SainT Posted July 25, 2014 Author Share Posted July 25, 2014 (edited) Well, I can certainly say that any kind of EEPROM compatibility is not going to happen, I'm afraid. I'm designing this with expandability in mind rather than trying to simulate the very few save options already out there. It should be pretty simple to patch ROMs to use an alternative load / save method though (as you find on Gameboy flash carts etc). What you will be able to do however is read and write as much data as you like on the memory card, so it does open up many more possibilities than a simple EEPROM type save. Edited October 25, 2019 by SainT Quote Link to comment Share on other sites More sharing options...
SainT Posted July 27, 2014 Author Share Posted July 27, 2014 Bit of an update -- finally got some time to look at the routing tonight. Redid most of it again as I realised it wasn't going to work and I'm finally getting somewhere now. The majority of the work is done in routing all the components together and just a few control signals need adding before routing all the signals from the Lynx cart edge. That's the easy part as there is tons of space available where you cant place components. Its been relatively tricky (for me anyway!) to route as the space is so limited on the Lynx cart for all the components needed, plus you cant put decoupling caps on the back of the board as is usually my habit. Still, fun though! 1 Quote Link to comment Share on other sites More sharing options...
SainT Posted July 31, 2014 Author Share Posted July 31, 2014 Nearly complete... 3 Quote Link to comment Share on other sites More sharing options...
Guitari Posted July 31, 2014 Share Posted July 31, 2014 Any recommendations as to what SD card to get? Quote Link to comment Share on other sites More sharing options...
obschan Posted July 31, 2014 Share Posted July 31, 2014 Could you add a hole or something, so it could removed easily from a lynx 1? Quote Link to comment Share on other sites More sharing options...
venom4728a Posted July 31, 2014 Share Posted July 31, 2014 Please count me in for one also, Tell me when and where to send my money!! Robert Quote Link to comment Share on other sites More sharing options...
Greg2600 Posted August 1, 2014 Share Posted August 1, 2014 Could you add a hole or something, so it could removed easily from a lynx 1? Might not be so easy to get out of a Lynx II either! Any recommendations as to what SD card to get? Just get a cheap SDHC microSD card. 4GB versions are dirt cheap now. They are normally made by Sandisk. 1 Quote Link to comment Share on other sites More sharing options...
+karri Posted August 2, 2014 Share Posted August 2, 2014 Nice routing btw. You have done this before... I also agree that eeprom use is not so important. If you want it you can use the real cart. Eeproms can not be shared between the carts. Quote Link to comment Share on other sites More sharing options...
SainT Posted August 2, 2014 Author Share Posted August 2, 2014 (edited) Any memory card should do the job in theory, although once I've got something working I'll post up which ones I can confirm to work. Never can be 100% sure on SPI compatibility... I have no idea about Lynx 1 compatibility as I just have a couple of Lynx 2's. Not sure what the space is like in the cartridge bay. Once I've got a prototype up and running I'll see if I can pick up a cheap Lynx 1 and see. As for holes in general I could probably put one above the memory card connector. It's layed out like it is with a cutout so I can fit 2 pcb's on a single 10x10 board, meaning the pcb cost is halved. We'll see how it goes. Thanks, Karri. I've done a few boards before, but I'm very much a novice with hardware. The layout has ended up being relatively tidy thanks to the peripheral pin select on this PIC chip and the flexibility you have with SRAM pins. I think I'll tweak the routing a bit to try and tidy up the ground plane, though. I'd normally have power on the top and ground on the bottom, but this layout is really tight so power and ground are on the bottom. I'm at the limits with trace and via size with the PCB fab so I'm hoping it'll all come out alright. Edited October 25, 2019 by SainT 1 Quote Link to comment Share on other sites More sharing options...
SainT Posted August 7, 2014 Author Share Posted August 7, 2014 Pretty much final routing. Just need to sanity check everything then I'll order the components and do a dry run fitting on a printout. If all is well I'll order some PCB's! Getting closer... 5 Quote Link to comment Share on other sites More sharing options...
LX.NET Posted August 7, 2014 Share Posted August 7, 2014 Very impressive. This electronic wizardry absolutely baffles me. It seems easier to emulate in code than to build it for real. (says the an-electro-betic developer) 1 Quote Link to comment Share on other sites More sharing options...
djrodderz Posted August 8, 2014 Share Posted August 8, 2014 Brilliant, Keep us all updated! Quote Link to comment Share on other sites More sharing options...
