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RAM RAM RAM how much do you need? - Page 3 — Parallax Forums

RAM RAM RAM how much do you need?

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Comments

  • mctriviamctrivia Posts: 3,772
    edited 2009-12-12 06:28
    I meant I have nothing to do with there sales and distribution. Not that I had nothing to do with its development.

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    24 bit LCD Breakout Board now in. $21.99 has backlight driver and touch sensitive decoder.
  • grins73grins73 Posts: 17
    edited 2009-12-12 07:02
    hi there!!

    ·········· So what ever to this project?? im fairlt new to the prop chip but I can see I will need more ram in the not to·distant·future. I would be happy with like 256K or somthing though, hell I couldnt see my self even useing past one meg, specially when you have·that nice little SD card·plug in. I would love a little kit that·can plug in to a bread bord, or even a bagy of chips that you can plug in to a bread bord your self to teach you how writing to an external ram chip is done.



    Dose any one know how much ram the prop 2 will have?
  • mctriviamctrivia Posts: 3,772
    edited 2009-12-12 07:16
    test rig built. short 4 pins but luckily it will work without 4 pins(1x 3.3V, 1x 1.8V, 2x VSS) I would prefer all pins but this will simulate worst case.

    The prop2 will have 300k or so RAM.

    You can do 256k RAM with a relitevely inexpensive SRAM chip and 2x 74HC573N

    on a bread board you would not be able to run it at high speeds though because of poor connections and terible EMI.

    I went with 8MW because it has a good price point and it is always good to shoot for higher then lower. Cutting the amount of RAM in half would save only a few dollars and would make it much more expensive for those that do need it.

    I have plans to utilize a large portion of 1 of these modules to do high res 16bit colour with a large number of movable transparent sprites. What you plan to do with them is up to you.

    ▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
    24 bit LCD Breakout Board now in. $21.99 has backlight driver and touch sensitive decoder.
    1272 x 972 - 259K
    1773 x 1062 - 360K
  • mctriviamctrivia Posts: 3,772
    edited 2009-12-13 08:05
    it is late and I have to get some sleep but after assembling and testing a few modules i have yet to have one pass and I am thinking it is due to a software error. I know my code will properly set the latches to the correct address. am I missing something for what is needed for simple reading and writing to the module?

    i know it is ineficient but I am just looking for working at the moment. I am using the following to read the ram value:

      'Get value
      DIRA[noparse][[/noparse]7..0]~ 'set to input
      OUTA[noparse][[/noparse]20]:=1 'CS active 
      OUTA[noparse][[/noparse]18]:=0 'RE active
      value:=INA[noparse][[/noparse]7..0]
      OUTA[noparse][[/noparse]18]:=1 'RE deacvtive
      OUTA[noparse][[/noparse]20]:=0  'CS deactive
    
    

    ▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
    24 bit LCD Breakout Board now in. $21.99 has backlight driver and touch sensitive decoder.
  • jazzedjazzed Posts: 11,803
    edited 2009-12-13 08:55
    You need to re-seed your pseudo random variable "y:=5" before read-back. Guessing at your schematic, I don't see any other problems.
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