SPI mode for module HD44780

Posted on
  • Hi guys,

    I am planning to interface my Pico with a 20x4 character OLED display OLED-020N004B from Vishay (info here: https://www.vishay.com/displays/list/pro­duct-37706/). It seems to behave like a HD44780-like display: the built-in controller is a "OLED-0010", doc here: http://docs-europe.electrocomponents.com­/webdocs/1401/0900766b814011cc.pdf

    This controller has the ability to interract with 6800, 8080 and SPI interface. SPI seems to be mapped on DB7(MOSI), DB6(MISO), DB5(SCK) and E(CS).
    I had a look at the HD44780 module (http://www.espruino.com/modules/HD44780.­js); it does not seem to support SPI mode right now.

    Does anyone have any idea of how I could add a .connectSPI method on this module?

  • Hi!

    You should be able to do:

    var HD44780 = require("HD44780").HD44780;
    connectSPI = function(spi, cs) {
      return new HD44780(function(x, c) {
        // ...

    That'll work even without touching the module - but if you get something working it'd be great if you could contribute your code so I can stick it in the main one :)

  • @Gordon, did you just change the module per this occasion? ...because when I look at it I see:

    ...straight out of the 'Header' of modules/HD44780.js:


    If you have one of the LCDs with an I2C backpack, just use:

    I2C1.setup({scl:B6, sda:B7});
    var lcd = require("HD44780").connectI2C(I2C1);
    lcd.print("Hello World!");

    You can specify device address following way:

    require("HD44780").connectI2C(I2C1, 0x3F);

    Otherwise try:

    var lcd = require("HD44780").connect(A4,A5,A0,A1,A­2,A3);
    lcd.print("Hello World!");


    The implementation is:

    exports.connectI2C = function(/*=I2C*/i2c, _addr) {
      return new HD44780(function(x, c) {
        var a = (x&0xF0) |8| ((c===undefined)?1:0);
        var b = ((x<<4)&0xF0) |8| ((c===undefined)?1:0);
        i2c.writeTo(_addr || 0x27, [a,a,a|4,a|4,a,a,b,b,b|4,b|4,b,b]);

    So there is a plain .connect(... and a .connectI2C(....

  • ... and right at the bottom there's exports.HD44780 = HD44780; - so you can access the HD44780 class directly :) I think this came up before when someone was looking at driving the display via a different kind of IO expander, and it got added there.

  • Post a reply
    • Bold
    • Italics
    • Link
    • Image
    • List
    • Quote
    • code
    • Preview

SPI mode for module HD44780

Posted by Avatar for Jean-Philippe_Rey @Jean-Philippe_Rey