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Question about no Propeller Chip found — Parallax Forums

Question about no Propeller Chip found

RDL2004RDL2004 Posts: 2,554
edited 2012-10-13 07:18 in Propeller 1
Will the Propeller fail to be detected if the eeprom is bad/missing?

I just wired up a board to use the Propeller chip that I got in the "Mystery Bag". I had checked all the voltages and checked for shorts and everything looked good. I then plugged in the Prop and the eeprom but somehow when doing that one of the LM317 resistors broke and both chips saw 6+ volts. I fixed the problem and replaced the Propeller but I don't have another eeprom. The Propeller Tool still doesn't detect a Prop. I just need to know if the eeprom could be the problem or if I need to dig deeper. Also, I checked my Prop Plug with another board and it's working fine. Thanks for any help.

Comments

  • ratronicratronic Posts: 1,451
    edited 2012-10-11 17:53
    Rick the Propeller does not need a EEPROM or a crystal to be detected.
  • RDL2004RDL2004 Posts: 2,554
    edited 2012-10-11 18:36
    I didn't think it did, but I can't find anything wrong. I have 3.22 volts from the LM317, no shorts between any of the i/o pins or power and ground. Rx to pin 40, Tx to 39 and RST to 11. I guess I'll give up on it for now, maybe pull the Prop and try it in a breadboard tomorrow. It's too bad cause the board was looking pretty good, right up to the point where it didn't work :)
  • ratronicratronic Posts: 1,451
    edited 2012-10-11 18:45
    If you know the com port# of your Prop plug, in the Prop tool under Edit/Preferences/Operation in the Communication box it will have a drop down menu of available com ports to select from. See if your Prop plugs com port# is shown in the list.
  • RDL2004RDL2004 Posts: 2,554
    edited 2012-10-11 20:14
    The Propeller Tool finds my Parallax protoboard just fine on the same Com port with the same Prop Plug. I guess that's not the problem.

    I pulled the second chip out of my board and wired it up on a breadboard and it's no go. DOA apparently, or maybe my board killed it, though I still can't find anything wrong with it. Maybe next Mouser order I'll buy a few more chips, but test them on a breadboard first.
  • jazzedjazzed Posts: 11,803
    edited 2012-10-11 21:20
    Using a PropPlug? PropPlug Tx should point to pin 40 (p31).

    Got a picture?
  • RDL2004RDL2004 Posts: 2,554
    edited 2012-10-11 21:41
    What? The manual says Rx > 40 and Tx > 39

    Edit: oops, now I see what you mean.
    PropSchematic.png
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    PropBoardTop.jpg
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  • RDL2004RDL2004 Posts: 2,554
    edited 2012-10-11 22:48
    Yep, that was the problem. Not only that, but the first chip actually still works (well, its found anyway), even after getting zapped with 6.5 volts. Don't know about the eeprom yet. The fix was not pretty. That board was cheap and apparently the pads are good for only one soldering. Oh well, live and learn. Thanks so much for finding my mistake. I'm sure the next board will turn out much better :)
  • SapiehaSapieha Posts: 2,964
    edited 2012-10-12 01:01
    Hi RDL2004.

    What about to add some decoupling's capacitors around Propeller --- If You will not burn PLL in it?


    RDL2004 wrote: »
    What? The manual says Rx > 40 and Tx > 39

    Edit: oops, now I see what you mean.
  • RDL2004RDL2004 Posts: 2,554
    edited 2012-10-12 06:45
    What about to add some decoupling's capacitors around Propeller --- If You will not burn PLL in it?

    Yes, this is a very good idea. Fortunately I had already done it, it was simply not visible because they were hiding under the chip :)

    In this photo you can see the decoupling capacitors. You can also see the board as it was fixed. The socket at pins 39 and 40 was damaged beyond repair, so I had to transplant a section. Luckily, at this point only the corner and center section pins of the socket had been soldered down. This was just a sort of prototype board and there were a number of mistakes made while building it and there are several things that could be improved, I'll probably make an new version next week. I expect it will turn out much better.
    PropBoardRepair.png
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  • StefanL38StefanL38 Posts: 2,292
    edited 2012-10-13 07:18
    Hi Rick,

    as the DIP40-socket got damaged - maybe I'm quoting something you know very well - just in case not
    desoldering is much easier with a desoldering vacuum pump.
    http://www.amazon.com/Desoldering-Vacuum-Solder-Sucker-Removal/dp/B003FHYL7I

    For desoldering as long as the copper-dot is hot the glue that sticks the copper to the PCB is melted.
    As long as the glue is melted you shouldn't apply any mechanical forces to the copper-dot. Not by your soldering iron
    not by a wire.

    The desoldering vaccum pump sucks off the melted solder. With this you desolder pin for pin.
    After that all the pins is free and you can pull the socket out of the pcb
    just as like on a virgin PCB with nothing soldered yet.

    Take a look into this thread where I posted two pictures of a DIY-board I made to see additional things
    that I put on the board to get overcurrentprotection.

    http://forums.parallax.com/showthread.php?143052-Low-Cost-DIY-Propeller-Board-with-overcurrentprotection

    best regards

    Stefan
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