USB Serial cable programming grief !

J

Janne

Senior Member
Inspired by this thread, I went back to my "defective" axe027 cable. Before, the cable didn't work with any boards i tried(all of which worked with the normal serial cable). It just showed 2.1V with the test led "on", which i suppose was too low for the picaxe to recognize.

I had even ripped open the covers on the cable before, to look for any obvious problems inside, but nothing looked like it was broke so i threw it in the locker.

Now, to my surprise, as i plugged it into my laptop, and onto my AXE090 experimenter board.. voila, it did recognize the picaxe on the board. But then i tried it on another picaxe board that i had previously assembled on vero board, and again the same thing.. connection error, and even the program running on the axe seemed to crash. And after that, the experimenter board doesn't work either anymore, again it's just showing about 2.1V with the test led on. (both boards still work with the normal serial cable, and with the usb port adapter)

I now suspect the problem might lie in the soldering of the IC chip(a cold solder in somewhere, mayby).. too bad it seems to be a qnf package, so it's impossible for me to try and fix it.
 
J

Janne

Senior Member
SilentScreamer said:
I assume you meant QFN?
Click to expand...
That's right, sorry for messing up the terms.

I also found out the problem with the usb cable. I started taking a closer look into the pcb and circuit, but ran into problems early on trying to decipher what wire was what in the cable. TxD and RxD were quickly found, but ground seemed to have no connection. I then spliced open the 3.5mm stereo jack, only to find out that the black ground wire was cut!.. mayby during the process of moulding the plastic onto the plug? Anyways, i re-soldered the ground wire back onto the plug, and hey presto, now it works with every board i have, every time.

How did this cable then work a couple of times when i tested it? I only can guess, that it did get some "trace" ground, just enough to work for a few times though not reliably. Also, i wonder why does the cable have 6 wires, when only 3 of them are used..

edit. It also now makes perfect sense, why i have seen 2.1-2.3V in the serial input pin with the test "led" without the ground connection. Because the serout pin of the picaxe is normally low(connected to the ground), the download circuit together with the 10k pulldown resistor inside the axe027 RxD line make a voltage divider circuit. Might suggest that this is also the case with the op, as there seems to be similar voltages present.
 
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T

Tim036

Member
Final post on this thread.....

The replacement cable AXE027 USB arrived and on the LED test set to COM5 it swung from 0 to +5v like a 'good-Un' and downloaded a prongrame no probs.

What is to be learnt now its all over, the company replace faulty goods by return ! Brilliant !

If anyone else reports this problem using the 'Test' led and gets these faults, chances are the earth wire (or something) has fallen off inside the AXE 027 cable.

Fix:- get it back to the company and they will sort out out asap , faster than this thread managed. Reason... probably very rare event.

Again many thanks for all those Forum members who posted on this thread. Very greatly appreciated.

: )))

Tim
 
J

Janne

Senior Member
Nice to hear you got yourself a replacement so quickly.

The only thing why i bothered trying to fix my own, was that it would have propably costed more to ship the cable back to rev-ed for warranty, than just to get a new one... no doubt that they would have replaced my cable too.

I also ordered a bunch of picaxe stuff for work, including one axe027 cable. It had no problems, so i guess the few defect cables have been the few unlycky in a big run.
 
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Tim036

Member
Janne said:
Nice to hear you got yourself a replacement so quickly.

The only thing why i bothered trying to fix my own, was that it would have propably costed more to ship the cable back to rev-ed for warranty, than just to get a new one... no doubt that they would have replaced my cable too.

I also ordered a bunch of picaxe stuff for work, including one axe027 cable. It had no problems, so i guess the few defect cables have been the few unlycky in a big run.
Click to expand...
Postage by small packet it not that expensive within the EU unless someone takes a x5 on the cost !

Not testing 100% of the items on the finished goods saves money but guess who picks up the tab !

Hmmm...

:confused::confused:

Tim
 
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