Shop OBEX P1 Docs P2 Docs Learn Events
Multiple EEPROMs for one Stamp? — Parallax Forums

Multiple EEPROMs for one Stamp?

Velvet LeopardVelvet Leopard Posts: 47
edited 2004-08-14 01:48 in BASIC Stamp
Hewwo, all.· I had the near miraculous chance of getting some free EEPROM chips.· 5 of them.· They are al 25LC640 I/P094 chips.· I learned how to wire ONE of them to a basic stamp II.· I am still struggling with the code to use them.· What I want to know is if there was a ligitimate reason to need more than one of these EEPROMs for one stamp, how would you wire them all up?· I couldn't see how you could just add them and take up all the I/Os.· Any help?

Comments

  • Jon WilliamsJon Williams Posts: 6,491
    edited 2004-08-13 13:18
    I looked at the data sheet very quickly and believe you can. You just need to have separate chip select lines for each of the devices you want to connect; the other lines can be shared. You can even connect the SI and SO lines for each device together, but for saftey you'll want to do it through a 1K resistor. With this scheme, you could connect to three devices with just five IO lines:

    CS0 - chip select for device 0
    CS1 - chip select for device 1
    CS2 - chip select for device 2
    Clock - clock to all chips
    SIO - serial IO to all chips

    Use SHIFTOUT and SHIFTIN to communicate with the devices.

    ▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
    Jon Williams
    Applications Engineer, Parallax
    Dallas Office
  • Tracy AllenTracy Allen Posts: 6,664
    edited 2004-08-13 15:21
    Scott Edwards still has the documentation for the DCPB online for download at
    www.seetron.com/pdf/dcpb_mnl.pdf
    It used multiple 25LC640 for a data logger.

    Also see the Parallax app-mod
    www.parallax.com/dl/docs/prod/appkit/8kSerialEeprom.pdf

    ▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
    Tracy Allen
    www.emesystems.com
  • Velvet LeopardVelvet Leopard Posts: 47
    edited 2004-08-13 22:29
    Hewwo, all.· I just wanted to know if the Xicor X25640 8kB EEPROM was campatible with my 25LC640 EEPROM.· I mean connection wise.· Can I simply substitute my EEPROMs in place of the Xicor one in the PDF from above?· Also, I wanted to test if I did things correctly by putting some data in each chip and then reading it back and displaying it on the debug terminal.· I have five chips, but will just use three since it will be redundant to add the other two if the connections are the same as the others.· I want to place my full name in the chips, First, Middle, Last.· How would I code this and then place them and retrieve them in the three EEPROMs?· Thanks for your help.

    Post Edited (Velvet Leopard) : 8/13/2004 10:46:20 PM GMT
  • Velvet LeopardVelvet Leopard Posts: 47
    edited 2004-08-14 00:25
    Disregard my question on the compatibilities of the two chips I found out they have identicle pinouts.· The other questions still stand though.· =^.^=
  • Velvet LeopardVelvet Leopard Posts: 47
    edited 2004-08-14 01:48
    Okee.· I have wired up two 25LC640 EEPROMs on my Homework Board.· I believe all wiring is correct.· I am lost as to how to code the things.· Please don't laugh.· I am better with putting things together than programming them.· Specifically, I want to place the word "Velvet" in chip 0 and "Leopard" in chip 1.· Then I want the program to read back the words from chip 0 then chip 1 and place the data in the debug window.
Sign In or Register to comment.