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EEPROM Compatibility — Parallax Forums

EEPROM Compatibility

idbruceidbruce Posts: 6,197
edited 2011-07-09 21:44 in Propeller 1
Hello Everyone

Just a quick EEPROM question. Is the 16 Kbit (2 KByte) I2C Serial EEPROM (24LC16B) compatible with the prop chip and/or is it simply to small to hold any type of program?

Bruce

Comments

  • Mike GreenMike Green Posts: 23,101
    edited 2011-07-09 08:05
    You really need to practice reading datasheets. There's a description in the 24LC16B's datasheet of how address information is sent to the EEPROM. Look at the format. Compare that to the description and format shown in the same section of the 24LC256's datasheet. Do they match?

    The datasheets are readily available on the web.
  • idbruceidbruce Posts: 6,197
    edited 2011-07-09 08:31
    MIke

    I will admit that I never looked at the datasheets concerning this comparison, because I felt it would be way beyond my comprehension. Now after looking at both datasheets, I can see that they look very similar, but I am still uncertain, so the question still remains the same.

    Bruce
  • idbruceidbruce Posts: 6,197
    edited 2011-07-09 08:36
    P.S. I must have practiced reading over 50 datasheets in the last 2 days. Is it crime to seek help when one lacks expertise?
  • Mike GreenMike Green Posts: 23,101
    edited 2011-07-09 08:38
    If you'll look at the section of the datasheet I mentioned, you'll see that the 24LC16B requires one address byte to be sent to the EEPROM after the device select code. A 2K EEPROM needs 11 bits of address and that address byte supplies 8 of them leaving 3 bits more. The device select code provides those 3 bits as shown in the diagram in the datasheet. Contrast that to the 15 bits of address needed for the 32K byte of the 24LC256. The diagram in that datasheet shows two bytes of address which provides 16 bits of addressing, enough for 64K bytes of memory. The 24LC256, as shown in the datasheet, ignores the most significant bit. The 3 bits of address information in the device select code are used to select one of 8 different EEPROMs (if present). Now what do you think?

    In the attached datasheets, look at the 24LC256 datasheet, section 5, page 8 and the 24LC16B datasheet, pages 6-10,
    pdf
    pdf
    24LC256 Datasheet.pdf
    465K
    pdf
    pdf
    21703d.pdf
    333K
  • idbruceidbruce Posts: 6,197
    edited 2011-07-09 08:49
    Mike

    I did not ascertain my conclusion from reading the data sheets, but from the way that you state it, I would say they are incompatible.

    Bruce
  • idbruceidbruce Posts: 6,197
    edited 2011-07-09 08:49
    Mike

    Thank You

    Bruce
  • prof_brainoprof_braino Posts: 4,313
    edited 2011-07-09 10:29
    Hey Bruce and Mike

    Thanks for asking and answering this question. I also have an annoying pile of unused 24LC16B EEPROMs, I was thinking it might be fun if they could expand my Demoboard, but now it seems this would be a different project than I had in mind. You just saved me a week of scratching my head over these datasheets. :)

    What else can be done with these parts? Are they destined for Borg jewelry?
  • Duane DegnDuane Degn Posts: 10,588
    edited 2011-07-09 10:35
    I think you can still use the 2K EEPROMS with the Prop. You just can't boot from them.

    As long as you send the correct command and address (and use the smaller page size), the Prop should still be able to store and retrieve data from them.
  • JonnyMacJonnyMac Posts: 9,208
    edited 2011-07-09 10:41
    Remember to address the 2K EEPROM at %001 or higher to prevent conflict with the boot EEPROM as it uses the same device type nibble (%1010) in the slave ID byte.
  • IamretiredIamretired Posts: 56
    edited 2011-07-09 10:54
    Mike Green should pass on to a colleague questions that annoy him: it would benefit the questioner and it would benefit Parallax.
    John
  • GranzGranz Posts: 179
    edited 2011-07-09 21:36
    Iamretired wrote: »
    Mike Green should pass on to a colleague questions that annoy him: it would benefit the questioner and it would benefit Parallax.
    John

    Mike was probably not annoyed at these questions - he just sounded like he was. In my experience (small as it is) with Mike, he is first and foremost a teacher. As a teacher myself, I have found that the students learn far more by looking things up rather than just being given the answer. In his posts, Mike showed the location for obtaining the answer for anyone with a bit of experience with datasheets. When he realized that Bruce did not have that much experience, Mike just went into more detail and then attached the datasheets, so that Bruce would not have to hunt for them.

    Like I said, students learn more by looking it up, and to a teacher like Mike, everyone is a student.
  • idbruceidbruce Posts: 6,197
    edited 2011-07-09 21:44
    It's all good, Mike has helped me out on numerous occassions, and I am definitely thankful for all the help he has given me.

    Bruce
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