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BUF12840: BUF12840 datasheet description

ONISHI Yasushi
Prodigy 50 points
Part Number: BUF12840

Dear Sir;

I read the BUF12840 datahseet, and then I have 2 question.

Q1) Page 4  PIN DESCRIPTION about EA1, EA0

      It says EEPROM select bit*. EA* should be tied to logic'0' if autoread is not used.

      I think TCON can read and write BUF12840 DAC register even if EA* is '1' Page8 Figure10.

     I would like to know why it say EA* should be '0'  if  command setting (no autoread )is used ?

Q2)P10 Table4 EEPROM Configuration

    In case of  EA0 = 0 and EA1=1, BANK0 start adrs is 361, it says 2k eeprom is acceptable.

   But 2k eeprom is 256x8, so adrs 361 is out of memory size.

   Why 2k EEPROM is okay?

Regards;

   

  • 0
    TI__Expert 4940 points
    Hello,

    I'll answer your questions tomorrow.

    Thank you,
    Costin
  • 0 in reply to Costin Cazana
    TI__Expert 4940 points
    Hello,

    Q1) Enable pin is used to select between master and slave mode.
    A) En=High: After POR BUF12840 will autoread the EEPROM since it is the master of the bus. After reading the EEPROM BUF12840 enter the slave mode and TCON is the master
    B) En=Low: BUF1280 will go directly into slave mode and TCON is the master. Changing En status will have no affect after POR

    Q2) I'll get back to you next week

    Regards,
    Costin
  • 0 in reply to Costin Cazana
    Prodigy 50 points

    Dear Costin-san;

    Thank you for replay.

    Q1) ---> I understand your comments. However, there is still a question.

                  Does EA(1:0) need to be "00" at the time of the slave mode ?

                  Because T-CON can set data to BUF12840's DAC register. I think EA(1:0) is no relation to DAC register at the time of slave mode.  

     Regards; 

  • 0 in reply to ONISHI Yasushi
    TI__Expert 4940 points
    Hello,

    That's correct. Enable Pin sets BUF12840 in slave mode, EA are active only during master mode

    Regards,
    Costin
  • 0 in reply to Costin Cazana
    Prodigy 50 points

    Hi, Costin-san;

    Thank you for support.

    As for EEPROM size, I read the buf12840 datasheet  again.

    It says that P10 Table4

    " (2) When EA0 = 0 and EA1 = 1, it is required that the types of EEPROM that supports Page/Block address definition with chip select pins
    (for example, A0 is part of the Word Address).".

    What is necessary is just to change 2k EEPROM address map.

    For example, I set 2k EEPROM's pin A2 A1 A0 = "001".

     Regards;