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johnnywc

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johnnywc last won the day on August 3

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About johnnywc

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  • Birthday 03/05/1968

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  1. This sounds very promising! Anything I can do to help? Should I look into buying some of these chips? Thanks! John
  2. Thanks for the update! It's weird that this only happens with non-modded Ataris using RF and there is absolutely zero interference with a modded Atari, even with the circuits that use 7404 and bus transceivers where the interference is much more prominent vs. the circuit with the NAND gates. Could that be a clue?
  3. You're welcome! I may be wrong, but I think you need to wire pin 5 to VCC (not GND) if you want the arcade stick to be recognized as a 2-button gamepad by Scramble since it's expecting INPT1 (paddle B) to be '1' on startup. Good luck!
  4. Hmmm, does it say "GAMEPAD FOUND" on startup? If not, then the auto-dectection scheme probably isn't working for the arcade stick based on a different reading of pin 5 on startup. Looking at the Scramble init code, it thinks you have a 2-button Sega Genesis controller connected if INPT1 (pin 5 on the Atari) is logical "high" on startup. Can you reach out to virtvic to see how he has wired up pin 5? If he grounded it (maybe he didn't need it), then unfortunately Scramble will think you have a 1-button joystick connected as this pin (and pin 9) are both 'low' when regular joysticks are connected. Hope this helps! John
  5. Thank you so much for the kind words! Galagon is set to be released at the Portland Retro Gaming Expo in about a month, and will be available in the Atari Age store sometime after that. Wow that's great news - thanks for sharing! I'm glad Galaga aka Galagon was a hit! Thanks Steve! We're busy working on getting a playable Zoo Keeper ready for PRGE - it's looking good so far!
  6. We have started on "Gorf Arcade", by request from our graphic artist @Nathan Strum, expected to be released sometime in 2020. And yes, it will have all 5 screens, plus voice using Atarivox.
  7. Okay, I do have a multimeter so I'll see if I can get a measurement. Let's hope it doesn't come to that. It's hard to tell since this is an RF connection and the picture isn't clear to begin with, but I was eagle-eyed on the area where it usually appears and didn't see anything. Okay, that makes sense. Thanks! John
  8. I hope I'm hooking the DC circuit up correctly. I have pin 7 going to a pin on the board, then the inductor between this pin and another on the board. I then connect the output of the inductor to my common vcc pin strip on the side. I connect pin 8 to the common ground strip on the board. I then add the capacitors with one pin on the common vcc and one pin on the common ground strip. I then pull off of vcc after the capacitors to feed the chips and resistor networks. Hope that makes sense; I can take a pic to clarify. Is it possible I fried the large capacitor when I connected it the wrong way (a couple times )? For sure the interference increases slightly but noticeably when I add the large capacitor and reduces when I remove it. Yes, I have 1M resistor networks on the 5 inputs from joystick 1, 5 inputs from joystick 2, and the combined output from the NAND gates prior to the 74HC05 which then goes directly into the Atari. I am using a 10K resistor pull up on the select line input and a 100K pull up on it's output from the 74HC05. Should I try a 1M on this too? Okay, I will give this a try. I changed my test program so it toggle the input select every 2 seconds (instead of twice a second). In this case there is no static, you just can only use 1 joystick every 2 seconds. I measured pin 9 with my multimeter and alternates between 4.98 volts and 0.16 volts every 2 seconds as expected. I think it was suggested above that there may be a situation where all the chips are active for a split second during the transition that may be drawing more power which is causing the interference? Maybe it's more noticeable when it's happening 120 times a second vs. once every 2 seconds. I'll keep you posted on my progress. Thanks! John
  9. The large capacitor causes more interference when connected. The small one doesn't seem to have any effect. I connected the large capacitor with the short pin (negative) to ground; the small capacitor doesn't seem to have polarity. The interference gets slightly worse when you press the joystick in one direction, but seems to almost go away when you press the joystick down and to the left or up and to the right. The interference seems to go away when you unplug both joysticks. Yes, I think that's how I have it hooked up. I originally had the resistor pull-ups connected to straight 5v as it wasn't clear in the original diagram, but I made the change and it didn't seem to have any effect either way. I can always ship you a unmodded 2600 if that helps and if you have the time to work on something like this. I want to also mention that the interference does go away completely if I disable switching or use the QuadTari with a standard Atari game (I use Basketball to test). The controls work great (it always uses joystick 1 since Basketball isn't setting DUMP_PORTS) but there is no interference. One last thing I want to mention; if I disconnect VCC (pin 7 from the Atari) completely, the circuit still works and there is no interference. I measured vcc at the chips and it's getting 4 volts somewhere, probably from the other Atari pins; I measured the select pin and the directional/button pins and they measure 4.6 volts). I'm sure it's not good for the overall circuit or health of the Atari/chips but thought it might be useful. I should stress that the interference is almost down to nothing compared to what it was before. Here is a pic and a short video so you get a visual. The interference are the white dashes: quadtari_inteference.mp4
