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.
Ok, I did more poking around, and now have more info
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