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Parallel flash? — Parallax Forums

Parallel flash?

VaatiVaati Posts: 712
edited 2010-02-08 00:56 in Propeller 1
Has anyone managed to interface parallel flash/eprom to the prop?· I need code...

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Comments

  • Mike GreenMike Green Posts: 23,101
    edited 2010-02-07 22:13
    There's not much point. Flash is commonly used to provide very large memory spaces and that would take too many I/O pins to be useful if using a parallel interface. EPROM or EEPROM is similar and there are very nice SPI interface EEPROMs and flash memory that only take a few I/O pins. You will find parallel interface SRAM interfaces because that's handy for emulators like the RamBlade and Zicog for the raw speed, but you can't get the speed with flash. Sounds like a class project ...
  • VaatiVaati Posts: 712
    edited 2010-02-07 22:15
    Well, it is actually for a reprogrammable gameboy cartridge:

    http://gameboyprogramming.blogspot.com/

    There's my small blog with some pictures.

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  • VIRANDVIRAND Posts: 656
    edited 2010-02-07 22:24
    It is very easy but uses up lots of pins.
    Pins can be saved with shift registers but that is a slowdown.
    Latches are faster, giving 8 bits at a time.
    For EPROM, such as UV eraseable, well, all mine are common ones that use 5V so you will need resistors on Axx and Dx.
    Ground VSS, /OE, /CE, see data sheets for others such as VPP.
    VCC to 5V.
    A0-A15 most simply requires 16 pins in case of 27C512. (other sizes ... more or less pins)
    D0-D7 most simply requires 8 pins in case of 27C512
    Simply OUTA the address to read on the A0-Axx pins.
    Delay with a repeat 100 or something like that.
    Simply INA the D0-D7 pins to read the data.

    That all implies that the EPROM has already been programmed.
    If you are building an EPROM programmer, you need to know the specs of each one you plan to program.
    You will need a programmable power supply that has 0V,5V, maybe 6V for fast program, and 12V,21V, 25V
    (although erom programming voltages higher than 12V are very old, such as 27128,2764,2732,2532,2716.)
    If you are building an eprom programmer you can save lots of Axx pins by binary counters 4040,
    but deja-vu, someone mentioned that recently. Other sequential uses may find that convenient also.
    The pin order should be the same for P0-Px as for A0-Ax and D0-Dx unless you want to scramble your code,
    like the Propeller Interpreter ROM is scrambled.

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    I should be typing in Spin now.
  • VaatiVaati Posts: 712
    edited 2010-02-07 22:30
    Ok--thanks! I don't care about pin usage, because the only things that I will need will be the external EEPROM pins, the 29 Gameboy cartridge pins, and the two serial communication pins.

    So, what would my code look like?

    I have code in hex for the AVR that reads and writes gb carts, so I might have to convert that to asm and then pasm...

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    Quit buying all those fixed voltage regulators, and·get an Adjustable Power Supply·for your projects!· Includes an LED testing terminal!

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  • VIRANDVIRAND Posts: 656
    edited 2010-02-07 22:30
    Vaati said...
    Well, it is actually for a reprogrammable gameboy cartridge:

    http://gameboyprogramming.blogspot.com/

    There's my small blog with some pictures.

    Consider putting all your ROMS on SD card and using Propeller to emulate the cartridge? (maybe irrelevant idea.)

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    I should be typing in Spin now.
  • VaatiVaati Posts: 712
    edited 2010-02-07 22:32
    Yeah--that is one thing that I have been thinking about.... That is probably the best possible solution, not to mention a perfect product idea...

    It would probably be pretty easy too.

    Can external chips write to the prop's ram?

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    Quit buying all those fixed voltage regulators, and·get an Adjustable Power Supply·for your projects!· Includes an LED testing terminal!

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  • VIRANDVIRAND Posts: 656
    edited 2010-02-07 22:41
    Vaati said...
    Yeah--that is one thing that I have been thinking about.... That is probably the best possible solution, not to mention a perfect product idea...

    It would probably be pretty easy too.

    Can external chips write to the prop's ram?

    Only if there is a RESET and Prop tries to boot the Prop Plug or its own EEPROM,
    while those pins are in use by the game system.
    UNLESS YOU PROGRAM THAT FEATURE ON PURPOSE.

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    I should be typing in Spin now.
  • VaatiVaati Posts: 712
    edited 2010-02-07 22:43
    Ok--I think that my best bet is to just go with another chip...

    So, can the prop write more than 32k ram data?

