Issues with JDM and other homebrew PIC programmers.

Discussion in 'Embedded Systems and Microcontrollers' started by mikejp56, Aug 10, 2015.

  1. mikejp56

    Thread Starter Member

    Jun 14, 2015
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    Hi All,
    Just a few thoughts about JDM and other homebrew PIC programmers.
    I have read on this forum where people should stay away from building their own programmers and buying a commercial product. The reasons given range from technical incompetence to figuring out how to use someone's DIY programming software.
    I have been an electrical engineer for over 30 years specializing in analog and digital design and prototyping. Hence I know my way around scopes and soldering irons. I just recently got involved playing around with PICs, and I needed to build a programmer. I decided on starting with a JDM programmer, and then working up to a USB PIC programmer. This made perfect sense because the project USB PICProg uses an 18F2550. However it needs to be programmed. So I started out with a serial port JDM programmer; 2 transistors and a handful of support components. It works like a champ. Also it was built correctly the first time. If someone is not paying attention, it is easy to miswire the transistors, swap ICSP leads, etc.
    Now granted this was a no brainer for me, but to call this simple class of programmers crap is, IMHO, not being fair.
    I had more problems with the software side than the hardware side; programmer type, config bits, registers, etc.
    My homebrew JDM has worked flawlessly for me while tinkering with the 12F683, and I am just waiting to get the parts needed to put together USB PICProg.
    Thanks for reading, and have a nice day!
    Regards,
    mikejp56
     
  2. MaxHeadRoom

    Expert

    Jul 18, 2013
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    I just wonder there is sufficient advantage when the Pickit2/3 can be picked up cheap?
    Max.
     
  3. mikejp56

    Thread Starter Member

    Jun 14, 2015
    49
    1
    Hi Max,
    I find it is more fun to pick up a schematic, round up the parts, and have a working unit when done than to unpack a box, plug it in, and go. I guess that is what it's like when your job is also your hobby.
    Regards,
    mikejp56
     
  4. jpanhalt

    AAC Fanatic!

    Jan 18, 2008
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    I really have never used a JDM programmer; however, I have experience with PicStart Plus,PK3, and ICD3. From my perspective, the advantage ICSP hardware simulation, Microchip forums devoted to their devices, and Microchip support more than make up for the $25 cost difference, if that, between a JDM and PK3 programmer. If your Microchip programmer fails to work, all you generally need to do is make a phone call, get the replacement, and ship back the defective unit in the same box.

    John
     
  5. MaxHeadRoom

    Expert

    Jul 18, 2013
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    I am not familiar with the JDM prg but I gather it is just a hex programmer? If so does it have the ability to use the Picmicro Signal gen and logic analyzer/USART monitor as well as a in circuit debugger as does the pickit2?
    Max.
     
  6. ErnieM

    AAC Fanatic!

    Apr 24, 2011
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    So just how good is this JDM programmer at in circuit debugging?

    Personally, I have more problems with the software side than the hardware side; programmer type, config bits, registers, etc so having a debugger on hand is, well, handy.
     
    DerStrom8 likes this.
  7. mikejp56

    Thread Starter Member

    Jun 14, 2015
    49
    1
    Hi Max and ErnieM,
    The JDM programmer has no bells and whistles (bells or whistles?). It is a strictly load the hex file and stick it in the chip device. I can see myself having SW issues, so there might be a pickit2 in my future.
    Regards,
    mikejp56
     
  8. MaxHeadRoom

    Expert

    Jul 18, 2013
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  9. Art

    Distinguished Member

    Sep 10, 2007
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    My experience with JDM programmer was not good.
    Trying to use DOS software on an old x86 laptop.
    It would be a trap for some, the low level serial ports out there that didn't meet programming voltage of older pics.

    My Picall kit programmer did work well with ICprog free software for years,
    But now I wouldn't give up my PickitII.
     
  10. bighand

    Member

    Apr 2, 2009
    18
    8
    The problem with the JDM design is the same as with the more complicated programmers like the Willem - it relies too closely on the serial port voltage. You can build a JDM/Willem programmer and it might work fine, but then you plug it into another computer and it doesn't work correctly, or at all.

