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drzaiusx11

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Posts posted by drzaiusx11

  1. Posted

    My guess is they're going with an ohm meter like design (http://www.circuitbasics.com/arduino-ohm-meter/) where they're using the 1M resistor as the "known" resistor and the pot from the paddle is what you're solving for. They probably put the other paddle output into a high impedance state so it won't mess up the reading since the two paddles share pin 7, then swap. Going with the resistor + cap charger circuit would work too (and be just like the real atari), but would require 2 more caps and also messing with interrupts.

  4. Posted

    Who's Blinky and what's his design? I assume without any external chips you can just wire the io pins directly to a card edge connector.

     

    As for line delay, I arbitrarily chose the recommended time delay from an old EEPROM datasheet I found from the early 80s--I may be able to get away with a similarly short time, but most ROMs dump in under a second with my current value so I didn't feel like risking anything shorter for now. The arduino and wiringPI APIs may add some overhead when setting the IO pins that may make adding delays superfluous, but without a decent scope I can't easily check.

  5. Posted

    Yeah, the official ardiuno products are pretty pricey, but I don't mind supporting the team behind them so I usually end up just paying the "arduino tax" for my stuff. Pretty cool you can get a mega for that cheap nowadays--googling around shows you can get a knockoff of pretty much any arduino product for under $10 USD which is pretty sweet. Its amazing what you can get for your money on bangood and aliexpress these days. I guess its a great time to be a hardware enthusiast.

     

    Price wise I'm investigating the new $5 pi for my project. I've tested it on the A+ and B+ so far, but there's no reason it shouldn't work on the new board too since it has the same pinouts and ARM chip. The damn things are pretty much sold out everywhere though, so it may take a while to get my hands on some. The A+ isn't a bad deal at $19 though.

     

    At some point I may put up my arduino shield schematics in case someone with an UNO wants to give it a go--do you plan to publish your sketch as open source? With a bit of fiddling I bet I could get your code working on my UNO (I don't own a Mega atm)

  6. Posted

    If you want to take your costs down even more an arduino UNO retails for $25 while the mega is $45 (USD.) I assume you're making a PCB shield as well, so the added costs of 2 shift registers would be under a $1 (they go for around $0.30 to $0.50 each), so that could shave off about $20 off your current design.

     

    I can share my sketch that handles treating the shift registers as extra IO pins too

  7. Posted

    Cool! My dumper started out as an arduino uno with a couple of shift registers to get the io ports needed. That's why I'm using the wiringpi library, so I didn't have to rewrite my code when I switched to the PI ;-)

     

    I could refactor out the pi specific parts of my dumper and make a tiny shared lib with detect and dump routines if there's any interest in combining efforts.

     

    I'm down for at least taking a look at what you've done so far.

  9. Posted · Edited by drzaiusx11

    UPDATE: boards are in and work great! I found a few more bugs in my dumper software though, so I'll be updating that soon. So far all my carts work with the exceptions of River Raid II and Pitfall II, but I'm fairly certain those issues are software related and not the actual hardware.
    Here's an assembled unit:
    post-6572-0-25701200-1447121067_thumb.png
    post-6572-0-45645900-1447121166_thumb.png

     

    I'm currently toying with the idea of adding colecovision and possibly intellivision ports to the board as well. Looking at the cart pinouts, colecovision should be dead simple since there isn't any bankswitching--the intv's pinouts seem a bit more complicated though (and I have less intv carts to test.)
    I still need to design an enclosure as well...

    post-6572-0-45645900-1447121166_thumb.png

    • Like 2

  10. Posted

    So I finally got around to exporting the schematics / layout files. I've also moved the joystick ports / switches to an expansion board that will attach via the JP3 port (controlled by a $0.99 PIC microcontroller) However, the controller port board is still WIP.

     

    I finally ordered a new set of boards today, so in the coming weeks I should have something to send out for testing.

     

    PS Awesome mini arcade cabinet!

