Command structure for NHD-0220D3Z-FL-GBW-V3



  • kayasaman

    Here are some images of the project with the displays.

    If anyone knows of a way to throw commands at the displays without needing to compile a full C program it would be great. Currently sending Hex codes to the displays don't seem to work so if somehow I could just clear the screen to start with then produce some characters then text on the display it would be great.


  • Ted M.
    NHD Staff

    Please confirm the RS-232 signal driving the display is 5V TTL .

    Best Regards,

  • kayasaman

    The display is being driven at 5V. The documentation says RS232. My level shifter is converting the uart port on the Pine64 which is a 3.3V TTL signal to 5V RS232.

    Perhaps there is confusion here as RS232 is not the same as TTL though the documentation for the display clearly says RS232.... therefor if the display should be driven at 5V TTL then it is not RS232.

    I can try with a TTL signal of 5V but I will need to find a converter to amplify the 3.3V signal from the pin and bring it up to 5V.

  • kayasaman

    What I am using at present is this:

    It is taking the 3.3V uart signal from the Pine64 and translating it to full swing -5V - +5V RS232.

    If it is TTL that I need to send to the display then I will need to convert the RS232 signal to 5V TTL which will then range between 0V - +5V.

    One attachment I have included shows the "level shifter" on the right hand side (small square) and the other illustrates the differences between TTL and RS232 levels taken from the link above.

  • kayasaman

    I managed to figure this one out!  

    It is indeed a TTL signal that the display needs and *not* RS232!

    Perhaps it would be a good idea to change the documentation as that threw me off totally  

    Throwing a few commands at the display and getting results now   

    Although the voltage is 3.3V TTL at present for this quick test.

    What actually is needed for me so that I don't strain the display is a level shifter and not converter; another words not a board which takes the input TTL signal and then goes full swing RS232.

    I think this is what I'm looking for:

    which should take the 3.3V TTL input from the Pine and amplify it to 5V TTL output for the display. I'm just confirming it currently with the Artekit guys though there are many different brands available - SparkFun being another.

    Now I can at least start working a driver for Lcdproc so that I will be able to get my GPS's NMEA sentances, NTP information and other useful output on the display.


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