osmocon and boot loader experience

Sylvain Munaut 246tnt at gmail.com
Tue Jan 18 15:17:31 UTC 2011


> My conclusion is clear that it is not a matter of physics (electrical) but of timing constraints.

If you can see the PROMPT1 / 2 and the download either doesn't finish
or you get a NACK, then yes, it's probably timing.
If you don't see PROMPT1/2 then it's electrical.

The bootloader serial routing is stupid as hell ... basically you have
: (from memory but the idea is there)

uint8_t read_char()
  for (int i=0; i<4096; i++)
    if (is_char_ready())
      return get_char_from_buffer();
  return 0;

So basically if it doesn't get a char in time, it return 0x00 and the
caller has no idea if the 0 is a received char or a timeout ...

> - after loading the firmware none of the cables ever made any problems
>  (thanks to Harald's HDLC layer:-)

It's both the HDLC and also the fact the uart is handled _way_ better
in our code than the

> - Prolific is noisy, that means if the plug is not connected to the phone you will see
>  endless random characters received my osmocom

Probably depends on the cable ... some prolific could have a pullup/down.



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