  10. I had a couple hours free and wired up the design above with the 74HC03 and 74HC05 chips with the inductor and capacitors. Functionally it works great! The interference is much much less than the previous test with the x245 and 74HC04 inverters but still small traces at the top of the screen. Interestingly, the interference is worse with the capacitors; if I pull them out it's barely visible but with them a bright short line of interference shows at the top. The inductor doesn't seem to have much effect either as the interference seems the same whether or not the 5V vcc is connected to the chips directly or thru the inductor. As with the previous design, if I disable switching (DUMP_PORTS is always on or off), there is zero interference (but of course just 1 joystick works and controls both players ). I hope I'm connecting the capacitors up correctly! FYI The 74HC05 has 6 inputs/outputs so I was able to use 5 of them for the output prior to the Atari for the 4 directions/button and the other to invert the select line (the design above has the up direction hooked up to a NAND gate to save a chip but I was able to use the 05 instead since it really doesn't save a chip - you still have 3 74HC03's and 1 74HC05). For the select logic, I have the select pin 9 connected to a 10K pull up resistor before connecting it to the 74HC03's for joystick 1 inputs, and the output from the inverter (the inverted select line) I have hooked up to a 100K pull up resistor prior to connecting it to the 74HC03's for joystick 2. Does that sound correct? So it looks like we're getting really close! Any other suggestions? I can try a version with the LS641 open collector bus transceivers, plus I have the 240 octal buffers too.
  11. Update: The parts came in today so I hope to wire this up in the next few nights. Silly question before I blow up something; is there a specific direction I should be hooking up the capacitors? I read online that the inductor doesn't have polarity so that should be okay in any direction (I think) but read about capacitors blowing up if you don't hook them up in the right direction. 😮 Any safety tips are appreciated!
  12. Sounds like a good plan! I just got the open collector bus transceivers in the mail (74ALS641) so I'm going to swap those in in place of the x245 and diodes to see if that makes a difference, but from what you've found in your research it seems that the interference is most likely being caused by VCC on pin 7 which I won't be able to test until I get the inductor and capacitors in the mail. It's times like this I really miss having a Radio Shack around!
  13. Great thanks! I ordered the 7 items on the shopping list; they should be here by the weekend. Okay, I'm ordering 10 of each to save on costs (plus I'll probably fry a couple while I'm testing lol) so I should be able to mix and match to reduce chip count if needed. Okay, I have a 10K on the input side in my current design, so I can keep that. I'll add a 1M on the other end. Quick question; regarding the design above where we're using the 74HC04 to invert the select line; why isn't a 1M pull up resistor needed for that output? Does the 74HC04 pull up the value but the 74HC05 does not?
  14. Okay, so this looks very interesting and reminds me of my discrete logic class @ UCONN (CS207/208). It all makes sense to me except for the NAND gate connecting the Joystick pin 1's (UP); why is that being used instead of the inverter? EDIT: I think it's to reduce chip count? The NAND and inverter have the same logic but using only 4 inverters means just 1 74HC05 is needed and the 11 NAND gates can be accommodated on 3 of the 74HC03's, right? As for the select logic, if we go with the 2 joystick option, could we use the 12th NAND gate on the 3rd 74HC03 to simulate the 74HC04 inverter? Meaning we could just pass the select line (after a 1M pull up resister) for selecting Joystick 1 and the inverted value from the NAND gate to select Joystick 2? I would like to add some NAND gates to my order before I checkout; is this one okay? Thanks again! John
  15. Thanks, I figured that symbol was another capacitor but the 10/16 threw me off a bit. Excellent! I have these in my shopping cart @ Mouser; I'll wait a bit in case we end up adding a few more items based on your 'crazy' design above Although that sounds tempting and very interesting, I think we should keep it simple with just 2 joysticks as the logic involved for selecting/etc. gets a bit complicated. Our plan is to allow 4 joysticks on 2 ports by basically using a 2-joystick selector adapter on each port. Of course that means we can't use a Savekey/etc. in the right joystick port, but that should be fine since the pros (simpler circuit, easier to read and confirm values for each player, less ROM needed, less time needed in vblank/overscan etc.) outweigh the cons. So, with an adapter connected into each port, for 4 player games we can detect if there is an adapter in each port (INPT1=1, INPT0=0 if an adapter is in the left port and INPT3=1, INPT2=0 if an adapter is in the right port). Also, we use just one write to VBLANK to read two joysticks, one on each port: DUMP_PORTS=0 you can read Joystick 1/Joystick 3 movement in SWCHA, Joystick 1 button/Joystick 3 button in INPT4 and INPT5 respectively DUMP_PORTS=1 you can read Joystick 2/Joystick 4 movement in SWCHA, Joystick 2 button/Joystick 4 button in INPT4 and INPT5 respectively Perhaps down the road we can design a 4 joystick adapter on 1 port; that would be a cool project! Thanks again for all the help! John
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