    20 years ago every PC had a serial port, and every serial port had +/- 15V as per the RS232 spec. But these days even the PCs that still have serial ports rarely put out the full 15V. You might get 5V if you're lucky - high enough that a typical serial device will still accept it, but not enough for devices like EPROM programmers which really need higher voltages to work correctly.
     
    absf likes this.
  11. panic mode

    Senior Member

    Oct 10, 2011
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    the only real issue with JDM programmer is that it takes power from RS232 port. spec for RS232 says that logic1 is any voltage -3..-25V and logic0 is +3..+25V. in the past RS232 ports provided higher voltage levels and allowed higher current than what is today common. today RS232 port is considered legacy and most are part of some low power USB/232 converter. this means that same JDM device will happily work on some computers, not work at all on others. that is why some ended up adapting JDM to use batteries or other source of power.
     
    absf likes this.
  12. Art

    Distinguished Member

    Sep 10, 2007
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    Boycott manufacturers until the RS232 serial port is back I say!
    Need a terminal for some simple debugging and it's now an ordeal.
    I still use a vintage Commodore Amiga for it's proper serial port and terminal programs!
     
  13. be80be

    Senior Member

    Jul 5, 2008
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    You can build a pickit2 its easy as pie. the only real problem is programming the 18f2550 the first time.
    This is what I used it works great and is cheap to make.
    [​IMG]
     
    absf likes this.
  14. DerStrom8

    Well-Known Member

    Feb 20, 2011
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    I tend to recommend the commercial products (PICkit2/3) because of their ICSP and ICD capabilities. I use it as a debugger more than I use it as a programmer, so a JDM programmer is of little use to me.
     
  15. ErnieM

    AAC Fanatic!

    Apr 24, 2011
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    I would strongly suggest for someone buying their very first programmer/debugger to go with the PICkit 3 as it has full suppport for all devices going forward.

    A PICkit 2 is a very good device but is lacking support for the newest devices, something that will not change.
     
    DerStrom8 likes this.
  16. DerStrom8

    Well-Known Member

    Feb 20, 2011
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    I agree. I bought my PICkit2 back when the PICkit3 was first coming out and had a lot of bugs. If I start doing more PIC programming, I'll definitely buy a new PK3.
     
  17. MaxHeadRoom

    Expert

    Jul 18, 2013
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    I have both, but where possible I use the Pickit2, it is the extra features of course, but also not so quirky as the 3.
    Max.
     
  18. be80be

    Senior Member

    Jul 5, 2008
    431
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    Mike if you like building your own plz have a look at my post the sch is for a pickit2 it works wonderfully. I have a real pickit2 and I can say the one I made or the 10 I made and gave away to people worked great. I use one just like it I came up with the sch after using a junebug which is a pickit2 clone. But if you like building i would build that next. And as far as debugging goes it does that too just not as many chips as a pickit3. But if you like messing with code you can add your own new chips to the device file there a editor for that I've only used that onces to add a pic32 chip. Add you can always debug the old way with just a led on a port pin add a line to turn it on move that line of code to fine where it stops running. Don't like that I posted code some where that uses 15 lines to send date out serially called a backdoor which can really give you a most anything you want to send. Trick is to call it before your code stops doing what you want.
     
  19. ErnieM

    AAC Fanatic!

    Apr 24, 2011
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    Of course, if you roll your own programmer like be80be did you open whole cases of cans of worms you may never expect, like you have 3.3V max device and try to hit it with 5V, no in circuit debugging, and of course, how do you program the PIC inside the programmer before you have a programmer.

    Yes, you can build your own programmer, I've done it too for a special project where one PIC is running the test stand and programs another PIC under test before testing it. But I have multiple units of the PICkits 2 and 3 plus the ICD3 to load and test everything out.

    Especially for someone just starting out use all the "known good" items you can, and if that means buying a known good programmer, buying a known good development board, and (hopefully downloading and not buying) known good PIC code.

    Run some example code, then modify it. It keeps your sanity.
     
  20. be80be

    Senior Member

    Jul 5, 2008
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    ErineM your right about how to load a pic chip for a pickit2 clone the 18f2550 doesn't like jdm programmers the op will find that out when he gets his 18f2550 in.
    I've built a bunch of programmers and the would work fine on most 16f chinps but they didn't work with the 18f2550. The op may find that out. And it may work never know that's a jdm for you.
     
    Last edited: Aug 14, 2015
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