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Thread: Oh FreHd, how thou hath thwarted me!

  1. #1

    Default Oh FreHd, how thou hath thwarted me!

    Hi Everyone,

    Well, I'm stumped, and I was hoping someone might be able to point me in the right direction. I bought three Kit B FreHD's about 1.5 years ago and built them all out. One worked right away, and another worked with a little SD card soldering fixes. The third however, never would behave. I tried swapping parts around on one of the good and bad ones, and accidentally installed the PIC backwards. After that, only one was working! I figured I had killed the GAL or PIC, so I wound up shelving them and then I sold the one working one with a Model 4P.

    When I bough the FreHD's I got the GAL & PIC preprogrammed, and I now have a Vstager VS4000 programmer which will program Lattice Gal's and 18F4620's. Well the 4620's are not too happy in this guy. Out of 11, I have two which seem to succeed. It really seems to have a problem writing the EEPROM. I wound up putting 3 10k resistors on the programmer to pull signal lines a little tighter, and it actually started to work. Before, it would fail to verify in the program code on nearly all of them, with the resistors, it fails on the eeprom on 9 of them, and 2 succeed. (Seems like the erase may be failing to wipe the EEPROM, it shows all 0x00's) Fred Vecoven was kind enough to send me the debug hex for 2.14, and I installed that on one of my good chips, and watched the serial port. On both boards, it shows the file system mounting just fine. To me, this means the PIC, SD, RTC, etc are all good on the boards. This leaves the GAL, the 245 & the 595.

    I have an IC tester, and all of my ICs are TI, new and test good. I tried LS, F, HC & HCT variants of all chips in multiple combos. I'm testing on both a FreHD eprom'd model III & 4(non gate array gen-2). I even went back to the original ROM, and tried the boot disks. They just hang. VHDUTL show no interface available.

    My programmer acts like it succeeds on the GAL with no issue, and it takes less than 2 seconds to program. The verify works just fine too, so it seems to be ok, but maybe not? Maybe the PICs are not working right? (I bought the PICs from Mouser, and the GALs from eBay, they seem to be discontinued now.)

    I'm at a loss now. I feel like I've tried everything that makes sense, and I feel like I've isolated down to the interface itself. As such, is there a better programmer for me to try for the GAL? I would think I made a mistake on the board somewhere, but I have two acting exactly the same, and honestly, one of these guys worked before at some point. I had to have killed the PIC or GAL to make it start failing, but I have all new ones now. All of the ICs are new on them now to be honest.

    I appreciate any guidance this group can provide! I'm really anxious to figure out where the issue lies.

    Take care,
    -Kevin

  2. #2
    Join Date
    Feb 2014
    Location
    Netherlands
    Posts
    364

    Default

    @Kevin.

    I tried swapping parts around on one of the good and bad ones, and accidentally installed the PIC backwards.

    This action causes a nearly full short circuit.
    There is a big chance there is a trace gone between J3 and J5. See the picture.

    short.jpg

  3. #3

    Default

    Unfortunately, they're still in-tact. That would have been a nice answer, but I just sat and ohmed out most of the power pins, and all look good. I also noticed Ian uses 15ns chips, and the ones I have are 25ns. I think this is the different between 40 & 66mhz, so I can't image this would matter. Just thought I would mention it.

    Thanks Hans.

  4. #4
    Join Date
    Feb 2014
    Location
    Netherlands
    Posts
    364

    Default

    @Kevin

    The trace I suspect is a ground line and is going beneath the J1 connector. You cannot see the trace.
    Have you removed all chips to avoid measurements through chips. For me the speed of the chips is no issue.

  5. #5

    Default

    Hi Hans,

    No dice, the ground and power wires are good across the board. Any other thoughts? (Also, I did have two acting up, but only one was ever plugged in backwards.)

    Any other thoughts?

    Thanks!
    -Kevin

  6. #6
    Join Date
    Feb 2014
    Location
    Netherlands
    Posts
    364

    Default

    @Kevin.

    The programmer doesn't sound very trustful.
    Swap the GAL & PIC from the working FreHD with one of the problem adapters.
    Ask somebody in your neighborhood to reprogram these devices, I can do it for you but it is very expensive and time consuming to
    send them to Europe and back to the USA.
    I think someone in the USA would be so kind to help you.

  7. #7
    Join Date
    Sep 2011
    Location
    Melbourne, Australia
    Posts
    798

    Default

    You can send it to me if you like. While the return rate (to help get their FreHD going) for the kit builders has been incredibly low (less than 5), I've always been able to sort them out in less than 1/2 an hour.

    Cheers,

    Ian.
    *There is never a charge for Tech Support even if you don't purchase from me - We are Enthusiasts Helping Other Enthusiast and that is just the way it is

  8. #8

    Default

    Thanks Ian. I appreciate the offer, but I'll try a few more things before I give up. I was just hoping it was something common, but it sounds like there many be more to this than I first thought.

    Anyone have a suggestion for a programmer? Something not too high, but better than all of the $50-$80 multi-burners out on ebay?

    Thanks!
    -Kevin (TexElec.com)

  9. #9
    Join Date
    Feb 2014
    Location
    Netherlands
    Posts
    364

    Default

    @Kevin

    Cheap and good mostly don't go together, but I have used this programmer for the FreHD with good results.
    Take a look at this programmer: http://www.ebay.com/itm/USB-MiniPro-....c100009.m1982

    But my best advise is: Let Ian help you, it is the cheapest solution and Ian is the most friendly and helpful guy I know.

    If you want to solve the problem by yourself, there is a known problem with the BS170, this is what the manual says about it:
    2A. It turns out there are two different polarities for the BS170 (Q1) and the Fairchild product I used for the first 100 or so FreHDs is backwards which is why it is mounted reversed to the screen printing on the PCB. If you are building a FreHD from scratch and it gives flashing RED LED and otherwise won't work, try changing the polarity and see if that helps.
    Last edited by Hans01; October 11th, 2017 at 11:10 PM. Reason: Added some info about the BS170

  10. #10
    Join Date
    Sep 2011
    Location
    Melbourne, Australia
    Posts
    798

    Default

    Although I have a lot of different programmers and tools, my preferred PIC programmer is the PICkit 2 w/ Sure Electronics ICSP and for Eproms/GALs I use a G540. Both are available for under $100ea. I also use a Ango LA6T Eprom eraser.
    *There is never a charge for Tech Support even if you don't purchase from me - We are Enthusiasts Helping Other Enthusiast and that is just the way it is

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