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Reading parallel memory? — Parallax Forums

Reading parallel memory?

VaatiVaati Posts: 712
edited 2010-03-18 22:59 in General Discussion
Not sure what can do this, so I'm just putting it in the sandbox...

Is the BS2, prop, or SX able to read a parallel memory device such as a flash memory chip or a UV EPROM and send the data to a computer? This is very important for a lot of my current projects...

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Comments

  • kwinnkwinn Posts: 8,697
    edited 2010-03-17 22:52
    Yes. As long as you can provide an address and OE signal the chip will output the data at that address.
  • VaatiVaati Posts: 712
    edited 2010-03-17 22:53
    Ok--so can the SX do this? I haven't done much SX stuff, but I would like to... The only thing that it might need is more I/O...

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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!
  • PJAllenPJAllen Banned Posts: 5,065
    edited 2010-03-17 23:26
    Depends on the number of address bits and data bits.·
    If you run short of I/O then it's Shift Register Time.
  • MicrocontrolledMicrocontrolled Posts: 2,461
    edited 2010-03-18 00:33
    A shift register would be the easiest.

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  • MicrocontrolledMicrocontrolled Posts: 2,461
    edited 2010-03-18 00:34
    Oh, and I think that you should use a propeller if a shift register is not what you had in mind. Propeller.gif

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    Don't click on this.....

    Use the Propeller icon!! Propeller.gif
  • kwinnkwinn Posts: 8,697
    edited 2010-03-18 03:21
    Two '595's and a 597 would let you read out any 8 bit wide eprom up to 64KB. Propeller is even easier 24 2K2 resistors for 64Kx8.
  • VaatiVaati Posts: 712
    edited 2010-03-18 21:26
    What about an eprom greater than 64KB, like 256KB or more? Is the prop able to do that?

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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!
  • Chris SavageChris Savage Parallax Engineering Posts: 14,406
    edited 2010-03-18 22:08
    Vaati,

    It's really not a matter of the size per se...as mentioned above, you can use shift registers. In the example of a BASIC Stamp reading a 64KB EEPROM you would use two 74HC595 and one 74HC165 shift register. /OE would go to ground but you would need the /CS line, so all things considered you would need 5 I/O pins to make this happen. Now, as the EEPROM gets larger it uses more address lines (possibly my data lines too if more then 8-bits wide). So now all you do is add more shift registers as needed. These consume no additional I/O pins from the microcontroller. The limiting factor now is does your microcontroller have enough memory to shift out and xx-bit address and receive the xx-bit data value back? If so, then you're set. While the BASIC Stamp only has 16 bit registers, you could simulate 32-bit address generation very easily, meaning the BASIC Stamp 2 could read an EEPROM with 4294967296 bytes, one at a time.

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    Chris Savage

    Parallax Engineering
    ·
  • VaatiVaati Posts: 712
    edited 2010-03-18 22:59
    Ok. I will keep this in mind for a future project... smile.gif

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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!
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