Re: Manchester Decoder


Luhan wrote:
John Larkin wrote:
On Mon, 30 Oct 2006 09:57:29 -0700, Jim Thompson
<To-Email-Use-The-Envelope-Icon@xxxxxxxxxxxxxxx> wrote:

Anyone have a simple-minded design for a Manchester Decoder?

Thanks in advance!

...Jim Thompson

If you detect transitions of either direction, and fire a
non-retriggerable one-shot of 0.75T duration, you'll recover an
unambiguous clock. The rest is easy.

John

'Pure' Manchester code can have pathalogical groups of zeros or ones
making decoding impossible. You also need to either use either Async
(start and stop bits), or Sync (leading known sync byte) to be able to
decode reliably.

Luhan

Now that I recall, my earliest one loaded an assembler program into a
wirewrapped 8080 machine using a version of Manchester. The only
hardware was a single comparator connected to the headphone jack of a
portable cassette player. This fed a variable width bit directly into
an input port. The decoding (as well as the encoding) was all done in
software.

Luhan

.

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