     

    post-6572-0-70040900-1444358102_thumb.png

    post-6572-0-55172300-1444358168_thumb.png

    post-6572-0-17306900-1444358183_thumb.png

    • Like 1

  13. Posted · Edited by drzaiusx11

    Hey Startdust4Ever, no problem! Once I get the boards in after my latest revisions I can send you one at cost to play around with if you want.

     

    You can wait till it's "done"--However, I'm fairly certain the hardware for dumping is pretty solid at this point.

     

    Here's the items next on my todo list

    - vcs compatible joystick ports

    - difficulty switches

    - tv type switches

    - reset button

    - acrylic laser cut case

     

    If you only want the final product and just use it for dumping, I'll make sure the board can be populated with just the hardware needed for dumping and nothing else (to keep costs down)

  15. Posted

    Just put the ROM mapper auto detection and dumping code up on github:

    https://github.com/drzaiusx11/pitari

     

    The board plans and Raspberry Pi SD card image will come next, but for now if someone is interested its fairly easy to figure out the wiring by looking at my address and data assignments in the code. Just don't hook the data lines from the carts directly to the RPI since it needs to go through a buffer to convert from 5v -> 3v (otherwise you'll fry your pi.)

  18. Posted

    If my boards on order work out I can put some up on tindie.

     

    I do plan on adding bw/difficulty/reset switches and joystick ports to the design though, which may not be wanted in a dumper. My final goal was something like a better fb3 (ie full console.)

     

    But as-is the design works fine for a simple cart dumper. It'd even be trivial to write a script to dump straight to a USB drive or some other media.

  20. Posted · Edited by drzaiusx11

    Thanks Eckhard! So my first source is more correct since it still depends on the data bus for choosing the bank (Not just hot spot address reads.)

     

    Do you think I can safely set the D5 pin from my GPIO without damaging the cart (or my GPIO port)? Naturally it would be in contention with the output of the ROM chip.

     

    Presumably I should also avoid reading $01fd, $01fe and $01ff in that order when dumping the cart as well?

     

    As for pictures:

    http://imgur.com/a/B1MMM

     

    Its not much to look at right now, but I have some boards on order through batchpc that should be in soon so I can ditch this rats nest of wires.

     

    I'll take a video of decathlon playing once I get this issue sorted!

    • Like 1

  22. Posted

    Hey Folks,

     

    Some background: For the past few weeks I've been working on a small hobby project to implement my own 2600 clone using a raspberry pi computer that plays actual 2600 carts through an adapter board tied to its GPIO pins (I've been tentatively calling it the "pitari.") The pi boots into my application which dumps the rom and then loads stella. I basically wanted a retron5 for my 2600 carts since my heavy sixer finally died and my 7800 is on the fritz after a svideo mod gone wrong (plus my tv sucks at upscaling.) Anyways...

     

    I've been having a lot of fun learning how carts, roms and mappers work. I have 2K, 4K, E0, E7, F6, and F8 carts loading fine now but I'm having some trouble with FE carts. I'm using this doc as my reference for implementing my mapper detection and dumping routines. The few (2 dozen-ish?) carts I own seem to work now with the exception of Decathlon (which is an FE cart.)

     

    TL;DR: I can't for the life of me come up with a simple method for dumping FE carts since the code on the ROM itself is apparently used to switch the banks. Anyone have any clever ideas on how to dump these carts? It has obviously been done before, so I'm clearly missing something. Maybe just test a range of addresses after each read to see if I've swapped banks? Ideally, I'd like to come up with something that would work in the general case and not just the few commercial carts out there as FE (Decathlon & Robot Tank?)

     

    Any help would be appreciated. If there is any interest I can release my code and/or schematics as well. At the moment the adapter board is literally just a 24pin card-connector and a 74LVC245 chip to do 5V -> 3.3V conversions on the data line to make it compatible with the pi's 3.3v inputs.

     

    Thanks,

    Jeff

     

     

     

    • Like 1
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