+karri Posted August 8, 2014 Share Posted August 8, 2014 Have you given any thought for save games? In MegaPak we reserved a 32 byte memory area for EEPROM saves. The idea was to read it from the EEPROM into RAM at startup. And write if from RAM to EEPROM whenever it changed due to a new high score or something. In Handy the read/write did not work so you lost progress when you turned the game off. But as long as you were playing the EEPROM appeared to be working as the content was in a RAM buffer. Perhaps you could think about some similar functions for the SD card. We could add it to cc65. You could then link your game either with EEPROM support or SD card support. Quote Link to comment Share on other sites More sharing options...
SainT Posted August 8, 2014 Author Share Posted August 8, 2014 (edited) On 8/8/2014 at 12:44 PM, karri said: Have you given any thought for save games? In MegaPak we reserved a 32 byte memory area for EEPROM saves. The idea was to read it from the EEPROM into RAM at startup. And write if from RAM to EEPROM whenever it changed due to a new high score or something. In Handy the read/write did not work so you lost progress when you turned the game off. But as long as you were playing the EEPROM appeared to be working as the content was in a RAM buffer. Perhaps you could think about some similar functions for the SD card. We could add it to cc65. You could then link your game either with EEPROM support or SD card support. Yep, I intend to have file read / write access to the memory card. So save games will be upto the game to load and save state from the card. Edited October 25, 2019 by SainT 1 Quote Link to comment Share on other sites More sharing options...
Lynxpro Posted August 8, 2014 Share Posted August 8, 2014 Very cool project! Glad to see people still have an interest in designing cool hardware to work with this awesome handheld. I would agree with several others in this thread that compatibility with EEPROM saves on a handful of known cartridges (SIMIS, MegaPak, etc.) would be ideal. This would also cultivate a standard for future homebrewers to use, and would allow them to create a physical cart with a 93c86 on it, or use the multi-cart, and not have to make two versions of their game. Next project for you: a ComLynx to WiFi or Bluetooth adapter, so we can get rid of all those pesky cables... I'd rather some ComLynx to JagLink or MIDI adapter cables were made. Wouldn't it be a sight to have STs, A8s, Lynxes, and Jaguars linked up and playing MIDI Maze together [assuming the game was ported to the Lynx and the Jaguar]... Quote Link to comment Share on other sites More sharing options...
Joe Stella Posted August 14, 2014 Share Posted August 14, 2014 I'm in. Quote Link to comment Share on other sites More sharing options...
HtheB Posted August 15, 2014 Share Posted August 15, 2014 Count me in aswell!!! Quote Link to comment Share on other sites More sharing options...
Rick Dangerous Posted August 16, 2014 Share Posted August 16, 2014 Cool, stoked to get this bad boy! Hope I'm still on the list Quote Link to comment Share on other sites More sharing options...
+Stephen Posted August 17, 2014 Share Posted August 17, 2014 Looks killer - I'd like one for sure. Quote Link to comment Share on other sites More sharing options...
Guitari Posted August 22, 2014 Share Posted August 22, 2014 Hi SainT, I think I remember you saying that you weren't specifically trying to get the card working with homebrew ROMs, but how will it be with openly available homebrew ROMs like Gadget's progressive versions of Alien for example? cheers, 1 Quote Link to comment Share on other sites More sharing options...
TXG/MNX Posted August 24, 2014 Share Posted August 24, 2014 I want atleast two of those Quote Link to comment Share on other sites More sharing options...
imstarryeyed Posted August 25, 2014 Share Posted August 25, 2014 Wow great project I am so in for one for my lynx 1 Quote Link to comment Share on other sites More sharing options...
JagLynx4Life Posted August 26, 2014 Share Posted August 26, 2014 Great news! I'm down for 2 Quote Link to comment Share on other sites More sharing options...
SainT Posted August 26, 2014 Author Share Posted August 26, 2014 (edited) On 8/22/2014 at 8:20 PM, Guitari said: Hi SainT, I think I remember you saying that you weren't specifically trying to get the card working with homebrew ROMs, but how will it be with openly available homebrew ROMs like Gadget's progressive versions of Alien for example? In theory it should actually run pretty much any homebrew, as I am also supporting bank switching using the audin pin as is used by some of the homebrew. It will either be memory card file access support (which also uses the audin pin) OR 1mb bank switching. It will be dependant on the ROM image. The one thing I am specifically not supporting is any emulation / compatibility with EEPROM save or anything like that used by other carts. Edited October 25, 2019 by SainT 1 Quote Link to comment Share on other sites More sharing options...
SainT Posted August 26, 2014 Author Share Posted August 26, 2014 A very short update as well... I've done a bit more on the routing and I think finalised everything. I've had bugger all spare time recently, but next on the list is to write the PIC code for programming the SRAM as a way of sanity checking I've hooked everything up right. There's nothing like actually writing the code which drives all the lines to figure out if its correct. 3 Quote Link to comment Share on other sites More sharing options...
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