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Interfacing with FRAM — Parallax Forums

Interfacing with FRAM

XanfarasXanfaras Posts: 7
edited 2010-02-12 16:58 in BASIC Stamp
Hello all,
I have a FRAM chip that I am trying to use for data storage with my BS2, but I am unsure of how to do so properly. The data sheet is attached, but I am unsure of what commands to send it. I believe I have everything wired correctly. I have pins 1-4 grounded, 5 and 6 are wired to I/O pins on the stamp (9 and 8, respectively), 7 is unconnected, and 8 is set to ~3V.

Right now, I am just trying to get a simple program to write data and read it back. If anyone has any advice or could point me in the right direction, it would be most appreciated.

Thanks,
Xan
pdf
pdf
FRAMDataSheet.pdf
125K

Comments

  • FranklinFranklin Posts: 4,747
    edited 2010-02-12 15:45
    Looks like you have it connected correctly. Could you attach the code you are trying to use to your next post?

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    - Stephen
  • Mike GreenMike Green Posts: 23,101
    edited 2010-02-12 15:51
    You will have trouble using this FRAM with a Stamp because the FRAM is a 3.3V part and the Stamp is a 5V part. The Stamp's 5V logic signals can destroy the FRAM's I/O pin structures and the 3.3V logic signals may not be read properly by the Stamp's I/O pins. In the Propeller forum, in one of the "sticky" threads at the top of the thread list, there's a long thread on connecting 3.3V and 5V parts together. Pretty much everything that applies to hooking the 3.3V Propeller to 5V devices also applies to what you want to do. There are some specific interfaces described for I2C interfaces which is what you've got with the FRAM.

    You would be much better off getting a 5V FRAM part if you can. The interfacing for a 3.3V part isn't difficult, but you could avoid it and concentrate on the software.

    There are several Nuts and Volts Columns on interfacing EEPROMs and other I2C devices to a BS2p or BS2. The column for the BS2 includes sample code that you could use.
  • XanfarasXanfaras Posts: 7
    edited 2010-02-12 15:52
    Well that's just it, actually. I'm not really sure where to start. I was hoping someone here might help give me a basis.
  • XanfarasXanfaras Posts: 7
    edited 2010-02-12 15:53
    Thanks Mike, I will take a look at what you posted. Hopefully that will help.
  • Mike GreenMike Green Posts: 23,101
    edited 2010-02-12 16:58
    Try Nuts and Volts Column #85. It gives sample code for non-EEPROM I2C devices, but has all the basic routines you'll need to substitute for the BS2p's built-in I2C statements.
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