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    Quit buying all those fixed voltage regulators, and·get an Adjustable Power Supply·for your projects!· Includes an LED testing terminal!

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  • jazzedjazzed Posts: 11,803
    edited 2010-02-07 22:47
    Mike Green said...
    There's not much point. ...
    Agreed up to a certain "point". However, if you have a C compiler that puts non-self-modifying code in flash (.text) and keeps variable references in .data section, Flash could be useful. The number of pins available and other junk like performance and onboard RAM are constantly issues though. Yes, use a more Flash friendly chip.
  • Dr_AculaDr_Acula Posts: 5,484
    edited 2010-02-07 22:51
    I was going to suggest getting a Willem eprom/eeprom programmer (they are pretty cheap on ebay - probably less than a propeller+board+support chips), but then thinking about Virand's post more, and thinking what can be done with one of the prop designs that uses sd card, you could build a standalone emulator.

    Certainly the prop can write more than 32k - you just need to add latches to talk to all the address pins. Cluso's ramblade and my dracblade can talk to 512k but with minor mods can do more - eg 32 bit addresses if you used all 4 of the 8 bit latches latches on the dracblade which is 2^32 and is far more than any eeproms out there.

    There would be many solutions to this problem. Certainly worth brainstorming a bit more before deciding what to do.

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  • VaatiVaati Posts: 712
    edited 2010-02-07 22:54
    http://devrs.com/gb/files/mbc1.gif


    That is basically what I am trying to make, except the ROM would be replaced with flash or an SD card and the ram would be bigger. The prop would take the place of the chip labeled "MBC1."

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    Quit buying all those fixed voltage regulators, and·get an Adjustable Power Supply·for your projects!· Includes an LED testing terminal!

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  • VIRANDVIRAND Posts: 656
    edited 2010-02-07 22:55
    The Prop has 32K RAM inside of it. It can access more outside of it.
    Unless games cartridges have more than 32K RAM in them I don't know what you are asking,
    I'm guessing you need to cache the game ROMs in RAM while they are being played.
    I don't know if that is necessary or a problem since it depends on maximum access times.

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    I should be typing in Spin now.
  • Peter JakackiPeter Jakacki Posts: 10,193
    edited 2010-02-07 22:58
    If you do interface to parallel Flash it's not as simple as adding resistors to the pins. Every pin except the data lines are inputs on the Flash so you don't need resistors (what are they going to limit?) but you may need level shifters so 74HCT latches can run from 5V and accept Prop levels as inputs. Going slightly OT but whenever I read threads that talk about expanding the memory space I keep thinking "It's a microcontroller, it's a microcontroller". It's way easier to team up the Prop with say an ARM chip (which have good C compilers) that can address a large memory space very easily and faster than a Prop can execute one PASM instruction. Not as much fun, but the alternatives are ugly kludges.

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    *Peter*
  • VaatiVaati Posts: 712
    edited 2010-02-07 23:01
    Okay--I think that an SD card would be my best bet, so I am going to ditch the flash idea.

    Also, a 16MB flash chip is about as expensive as a 2GB SD card. So, SD is definitely best.

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    Quit buying all those fixed voltage regulators, and·get an Adjustable Power Supply·for your projects!· Includes an LED testing terminal!

    (no longer new) SD Card Adapter·Now available!· Add extra memory to your next Propeller project with ease!
  • MicrocontrolledMicrocontrolled Posts: 2,461
    edited 2010-02-07 23:10
    So you've given up on the Hydra, huh?

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    Computers are microcontrolled.

    Robots are microcontrolled.
    I am microcontrolled.

    SX Spinning light display·

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  • VaatiVaati Posts: 712
    edited 2010-02-07 23:41
    No! I haven't given up--I am also trying to emulate the gameboy on the prop using a Z80 emulator program, seeing as the gameboy emulates the Z80.

    The hydra has just taken a back seat for now. [noparse]:)[/noparse]

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    Quit buying all those fixed voltage regulators, and·get an Adjustable Power Supply·for your projects!· Includes an LED testing terminal!

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  • Dr_AculaDr_Acula Posts: 5,484
    edited 2010-02-08 00:14
    Looking at that schematic - 16 addres, 8 data, 4 other lines = 28. Prop has 32 and 2 are spoken for with eeprom so that only leaves two lines free. SD needs just a few more than that. But with some cunning sharing it could be done I'm sure.

    Prop could be chugging away in the background polling for a ram 'read' or a ram 'write' and then if you have preloaded the data off the sd card into hub ram, it might just be possible to get it out onto the data lines quick enough.

