i think ive broken something, HELLLLLLLP!. (think its my lcd display)

Discussion in 'Embedded Systems and Microcontrollers' started by ninjaman, Sep 9, 2014.

  1. ninjaman

    Thread Starter Member

    May 18, 2013
    306
    1
    hello

    I have an arduino pro mini 5v 16Mhz, el cheapo from ebay, none official cheap Chinese rip off. the blink example worked.
    I have an lcd 1602 and bought a backpack that allows it to work serial so only four pins. vcc gnd sdl sda. these pins are matched on the mini, I uploaded the example sketch which didn't specify pin attachments so I have taken for granted that they are attached to I^2C in the sketch, somewhere in the background(not visible).

    a little red light appears on the backpack so there is a voltage going in but no lcd display. I measured voltage across pins and there is 3.4 volts on all four pins. this makes me think I have fried it.
    anyone know of any tests I could perform? not including the "hit it with a hammer test"
    thanks
    simon

    I did a little bit of testing and the voltage across vcc and gnd is 3.4 volts. so I thought it was 5 volts because that's what it said when I bought it. bloody cheap ebay scamming little F*&^%er's
    but if there are any other thoughts on this a I think the lcd should still work with 3volts
     
  2. MrChips

    Moderator

    Oct 2, 2009
    12,453
    3,371
    Unplug the display from the Arduino. Does the Arduino supply 5V or 3.3V?
     
  3. ninjaman

    Thread Starter Member

    May 18, 2013
    306
    1
    there is a switch on the programmer that I got separately. it can provide 3.3 or 5 volts. I switched to 5 volts and got about 4.89 volts. I adjusted the pot on the back of the lcd display and managed to get a single line display without the back light.
    I read some example sketches and they have pin outs but im not sure how they are connected up. I didn't really understand them.
    I don't know of any way to test the serial backpack, I could test the display as I can still attach some wires to the pins.


    I tried connecting the backlight just to check it and it works ok. though I cant connect the rest as the pins are not long enough
     
    Last edited: Sep 9, 2014
  4. MrChips

    Moderator

    Oct 2, 2009
    12,453
    3,371
    So let's review.
    You set the Arduino to output 5V.
    Now you see one row of black solid rectangles on the LCD. That is a good sign. This indicates that the LCD is powered up but not yet initialized.

    Now you have to find or write code that correctly interfaces with the LCD.
    Which pins from the Arduino are you using?
    If possible show photos of the LCD and its connector.
     
  5. ninjaman

    Thread Starter Member

    May 18, 2013
    306
    1
    im using a serial backpack, which means that I only have fours wires from the LCD to the Arduino. power, ground, sdl and sda. these go to the Arduino, 5 v, ground, sdl and sda. the backpack connects to the pins on the LCD with an indication for pin1 and pin16. I just soldered it on.
    im having problems finding the right library as they seem to require another library to make them work. I read about a newsoftserial.h library which allows you to choose another serial port as the pro mini only has one serial port. the newsoftserial.h allows you to create another using software. using this and the serialLCD library. but the sketch doesn't show any connections for the LCD just and address 0x27 and 16, 2 for columns and rows. no pin information. I have found some pin information from a different site using the same serialLCD library, but it doesnt mention any order. im not sure how to find the pin out as this is a Chinese copy.


    WOOOO, I GOT IT WORKING!!!
    USED THIS I^2C SCANNER PROGRAM TO FIND THE ADDRESS ON THE ARDUINO OF THE I^2C, THEN CHANGED THE SKETCH, THEN ADJUSTED THE CONTRAST AND NOW ITS WORKING!!!
     
    Last edited: Sep 11, 2014
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