ds21ft40 Maxim Integrated Products, Inc., ds21ft40 Datasheet - Page 25

• Manufacturer Part Number: ds21ft40
• Description: Ds21ft40 Four X Three 12 Channel E1 Framer
• Manufacturer: Maxim Integrated Products, Inc.

Power–Up Sequence
The DS21FT40 does not automatically clear its register space on power–up. After the supplies are stable,
each of the four framer’s register space should be configured for operation by writing to all of the internal
registers. This includes setting the Test and all unused registers to 00Hex.
Finally, after the TSYSCLK and RSYSCLK inputs are stable, the ESR bit should be toggled from a zero
to a one (this step can be skipped if the elastic stores are disabled).
IDR: DEVICE IDENTIFICATION REGISTER (Address=0F Hex)
RCR1: RECEIVE CONTROL REGISTER 1 (Address=10 Hex)
1. Clear each quad framer’s register space by writing 00H to addresses 00H through 0BFH.
2. Program required registers to achieve desired operating mode.
This can be accomplished using a two-pass approach on each quad framer within the DS21FT40.
(MSB)
RSMF
(MSB)
T1E1
SYMBOLS
SYMBOLS
RSMF
RSIO
T1E1
RSM
ID3
ID2
ID1
ID0
–
–
RSM
0
POSITION
POSITION
RCR1.7
RCR1.6
RCR1.5
RCR1.4
RCR1.3
IDR.3
IDR.1
IDR.2
IDR.0
IDR.7
RSIO
0
NAME AND DESCRIPTION
T1 or E1 Chip Determination Bit.
0=T1 chip
1=E1 chip
Chip Revision Bit 3. MSB of a decimal code that represents
the chip revision.
Chip Revision Bit 2.
Chip Revision Bit 1.
Chip Revision Bit 0. LSB of a decimal code that represents
the chip revision.
NAME AND DESCRIPTION
RSYNC Multiframe Function. Only used if the RSYNC pin
is programmed in the multiframe mode (RCR1.6=1).
0 = RSYNC outputs CAS multiframe boundaries
1 = RSYNC outputs CRC4 multiframe boundaries
RSYNC Mode Select.
0 = frame mode (see the timing in Section 18)
1 = multiframe mode (see the timing in Section 18)
RSYNC I/O Select. (note: this bit must be set to zero when
RCR2.1=0).
0 = RSYNC is an output (depends on RCR1.6)
1 = RSYNC is an input (only valid if elastic store enabled)
Not Assigned. Should be set to zero when written.
Not Assigned. Should be set to zero when written.
0
–
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ID3
–
FRC
ID2
SYNCE
ID1
RESYNC
(LSB)
(LSB)
DS21FT40
ID0