Re: [avr-chat] Funny verification happenings with uisp and avrdude on a ATMega8L

[Stuart Longland]

On 21/08/12 17:37, Erik Christiansen wrote:
> On 19.08.12 18:11, Stuart Longland (VK4MSL) wrote:
> The problem may be that the "programmer" is minimal hardware, directly
> driven by the software, given that a USB-serial dongle does not work in
> real-time. The packetisation makes the link run like an urban bus
> system - nothing for an hour, then 3 at once. Your simple programmer
> probably requires some software timing, which requires a direct serial
> link.

Indeed, it's a timing issue.  I thought by slowing it down it might get
around the USB latency issues.  For serial console work, it's fine, but
any clever legwork with the handshaking lines and it trips up.

This is, as you point out, probably more to do with the protocol used
over the USB link than anything else.  Likely, it waits until fills up
some buffer to a minimal level before sending.  Hence why it comes in
bursts that cause problems.

> I've used a Prolific PL-2303 based USB serial converter successfully
> between linux and a BDI2000, for loading embedded linux to flash. I've
> just now used it to talk to an STK500, via avrdude. I don't have an AVR
> board to hand this instant, so can't try programming today, but the
> STK500 will not rely on any host timing, AIUI.

No, I do believe those actually implement a proper RS-232 serial link.
They're not relying on bit-banging a synchronous link.

Of course, tell this to sales people when you ask about a laptop with
RS-232. :-)
-- 
Stuart Longland (aka Redhatter, VK4MSL)      .'''.
Gentoo Linux/MIPS Cobalt and Docs Developer  '.'` :
. . . . . . . . . . . . . . . . . . . . . .   .'.'
http://dev.gentoo.org/~redhatter             :.'

I haven't lost my mind...
  ...it's backed up on a tape somewhere.