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    Please do not post a support request without first reading and following the advice in https://retropie.org.uk/forum/topic/3/read-this-first

    What am i doing wrong with my hd44780 16x2 lcd?

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    hd44780 16x2 lc
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    • cyperghostC
      cyperghost
      last edited by cyperghost

      Can you measure voltage on HV? That has to be 5,0V
      Then connect HV also to VCC on your I2C LCD - with 5,0V

      The connection HV and LV on level shifter is only for internal comparism 3,3V and 5V it is not intended as supply. The LCD must glow if the there is 5,0V...
      The Pi got annothe 5V pin... Pin2! Use that for LCD connect!

      EDIT: Sorry Pin 2 is already used... Can you expand it? Or what about Pin 4? You need 5V for the LCD!

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      • BozB
        Boz
        last edited by Boz

        Ok so I just add a wire from pin 4 on pi(dac) to vcc on i2c and leave the rest?

        I thought the idea was to not directly connect 5v power to the i2c backpack ?

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        • cyperghostC
          cyperghost
          last edited by cyperghost

          Yes
          But I'm not sure if the device can be detected. I2C is multibus so it should work.... but we will see. Maybe I2C adresses from your devices are the same. Just connect and report!
          Your have a seconds Pi.... maybe you can get it on this to work?

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          • BozB
            Boz
            last edited by Boz

            Will connecting pin4 directly to the lcd not damage the pi?
            I thought that was the reason I got the level shifter?

            If I was to solder a 2nd wire to HV header on the level shifter and connect that wire to VCC on the i2c would that solve the problem?

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            • cyperghostC
              cyperghost
              last edited by cyperghost

              No...
              There are voltage output pins!
              2x 5V and 2x 3,3V ... The 5V can output the same amount as the power supply so very robust
              the 3,3V can only output 40 or 60mA that's enough vor LEDs or a few IC.

              The rest are "sender" and/or "receiver" Pins.
              They sending with 3,3V and if they are receiving data the voltage level should also 3,3V
              5,0V is much to high... So the level shifter reduces or highers only the "sender" and "receiver" parts. It has nothing to do with the power supply. Got it?

              You can also try to split the Pin1 to work with level shifter and LCD.

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              • BozB
                Boz
                last edited by

                Thanks now I understand,
                I'll solder a wire onto the HV pin then and see what happens :)

                LV (red) to pin1 on dac
                HV (orange) to pin2 on dac / VCC on i2c
                GND (grey) to pin6 on dac
                GND (grey) to GND on i2c
                LV1 (blue) to pin3 on dac
                LV2 (yellow) to pin 5 on dac
                HV1 (blue) to SDA on i2c
                HV2 (yellow) to SDL on i2c

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                • cyperghostC
                  cyperghost
                  last edited by

                  Yes ... Seems right now

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                  • BozB
                    Boz
                    last edited by

                    1 Reply Last reply Reply Quote 1
                    • BozB
                      Boz
                      last edited by

                      Success!!! Thank you so much!!

                      1 Reply Last reply Reply Quote 1
                      • cyperghostC
                        cyperghost
                        last edited by cyperghost

                        @Boz Nice video - thanks for posting!
                        Worked the python driver I posted?
                        Your setup is interesting? What's the name of the frontend? It does not look like Emulation Station?

                        BozB 1 Reply Last reply Reply Quote 0
                        • BozB
                          Boz @cyperghost
                          last edited by Boz

                          @cyperghost The front end is an Attractmode skin called Hyperpie, it can be quite laggy even with an overclock. I also have the comic book theme on emulationstation installed, I'm able to switch between them in the menu...I'm undecided which one to use at the minute.
                          The lcd software/driver is a package of python scripts that includes I2C_LCD_driver.py, retropie_clcd.py and some others.
                          The package is called RetroPie-Clcd and can be found here:

                          https://github.com/zzeromin/RetroPie-Clcd

                          Some parts of retropie_clcd.py were unfinished such as the system names which I finished off, then I just changed the intro messages and it was done. (one slight problem still remains but i'll come back to that at a later date).
                          I'm just going through the missing artwork at the min so I can finish the image and make a backup,
                          Thanks for all your help and patience :)

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