How to read & write to a 25aa1024 (1 Mbit SPI Bus Serial EEPROM) via 16F88

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  1. - 17th April 2010, 06:34 #1
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    Sorry, read the data sheet wrong. Nevermind
    Last edited by ScaleRobotics; - 17th April 2010 at 06:50.
  2. - 17th April 2010, 19:45 #2
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    Whoops it dawned on me what I am doing by changing that Bit. I guess that my novice understanding of this made me stumble upon the fact that I am now writing and reading from a different Chip Select, but seeing how I only have the one chip I dont understand how its reading/writing chip 01 when it should be chip 00.

    So I guess where I was calling it the A2 bit its actually the A0 bit that I was changing.
  3. - 17th April 2010, 20:05 #3
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    How do you have pins A0 and A1 connected?

    I have not had a chance to work on this today yet so I do not have any new news.
    Dave
    Always wear safety glasses while programming.
  4. - 17th April 2010, 20:11 #4
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    Quote Originally Posted by mackrackit View Post
    How do you have pins A0 and A1 connected?

    I have not had a chance to work on this today yet so I do not have any new news.

    Tied to ground.
  5. - 17th April 2010, 22:48 #5
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    mackrackit, You can't use Shiftout and Shiftin for an I2C bus driven part. That is why you had no luck using it with a 24FC1025... It requires the pullup resistor for communicating the ACK signal back to the processor. Shiftout keeps the pin in an active state wghich ever it is... I recently posted code for talking to 24LC1025's here on the forum... Why not just use it for a starting point... I don't remember which thread it was in reply to but I believe it had to do with I2C....

    Dave Purola,
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  6. - 17th April 2010, 23:42 #6
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    Dave,

    I've searched through all the posts on the 24LC1025 and didn't find any code you posted but I found code that is basically the same as what I have tried already. If you can find the thread you were thinking of that would be great.

    The only thing I have not tried is changing is my pullups from 4.7k to 2k and trying to write to it 1 page at a time but if I cant byte-write to begin with I'm sure the page write will not work either. I will try changing the Pullups tonight and see what happens.
  7. - 18th April 2010, 00:51 #7
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    I got the idea for shifting here.
    http://www.rentron.com/PicBasic/i2c_communication.htm

    Reading back over my code and data sheet I see some things are backwards. Maybe ...

    Never did find that code posting. Found lots of others for different parts.
    Dave
    Always wear safety glasses while programming.
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