Datasheet

DS21352/DS21552
57 of 137
RS1 TO RS12: RECEIVE SIGNALING REGISTERS (Address=60 to 6B Hex)
(MSB) (LSB)
A(8) A(7) A(6) A(5) A(4) A(3) A(2) A(1) RS1 (60)
A(16) A(15) A(14) A(13) A(12) A(11) A(10) A(9) RS2 (61)
A(24) A(23) A(22) A(21) A(20) A(19) A(18) A(17) RS3 (62)
B(8) B(7) B(6) B(5) B(4) B(3) B(2) B(1) RS4 (63)
B(16) B(15) B(14) B(13) B(12) B(11) B(10) B(9) RS5 (64)
B(24) B(23) B(22) B(21) B(20) B(19) B(18) B(17) RS6 (65)
A/C(8) A/C(7) A/C(6) A/C(5) A/C(4) A/C(3) A/C(2) A/C(1) RS7 (66)
A/C(16) A/C(15) A/C(14) A/C(13) A/C(12) A/C(11) A/C(10) A/C(9) RS8 (67)
A/C(24) A/C(23) A/C(22) A/C(21) A/C(20) A/C(19) A/C(18) A/C(17) RS9 (68)
B/D(8) B/D(7) B/D(6) B/D(5) B/D(4) B/D(3) B/D(2) B/D(1) RS10 (69)
B/D(16) B/D(15) B/D(14) B/D(13) B/D(12) B/D(11) B/D(10) B/D(9) RS11 (6A)
B/D(24) B/D(23) B/D(22) B/D(21) B/D(20) B/D(19) B/D(18) B/D(17) RS12 (6B)
SYMBOL POSITION NAME AND DESCRIPTION
D(24) RS12.7
Signaling Bit D in Channel 24
A(1) RS1.0
Signaling Bit A in Channel 1
Each Receive Signaling Register (RS1 to RS12) reports the incoming robbed bit signaling from eight
DS0 channels. In the ESF framing mode, there can be up to four signaling bits per channel (A, B, C, and
D). In the D4 framing mode, there are only two signaling bits per channel (A and B). In the D4 framing
mode, the framer will replace the C and D signaling bit positions with the A and B signaling bits from the
previous multiframe. Hence, whether the framer is operated in either framing mode, the user needs only
to retrieve the signaling bits every 3 ms. The bits in the Receive Signaling Registers are updated on
multiframe boundaries so the user can utilize the Receive Multiframe Interrupt in the Receive Status
Register 2 (SR2.7) to know when to retrieve the signaling bits. The Receive Signaling Registers are
frozen and not updated during a loss of sync condition (SR1.0=1). They will contain the most recent
signaling information before the “OOF” occurred. The signaling data reported in RS1 to RS12 is also
available at the RSIG and RSER pins.
A change in the signaling bits from one multiframe to the next will cause the RSC status bit (SR2.0) to be
set. The user can enable the INT pin to toggle low upon detection of a change in signaling by setting the
IMR2.0 bit. Once a signaling change has been detected, the user has at least 2.75 ms to read the data out
of the RS1 to RS12 registers before the data will be lost.