problem with I2CWRITE command

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  1. - 14th October 2010, 14:32 #1
    hatzukitzuki's Avatar
    hatzukitzuki
    hatzukitzuki is offline Junior Member
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    Bert (and all),
    the problem around I2C is more complicated as I have thought earlier. First, to understand both examples (working and non-wirking) above, it is necessary to study ByVac I2C LCD datasheet. The command $03 writes directly to LCDcontrollers, while command $20 recall routines of the MCU on he I2C ByVac LCD controller. There are of course more commands.

    I did tests with all ByVac commands and changed step by step the "control" variable at I2CWRITE bit by bit. The "control" variable has no influence to I2CWRITE. Still I don't understand it's meaning.

    The I2C analyzer shows bus conflicts / errors. On another place of this forums, in one thread, I have read user's problem with I2CWRITE in case of master/slave devices.

    On the other hand, if I use assembler and write the communication from LAB-X1 to ByVac I2C interface to LCD in assembler, I can use without problems all ByVac interface's commands ... $03, $20, $25... etc., while PBP has problems.
  2. - 14th October 2010, 15:00 #2
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    cncmachineguy
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    Is the above your full test program? Have you told PBP osc speed? I will go try to find a datasheet for byvac lcd.
    -Bert

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  3. - 14th October 2010, 15:11 #3
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    First off, when you said you looked at the online manual I figured you did not have the printed manual meaning ....
    For that I apologize.

    Th control is specific to the part being used. I have not used the part you are using so I will need to look at the data sheet when I get back to the shop.

    Control does have read/write bits set but normally PBP will changes those for you at compile time.

    In th meantime maybe this will help, maybe a work around if PBP does not work well with your part.
    http://www.picbasic.co.uk/forum/cont...-EEPROM-Part-1
    Dave
    Always wear safety glasses while programming.
  4. - 14th October 2010, 22:35 #4
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    Assuming this is the data sheet
    http://www.i2c.byvac.com/downloads/B...0DataSheet.pdf

    On the other hand, if I use assembler and write the communication from LAB-X1 to ByVac I2C interface to LCD in assembler, I can use without problems all ByVac interface's commands ... $03, $20, $25... etc., while PBP has problems.
    From what I see on the above data sheet that would be correct. The display is not setup to have more than one on a bus so it does not use a control bit.

    Looks like you will have to use SHIFTOUT. But if you have an ASM routine working just put that into the PBP code.
    Dave
    Always wear safety glasses while programming.
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