Jak PIC napojit na ethernet

[Petr Simek]

On Mon, 20 Dec 2004, Jan Waclawek wrote:

> No, nechcem sa hadat ani nemam cas to hladat, ale to co popisujete je
> skor blizsie k PPP.
> Aj ked mozne to v urcitej variante je; "krasa" SLIPu spocivala prave v
> tom, ze nebol NIJAKO standardizovany, tudiz si ho kazdy napisal ako
> chcel. Potom sa to ad-hoc riesilo roznymi startup scriptami apod.
> Ale mam pocit, ze existoval aj "cisty" SLIP, t.j. len pripojim kabel a
> idem; v pripade "nejasnosti (strati byte) sa zamacha vhodnym
> handshakovym vodicom (DCD alebo DSR) (na tom obrazku boli naozaj nejake
> "extra" signaly zapojene).

SLIP je standartizovany docela dobre a jeden cas se velice pouzival pro
pripojeni dialupistu pod ruznymi OS. Existuje i verze CSLIP ale ta je
take standartizovana. Zacatek a konec paketu je nutne znat i bez extra
handshake vodicu - nekdy proste zadne nejsou. Na zaver pripojim vynatek
z prislusneho RFC popisujiciho SLIP:

   The SLIP protocol defines two special characters: END and ESC. END is
   octal 300 (decimal 192) and ESC is octal 333 (decimal 219) not to be
   confused with the ASCII ESCape character; for the purposes of this
   discussion, ESC will indicate the SLIP ESC character.  To send a
   packet, a SLIP host simply starts sending the data in the packet.  If
   a data byte is the same code as END character, a two byte sequence of
   ESC and octal 334 (decimal 220) is sent instead.  If it the same as
   an ESC character, an two byte sequence of ESC and octal 335 (decimal
   221) is sent instead.  When the last byte in the packet has been
   sent, an END character is then transmitted.

Takze presneji - urcuje se jen konec ramce-paketu (a ne i zacatek jak jsem
se mylne domnival) a jsou dva ridici znaky END a ESC ktere se museji
prenaset specialnim zpusobem.

> wek

*------------------------------------------------------------------------*
|                          Petr Simek   APS JU                           |
|                             psimek@jcu.cz                              |
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