm bit that caused the interrupt to occur even if the alarm is still present.
The event caused interrupts will force the INT* pin low when the event occurs. The INT* pin will be
allowed to return high (if no other interrupts are present) when the user reads the event bit that caused the
interrupt to occur.
RIR: RECEIVE INFORMATION REGISTER
(Address=08 Hex)
(MSB)
(LSB)
TESF
TESE
JALT
RESF
RESE
CRCRC
FASRC
CASRC
SYMBOL
POSITION
NAME AND DESCRIPTION
TESF
RIR.7
Transmit Side Elastic Store Full.
Set when the transmit side elastic store
buffer fills and a frame is deleted.
TESE
RIR.6
Transmit Side Elastic Store Empty.
Set when the transmit side elastic
store buffer empties and a frame is repeated.
JALT
RIR.5
Jitter Attenuator Limit Trip.
Set when the jitter attenuator FIFO reaches
to within 4–bits of its limit; useful for debugging jitter attenuation
operation.
RESF
RIR.4
Receive Side Elastic Store Full.
Set when the receive side elastic store
buffer fills and a frame is deleted.
RESE
RIR.3
Receive Side Elastic Store Empty.
Set when the receive side elastic store
buffer empties and a frame is repeated.
CRCRC
RIR.2
CRC Resync Criteria Met.
Set when 915/1000 code words are received
in error.
FASRC
RIR.1
FAS Resync Criteria Met.
Set when 3 consecutive FAS words are
received in error.
CASRC
RIR.0
CAS Resync Criteria Met.
Set when 2 consecutive CAS MF alignment
words are received in error.