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
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