Search found 26 matches

by doragasu
Mon Jul 30, 2018 12:59 pm
Forum: Homebrew Projects
Topic: New Game for the Game Boy: INTO THE BLUE
Replies: 29
Views: 12050

Re: New Game for the Game Boy: INTO THE BLUE

If anyone is curious, here is a render of the cartridge design, and a photograph of the programmer and a prototype assembled (excepting the SRAM and the battery circuit).

Image Image
by doragasu
Mon Jul 30, 2018 1:00 am
Forum: Homebrew Projects
Topic: New Game for the Game Boy: INTO THE BLUE
Replies: 29
Views: 12050

Re: New Game for the Game Boy: INTO THE BLUE

I have my own cartridge design with 8 MiB of Flash, 128 KiB of SRAM (battery backed) and a working implementation of the MBC5 mapper. I have also a USB programmer designed to burn the cartridges. This should cover with ease all the needs of any homebrew GB/GBC game!
by doragasu
Sat Jun 03, 2017 2:45 pm
Forum: NESdev
Topic: New, homebrew mapper
Replies: 15
Views: 6421

Re: New, homebrew mapper

Thanks for the suggestions! As na_th_an wrote, the hardware already exists. It uses a CPLD and I already implemented and MMC3 clone. But we are coding another mapper because for some games they want to develop, it is more convenient to change complete 32KiB/8KiB PRG/CHR blocks. Here is the cart and ...
by doragasu
Sun Apr 24, 2016 1:42 pm
Forum: NES Hardware and Flash Equipment
Topic: Expansion port on 72 pin cart connector. Has it been used?
Replies: 5
Views: 1925

Re: Expansion port on 72 pin cart connector. Has it been use

Thanks for the fast and complete answer! It looks like as long as I do not use EXP 0, 2, 5, 6 and 9, there should be no problem.
by doragasu
Sun Apr 24, 2016 10:16 am
Forum: NES Hardware and Flash Equipment
Topic: Expansion port on 72 pin cart connector. Has it been used?
Replies: 5
Views: 1925

Expansion port on 72 pin cart connector. Has it been used?

While designing my MMC3 cart I thought of using the pins of the expansion port (16 ~ 20 and 51 ~ 55) for the CPLD JTAG port and the #WE of the flash chips. But I don't know if these pins are used by any peripherals that might make my cart go nuts.

Any info about this?
by doragasu
Thu Apr 21, 2016 11:47 pm
Forum: NES Hardware and Flash Equipment
Topic: What acknowledges MMC3 IRQ?
Replies: 13
Views: 4513

Re: What acknowledges MMC3 IRQ?

I understand. I suppose the only way of making sure is testing. So I'll continue designing the PCB and test it when it's finished. I hope I need not to change it, because doing so would complicate things a bit.

Again, thanks for the tips!
by doragasu
Tue Apr 19, 2016 12:52 pm
Forum: NES Hardware and Flash Equipment
Topic: What acknowledges MMC3 IRQ?
Replies: 13
Views: 4513

Re: What acknowledges MMC3 IRQ?

Thanks for taking the effort of interpreting the waves and making corrections! Although it doesn't look like on the simulation, IRQ is asserted when PPU A12 rises. It doesn't look like because it's delayed one M2 clock cycle. This causes it to fire when PPU A12 is lowered on the simulation, even tho...
by doragasu
Tue Apr 19, 2016 5:54 am
Forum: NES Hardware and Flash Equipment
Topic: What acknowledges MMC3 IRQ?
Replies: 13
Views: 4513

Re: What acknowledges MMC3 IRQ?

Finished implementation and simulation. If I understood properly MMC3 documentation, I think everything should run fine. Here are the simulation results: http://i.imgur.com/1Nl2XUx.png http://i.imgur.com/BmDrNOd.png Just in case anyone is wondering, here is the port mapping: http://i.imgur.com/ahhLV...
by doragasu
Thu Apr 14, 2016 1:22 am
Forum: NES Hardware and Flash Equipment
Topic: Boot timing
Replies: 5
Views: 1899

Re: Boot timing

lidnariq wrote:In my experience, the voltages stabilize close to 0.1 seconds before the CPU is released from reset... but you really should double check. (I've only got my two NES-CPU-07 boards to test with)
Didn't see this post. If the value is correct, 0.1 s should be a lot more than enough, thanks!
by doragasu
Thu Apr 14, 2016 1:15 am
Forum: NES Hardware and Flash Equipment
Topic: Boot timing
Replies: 5
Views: 1899

Re: Boot timing

@krzysiobal I have checked so far 2 CPLDs: - Xilinx XC2C128: 350 us configuration time (from datasheet). - Lattice LCMXO256C: I have not found the exact number. Family datasheet states it "boots in microseconds", but I haven't found how many. Wake from sleep timing for this CPLD is 400 us, so I assu...
by doragasu
Wed Apr 13, 2016 12:52 pm
Forum: NES Hardware and Flash Equipment
Topic: Boot timing
Replies: 5
Views: 1899

Boot timing

While designing my MMC3 clone, I have noticed CPLDs have a relatively high configuration time (for a 128 macrocell density one, it's about 400 us). So I was wondering if they will be fast enough to be operative when the console starts requesting data... So the question is... how much time do I have ...
by doragasu
Wed Apr 13, 2016 12:31 am
Forum: NES Hardware and Flash Equipment
Topic: Will this mapper 113 implementation work?
Replies: 18
Views: 8540

Re: Will this mapper 113 implementation work?

You are right, I have nothing to gain on this PCB, but was asking just in case I decide to do a future revision (or just for learning purposes). But maybe it's better to be safe and leave it as is.

Thanks for feedback!
by doragasu
Tue Apr 12, 2016 1:02 am
Forum: NES Hardware and Flash Equipment
Topic: Will this mapper 113 implementation work?
Replies: 18
Views: 8540

Re: Will this mapper 113 implementation work?

I already got the PCBs for the first approach (didn't have time to implement the improvements yet) and they work perfect! http://i.imgur.com/1Fp0SSM.jpg But suddenly I noticed something more that could be optimized: even though the boards work, shouldn't they also work without using Phi2? (since #PR...
by doragasu
Tue Apr 12, 2016 12:48 am
Forum: NES Hardware and Flash Equipment
Topic: What acknowledges MMC3 IRQ?
Replies: 13
Views: 4513

Re: What acknowledges MMC3 IRQ?

I already saw the FunkyFlashCart, but AFAIK sources are in "schematic" format, not HDL (or at least I could only find schematics).

About the clocks, I gave it another thought and you might be right, M2 should be enough since it's frequency is much higher than "PPU A12 frequency".

Again, thanks!