Hi
You can use, as wrote alledauser, a T1/E1 framer after a line interface component.
Generaly , a framer include registers (counters) for :
- Framing errors F bit (T1) or TS0 (E1).
- Line code violation.
- CRC6 (T1) or CRC4 (E1) errors.
- Loss of frame alignment.
- Changes in frame alignment.
With a µC like 8031, you only need to init correctely the framer and peridicaly read each counter.
Be sure your line interface includes a impedance selection for T1 (100 ohms) and E1 (75 or 100 ohms). You can find a lot of design apps from LEVEL ONE on this subject :
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http://www.intel.com/design/network/products/WAN/applnots/24915901.pdf
Some framers also include the line interface (LIU)
Dallas DS2155 LIU + PLL + Framer + 2*HDLC :
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Infineon FALC56 (PEB2256) LIU + PLL + Framer + 3*HDLC :
http://www.infineon.com/cgi/ecrm.dll/ecrm/scripts/prod_ov.jsp?oid=13588&cat_oid=-10080
PMC Sierra COMET (PM4351) LIU + Framer + 3*HDLC
http://www.pmc-sierra.com/products/details/pm4351/index.html
Zarlink MT9076B LIU + PLL + Framer + 3*HDLC :
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