Re: [avrdude-dev] PDI capable bitbang programmers?

[Ing. Daniel Rozsnyó]

On 05/05/2013 01:14 PM, Szymon Ulatowski wrote:
> On 05/05/2013 10:52 AM, "Ing. Daniel Rozsnyó" wrote:
> > I have started to compare TPI and PDI - seems very similar. The TPI
> > has a dedicated reset wire, so PDI looks like a subset of TPI, with no
> > modification required.
>
> last year i considered implementing PDI on FTDI but i gave up after
> learning that FT232R is unable to produce long and stable sequences of
> clock signal because of its hardware bug - the chip spits out all
> received data very quickly instead of buffering the packets and clocking
> output pins according to the configured frequency - see "TN_120 FT232R
> Errata Technical Note" - "3.1.2 BitBang Mode variable Pulse Width"
> http://www.ftdichip.com/Support/Documents/TechnicalNotes/TN_120_FT232R%20Errata%20Technical%20Note.pdf
>
> and this is very unfortunate because PDI requires at least 10kHz clock -
> ideally we would configure the output clock to 20kHz (or more) and send
> an USB packets of 01010101 - but they screwed it and the result is a
> quick burst of clock followed by a pause (and pausing the clock
> disconnects PDI) :-P
> so i gave up and decided to implement PDI in USBASP that is so
> ubiquitous and cheap
> http://szulat.blogspot.com/2012/08/atxmega-programmer-for-050.html
>
> but of course the FTDI implementation would be so much better (if it is
> really possible) and i wish luck to anyone trying to accomplish this goal!
>
> sz.


I have tried - no luck.

The no use of PDI before was caused by not patching the usbasp firmware 
with your patch - sorry. After application, the PDI mode was selected 
for my x32a4u part. Might be good to warn the user on lack of support.


But I won't get pass this:


avrdude: initialization failed, rc=-1
         Double check connections and try again, or use -F to override
         this check.


avrdude done.  Thank you.



The signals look now very correct - but I had to remove the 100n reset 
capacitor, as it did not get discharged at the 60-80 khz PDI_CLOCK (had 
to use 1K series resistor instead of 820R+220R, but should not matter).

Will buy or borrow a JTAG ICE3 probably. I have no way to know where is 
the issue is.

Daniel