16F84A "Development Board"

Discussion in 'Embedded Systems and Microcontrollers' started by tracecom, May 19, 2012.

  1. tracecom

    Thread Starter AAC Fanatic!

    Apr 16, 2010
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    When I found that my Low Pin Count Demo board didn't support 18 pin PICs, I decided to see what I could come up with. At the risk of getting a "Rube Goldberg" award, I have attached a photo.

    My "development board" is built on a perfboard and is set up especially for the 16F84A. (Yes, I know it's outdated, but there's a lot of code available for it, and I have a PBP tutorial book that uses the 16F84.) I built the board to connect directly to the PICkit 2. I also brought all 13 I/O pins out through jumpers so that they can be individually disabled. The 13 I/O's exit the board through header pins from the bottom of the perfboard, and plug directly into a solderless breadboard.
     
  2. nerdegutta

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    Dec 15, 2009
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    I'm using the PIC 16F628 chip.

    Guess I'll get the reward for my two boards:
    [​IMG]

    [​IMG]

    Both boards are built with ICSP for the Asix Piccolo programmer. I don't use that anymore. Now I use either the Asix Presto or Microchips PICKIT3. Matter of fact, I'm use the PICKIT3 more and more.
     
  3. absf

    Senior Member

    Dec 29, 2010
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    Use battery for supply. ICSP programmable, small size so very portable. So with a laptop, you can use it almost anywhere....I think you should get a bigger breadboard in case you need 7-segment display or LCD.

    But I have 2 development boards that support 18p PIC and one that supports 40p PIC, so no I am not going to build one like yours.

    Allen
     
  4. tracecom

    Thread Starter AAC Fanatic!

    Apr 16, 2010
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    After seeing nerdegutta's boards, I am going to add 13 LED's to mine; I think they will fit just below the shorting clips. :)
     
  5. MrChips

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    Oct 2, 2009
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    Here is my PIC proto-board:

    [​IMG]
     
  6. nerdegutta

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    Dec 15, 2009
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    Nice, clean and simple!

    I see you have the Rube Goldberg connection on the PICKIT2. :D
     
  7. MrChips

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    Oct 2, 2009
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    It is simply a straight long 6-pin header that I bent to 90-degrees.

    BTW, the reason I am using a commercial mounted protoboard rather than a protoboard alone is because students have damaged about a dozen boards by overheating. Hence I have a lot of these laying around.
     
  8. atferrari

    AAC Fanatic!

    Jan 6, 2004
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    How they managed to do that and what was the actual damage?

    If you use them, they are no bad , I guess. (??)
     
    Last edited: May 21, 2012
  9. Wendy

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    Mar 24, 2008
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    Last edited: May 21, 2012
  10. MrChips

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    Oct 2, 2009
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    [​IMG]

    Here is an example of a mild case of warped plastic. All the damaged boards are distorted in a similar fashion, much worse than this.

    I did not actually witness how the boards got damaged. I can only speculate. Any thoughts?

    It simply means that you cannot insert a 0.3" DIP IC at this location. Otherwise the rest of the board is perfectly usable.
     
  11. BMorse

    Senior Member

    Sep 26, 2009
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    I have seen that plenty of times, especially when power to an IC is connected backwards and overheat the IC,
     
  12. ErnieM

    AAC Fanatic!

    Apr 24, 2011
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    When you let the magic smoke out of ICs sometimes it comes out so fast it can bend back the plastic. Or maybe overheating an IC deforms the thermoset plastic (but I prefer the former rational).

    It is getting close to 40 years since I've actually used these boards thought I believe I melted them a few times like this. As long as the metal strips behind the plastic are intact you can work those holes larger to get leads to fit back into the board and keep on using them. Small drill bits or a sharp Exacto work well.

    The worst that can happen is the metal tabs spread and they no longer make contact. If that happens you may be able to peel back the bottom (mine was thick paper), extract the metal tab, and press then ends back together. The reassemble.
     
  13. Wendy

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    Mar 24, 2008
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    Protoboards were new, and my instructor had a brainstorm to use a 115VAC connection for a op amp power supply (741 chips, ±15VDC power supplies). A fellow student quickly showed him the fatal (figurative) flaw in his logic when he absent mindedly plugged the board into the real 115VAC plug. It wasn't minor melting, but a smoking hole. After that we were required to buy our own protoboards.
     
  14. THE_RB

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    Feb 11, 2008
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    Weird! It can't really be a cooked IC because they would go in the inner holes, which obviously had nothing in those holes as the plastic is almost closed up. A cooked power resistor would leave a different melt pattern, concentrated right under the body.

    In the case of your photo it looks like the heat was right in the centre of the thing, possibly in combination with some mechanical force pushing outward?

    Maybe they held a soldering iron near the middle of the board? That might cause that melt pattern. Of course if there was no soldering iron at hand then it's more of a mystery. :)
     
  15. coldpenguin

    Active Member

    Apr 18, 2010
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    Something like a pic18F could be that wide.
    I am surprised it would leave damage like that though (not that I have ever reversed the voltage on one ;)
     
  16. BMorse

    Senior Member

    Sep 26, 2009
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    I have seen this plenty of times, the IC heats up over the center opening which causes the plastic closest to it to melt first, which causes it to "collapse" outwards..... actually just did it a couple of days ago myself, didn't check my power leads and swapped the + and - (always better to use breadboards with color coded strips for power :) ), this is what the breadboard looks like after pulling the 74LS04 IC out of the breadboard....
    burnt breadboard.jpg :D
     
  17. MrChips

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    Oct 2, 2009
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    Thanks for the firsthand evidence as to how to warp the breadboard.

    Mods - sorry about hijacking this thread. You can split it off if you wish (from post #7).
     
    Last edited: May 23, 2012
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  18. THE_RB

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    Wow! Thanks for the correction! :)

    I feel a bit like a noob, I've used breadboards for 30 years and never cooked an IC like that yet! :eek:

    Mind you I've had a few holes get melty from hot resistor legs... ;)
     
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