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  1. #41
    Join Date
    Mar 2008
    Posts
    41

    Default Re: Interfacing with Arduino I2C LCD

    Quote Originally Posted by richard View Post
    interpreted as [( 7bit_addr, EN, RW, RS, D4, D5, D6, D7, Backlight, POLARITY) ]

    the PCF8574 datasheet indicates the 7bit addr range is 0x20--0x27

    0x3f is not valid afaik.


    default with a0:2 open = 7bit_addr of 0x27 , pbp addr would be $4e
    I see on the data sheet for the PCF8574 you are right I used the Arduino i2c address finder to get the address. I have tried it using the 4E address and get nothing however with the 7E I do get some response from the display. I am still trying to understand the Initialization string and how to use it if you can offer guidance it would be appreciated. This is a little beyond my current ability but I will continue to try to learn and get this project going.

    Thank You!

  2. #42
    Join Date
    May 2013
    Location
    australia
    Posts
    1,109

    Default Re: Interfacing with Arduino I2C LCD

    did it work with the Arduino sketch ?
    if so what was the init command [I assume a0:2 are open]
    LiquidCrystal_I2C lcd(0x27, 2, 1, 0, 4, 5, 6, 7, 3, POSITIVE) or LiquidCrystal_I2C lcd(0x27, 4, 5, 6, 0, 1, 2, 3, 7, NEGATIVE);
    afaik there is at least two types there may be others.
    if the addr is not between 0x20 and 0x27 then its a going to be different animal and the include files may need modification

    would not hurt to trace out the cct and see what bits are wired to rs,e,rd/wr etc
    This is more entertaining than Free to Air TV

  3. #43
    Join Date
    Mar 2008
    Posts
    41

    Default Re: Interfacing with Arduino I2C LCD

    Quote Originally Posted by richard View Post
    did it work with the Arduino sketch ?
    if so what was the init command [I assume a0:2 are open]
    LiquidCrystal_I2C lcd(0x27, 2, 1, 0, 4, 5, 6, 7, 3, POSITIVE) or LiquidCrystal_I2C lcd(0x27, 4, 5, 6, 0, 1, 2, 3, 7, NEGATIVE);
    afaik there is at least two types there may be others.
    if the addr is not between 0x20 and 0x27 then its a going to be different animal and the include files may need modification

    would not hurt to trace out the cct and see what bits are wired to rs,e,rd/wr etc

    This is the init command from my working Arduino sketch "LiquidCrystal_I2C lcd(0x3F, 2, 1, 0, 4, 5, 6, 7, 3, POSITIVE)" all three jumpers are open A0:2.

    Thanks!

  4. #44
    Join Date
    May 2013
    Location
    australia
    Posts
    1,109

    Default Re: Interfacing with Arduino I2C LCD

    This is the init command from my working Arduino sketch "LiquidCrystal_I2C lcd(0x3F, 2, 1, 0, 4, 5, 6, 7, 3, POSITIVE)" all three jumpers are open A0:2.
    ok must be PCF8574A [addr range 0x38-0x3f]

    so $7e is sounding good for an address , one of those includes should work .

    another thought
    you did not specify osc speed you may need
    DEFINE I2C_SLOW 1
    Last edited by richard; - 27th February 2017 at 05:42.
    This is more entertaining than Free to Air TV

  5. #45
    Join Date
    Mar 2003
    Location
    Commerce Michigan USA
    Posts
    995

    Default Re: Interfacing with Arduino I2C LCD

    Make sure of the IC Type. A PCF8574 (non A) has an upper nibble of 4 for the address and the PCF5874A version has an upper nibble of 7 for the address. NXP did this to allow upto 16 devices on the I2C bus.
    Dave Purola,
    N8NTA
    EN82fn

  6. #46
    Join Date
    Mar 2008
    Posts
    41

    Default Re: Interfacing with Arduino I2C LCD

    PCF8574AT is the number on my IC.

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