    But more information might reveal even better solutions. Eg, what are those 32 lines connected to?

    More broadly speaking - gameboy on the prop? Well, that could be a worthy task!

    Immediate problem - all the 8080 opcodes are emulated but not every single Z80 code. So it might be helpful to see what gameboy source code looks like.

    And then there is the graphics issue - the Z80 emulation fits in a cog, but when you add some driver code for input (keyboard/keypad), sd card, display etc, it uses a lot of hub ram, and that eats into ram available for graphics. Everything is a compromise and a lot of things only just fit. So with a text display you need 80x40 bytes =3200 bytes. That won't display much for a game.

    It may end up a two prop solution with one prop devoting virtually all its hub ram to graphics.

    Thinking of hardware, Cluos's triblade may be the best bet and use two props??

    But it would be worth checking first what opcodes the gameboy uses as that could hold things up a lot if you have to ask heater to add more opcodes (which is entirely possible as I've done a few, but extremely tedious). Do you have access to a schematic for the gameboy in question, plus some demo code?

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  • VaatiVaati Posts: 712
    edited 2010-02-08 00:34
    Hahaha!! I am glad you asked for more gameboy info, because I have it ALL!!! smile.gif

    At least, http://www.devrs.com/gb/ does...

    gameboy schematic- what "those 32 lines are connected to"

    http://devrs.com/gb/files/gameboy1.gif


    Look around devrs.com for a load of gameboy info and links, and check out http://www.reinerziegler.de/readplus.htm for a lot of hardware info.

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    Quit buying all those fixed voltage regulators, and·get an Adjustable Power Supply·for your projects!· Includes an LED testing terminal!

    (no longer new) SD Card Adapter·Now available!· Add extra memory to your next Propeller project with ease!
  • VIRANDVIRAND Posts: 656
    edited 2010-02-08 00:43
    I was just going to say, doesn't the Gameboy have a bent z80 with two opcodes reversed?
    I guess no worry, someone has it all under control.
    oops: wrong thread, here is what I was talking about:
    http://forums.parallax.com/showthread.php?p=879537

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    I should be typing in Spin now.
  • VaatiVaati Posts: 712
    edited 2010-02-08 00:50
    So...

    The Prop might be able to take down the gameboy! It might be able to read carts and play them, and emulate the cartridge processes themselves! This would make an awesome prop design contest entry if it all works... smile.gif

    The one problem I can think of with using an SD card is that some of the rom pins in a non-modded gameboy cart are connected to the SRAM... But, I suppose that the prop would really be converting the SD memory to a compatible replacement for the original rom, so it would work out.

    I think that the problem is going to be I/O. I may need to stick in another small mcu to do some stuff. The SX might do the job...

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    Quit buying all those fixed voltage regulators, and·get an Adjustable Power Supply·for your projects!· Includes an LED testing terminal!

    (no longer new) SD Card Adapter·Now available!· Add extra memory to your next Propeller project with ease!
  • Cluso99Cluso99 Posts: 18,069
    edited 2010-02-08 00:51
    Here's an idea - use a RamBlade, add wires from the SRAM to the GameBoy connector. The load the required program from uSD into SRAM, send the prop to sleep, run the GameBoy.

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    Links to other interesting threads:

    · Home of the MultiBladeProps: TriBlade,·RamBlade,·SixBlade, website
    · Single Board Computer:·3 Propeller ICs·and a·TriBladeProp board (ZiCog Z80 Emulator)
    · Prop Tools under Development or Completed (Index)
    · Emulators: CPUs Z80 etc; Micros Altair etc;· Terminals·VT100 etc; (Index) ZiCog (Z80) , MoCog (6809)·
    · Prop OS: SphinxOS·, PropDos , PropCmd··· Search the Propeller forums·(uses advanced Google search)
    My cruising website is: ·www.bluemagic.biz·· MultiBlade Props: www.cluso.bluemagic.biz
  • VaatiVaati Posts: 712
    edited 2010-02-08 00:56
    Hmmm... I may want to market this though, and I definitely want it the size of the gameboy cartridges...

    EDIT:·I checked the ramblade topic--that thing is tiny!· Can I have the board·files, or if possible, the reverse board image so I can iron it to a pcb?

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    Quit buying all those fixed voltage regulators, and·get an Adjustable Power Supply·for your projects!· Includes an LED testing terminal!

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    Post Edited (Vaati) : 2/8/2010 1:16:17 AM GMT
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