Sad Arduino

Hi! I've just got my first Arduino Duemilanove board, and am having strange troubles with it. When I connect it to USB and try to upload a sketch, it says

avrdude: stk500_recv(): programmer is not responding

But when I connect a scope probe to the RX pin of the 328, the upload goes ok! The same goes when I put my hand over the connectors (not touching anything metal).

If I use a 10x probe, the problem is back again, and the probe sees no signal on RX line.

So probably this is either a partly damaged FTDI chip, or some problem with soldering the board. Any ideas where I should look?

(Heh, I'm not too excited about resoldering the FTDI:)

There is a resistor connecting the FTDI chip to the serial input of the arduino. I would look for soldering problems round that area.
As it works with a scope probe but not a X10 one then it sounds like something is not being pulled up so look at the pull up resistors round the FTDI chip as well.

Happy hunting.

Thanks for the idea of checking various pull ups!

Ok, I did more poking around, and now have more info :slight_smile:

The serial send/receive is ok. The problem is with reset circuit. If I use a non-resetting stock avrdude and reset the board manually just before hitting enter, the upload goes ok. If I let the Arduino IDE do the reset, the upload fails regardless of manual reset -- so probably the reset pulse from the IDE brings the mega328 to some bad state.

Unfortunately I don't have a digital scope so I cannot view the reset waveform. I'll try soldering again the reset pullup resistor and probably other reset circuitry, but any ideas are more than welcome!

Ok, I gave up and cut the RESET-EN trace. Now I do manual reset and it all works ok.

I resoldered the 100nF cap and the pull-up resistor, but still did not succeed. I tried to measure the capacitance of C13 and resistance of R1, and they seem within the norm. Will have to do manual reset :frowning:

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