
DS26522 Dual T1/E1/J1 Transceiver
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The Transmit FDL register (
T1TFDL) contains the facility data link (FDL) information that is to be inserted on a byte
basis into the outgoing T1 data stream. The LSB is transmitted first. In D4 mode, only the lower six bits are used.
8.9.5.4 Legacy T1 Receive FDL
It is recommended that the DS26522’s built-in BOC or HDLC controllers be used for most applications requiring
access to the FDL.
Table 8-16 shows the registers related to the receive FDL.
Table 8-16. Registers Related to T1 Receive FDL
REGISTER
FRAMER ADDRESSES
FUNCTION
062h
FDL code used to insert transmit
FDL.
Receive Latched Status Register 7(
RLS7)
096h
Receive FDL full bit is in this
register.
Receive Interrupt Mask Register 7
(RIM7)
0A6h
Mask bit for RFDL full.
Note: The addresses shown are for Framer 1. The address for Framer 2 can be calculated by adding 200 hex to the framer address.
In the receive section, the recovered FDL bits or Fs bits are shifted bit-by-bit into the Receive FDL register
(
T1RFDL). Since the
T1RFDL is 8 bits in length, it fills up every 2ms (8 x 250
s). The framer signals an external
controller that the buffer has filled via the
RLS7.2 bit. If enabled via
RIM7.2, the
INTB pin toggles low, indicating
that the buffer has filled and needs to be read. The user has 2ms to read this data before it is lost. Note that no
zero destuffing is applied for the data provided through the
T1RFDL register. The
T1RFDL reports the incoming
facility data link (FDL) or the incoming Fs bits. The LSB is received first. In D4 framing mode,
T1RFDL updates on
multiframe boundaries and reports only the Fs bits.
8.9.6
E1 Data Link
Table 8-17 shows the registers related to E1 data link.
Table 8-17. Registers Related to E1 Data Link
REGISTER
FRAMER
ADDRESSES
FUNCTION
E1 Receive Align Frame Register (
E1RAF)064h
Receive frame alignment register.
E1 Receive Non-Align Frame Register
065h
Receive non-frame alignment register.
E1 Received Si Bits of the Align Frame
066h
Receive Si bits of the frame alignment frames.
Received Si Bits of the Non-Align Frame
067h
Receive Si bits of the non-frame alignment
frames.
Received Sa4 to Sa8 Bits Register
069h, 06Ah,
06Bh, 06Ch,
06Dh
Receive Sa bits.
Transmit Align Frame Register
(E1TAF)164h
Transmit align frame register.
Transmit Non-Align Frame Register
165h
Transmit non-align frame register.
Transmit Si Bits of the Align Frame
166h
Transmit Si bits of the frame alignment frames.
Transmit Si Bits of the Non-Align Frame
167h
Transmit Si bits of the non-frame alignment
frames.
Transmit Sa4 to Sa8 Bits Register
169h, 16Ah,
16Bh, 16Ch,
16Dh
Transmit Sa4 to Sa8.
E1 Transmit Sa-Bit Control Register
114h
Transmit sources of Sa control.
Note: The addresses shown are for Framer 1. The address for Framer 2 can be calculated by adding 200 hex to the framer address.