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Driving the LCD - share your experience

Anthocyanina

Hi! So, I've been working on the software for this challenge and have reached the point where i need to figure out the LCD. The datasheet has a character map and and the addresses for the position of each character. I don't have much experience with driving LCDs so I'm struggling with where to start. Have any of you figured out the LCD yet? 

I found a couple threads on the arduino forum that talk about this display, with people saying you could use the HD44780 libraries, or similar to drive it. I'll be trying that with an arduino board first, but still would like to hear about your experience with this display so far. 

Thank you!

  • in reply to javagoza

    That looks great! Thanks for sharing!

  • in reply to Anthocyanina

    This is the wiring that I am using for testing with the Raspberry Pi CM4 module.

    image

    If you leave unconnected SA0 and SA1 the I2C address is 0x3F

    image

    image

  • in reply to jc2048

    image

      A quick adaptation of your script. Works! Thanks for sharing!

    from smbus2 import SMBus

LCD_CLEARDISPLAY = 0x01
LCD_FUNCTIONSET_4LINE_5x8DOTS_BITMODE = 0x38
LCD_DISPLAYCONTROL_ON = 0x0C
LCD_ENTRYMODESET_LEFT = 0x06
LCD_1LINE = 0x80
LCD_2LINE = 0xC0
LCD_3LINE = 0x94
LCD_4LINE = 0xD4


# initialise the LCD panels
# and write the static first line
bus = SMBus(1)

firstLineString = "#### ELEMENT14 #####"

displayBuffer = [0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0]
for i in range (0, 20):
  displayBuffer[i] = ord(firstLineString[i])

bus.write_i2c_block_data(0x3C , 0x00, [LCD_FUNCTIONSET_4LINE_5x8DOTS_BITMODE])
time.sleep(0.015)
bus.write_i2c_block_data(0x3C , 0x00, [LCD_DISPLAYCONTROL_ON])
time.sleep(0.001)
bus.write_i2c_block_data(0x3C , 0x00, [LCD_CLEARDISPLAY])
time.sleep(0.001)
bus.write_i2c_block_data(0x3C , 0x00, [LCD_ENTRYMODESET_LEFT])
time.sleep(0.01)
bus.write_i2c_block_data(0x3C , 0x00, [LCD_1LINE])
bus.write_i2c_block_data(0x3C , 0x40, displayBuffer)
time.sleep(0.01)
bus.write_i2c_block_data(0x3C , 0x00, [LCD_2LINE])
bus.write_i2c_block_data(0x3C , 0x40, displayBuffer)
time.sleep(0.01)
bus.write_i2c_block_data(0x3C , 0x00, [LCD_3LINE])
bus.write_i2c_block_data(0x3C , 0x40, displayBuffer)
time.sleep(0.01)
bus.write_i2c_block_data(0x3C , 0x00, [LCD_4LINE])
bus.write_i2c_block_data(0x3C , 0x40, displayBuffer)

  • I just created a first version of a Raspberry Pi python library for the RW1063 LCD controller of the MIDAS Display.
    I will update as I add new functionality to the library. You are free to use it however you want, without any guarantee, I haven't tested it thoroughly yet.

    https://github.com/javagoza/lcdrw1063

  • in reply to javagoza

    oh wow, that's amazing! thank you for sharing. i think i might end up using it in this challenge. i tried writing a library myself, but i can barely handle loops and ifs in software! :P

  • in reply to Anthocyanina

    You and anyone else are welcome to use that library.

    In any case, after having studied the data sheet and the controller manual well, I think that any library that works for the HD44780 could work for you.

    Aspects to configure:

    • I2C communication. It should allow the address to be configured to any of these values: 0x3C, 0x3D, 0x3E or 0x3F
    • Data length 8 bits, this is important, since many libraries that work with parallel communication only implement 4-bit communications
    • Configuration of the 2-line display, although the display has 4 lines, it is configured as two 2-line displays working in parallel with two LCD drivers.
    • Only write mode is allowed for I2C, instruction write, and memory write operations can be used. It is not possible to use read operations, the display only asserts with ACK, it does not send data via I2C.
    • The DDRAM memory addresses of the four display lines are 7 bits: 0x00, 0x40, 0x14, 0x54
    • The CGRAM memory addresses for custom characters are 6 bits, from 0x00 to 0x56, each 5x8 bit character you need to send 8 bytes to configure it.

    Some of the aspects that I want to improve in my implementation are:

    • Add digital port for controlling the Chip Select (CS) state from the library.
    • Add a digital port to turn the LCD backlight on/off.
    • Add configuration of number of columns and rows.
    • Property for setting cursor at specific row and column position. cursor_pos = (0, 5)
    • Encapsulate private methods.

    Finally, I must remind myself that the purpose of this challenge is to test the Hammond enclosure, that this is an accessory aspect and although I am having a great time, the box is calling me in my dreams.

  • in reply to javagoza

    actual dreams? i want to experiment with makeshift magnetic connectors to interface with the outside world. i tried with a piece of polycarbonate, and it went so bad i ended up actually having a bit of a nightmare about the actual enclosure breaking and falling apart when i tried the magnetic connector in an actual dream, hahahaha

  • in reply to Anthocyanina

    I have ordered a capacitive sensor, the cheapest I have found, I want to do tests to see if it is capable of detecting my fingers behind the lid. Good idea about the magnetic sensor, it could be put on one of the sides.

  • in reply to Anthocyanina

    Some time ago I built a magnetic quadrature encoder with magnetic reed switches.

    This encoder can be hidden on the internal lateral sides of the enclosure.

    VenTTracker #07 - Adjusting the window sensor

  • in reply to javagoza

    oh, i meant a magnetic connector, like these

     image

    my idea was to have ferromagnetic contacts, melting through the plastic to make a waterproof seal, and then use a cable attached to tiny magnets to get signals into and out of the box, more than the 2 we can get out of it with the included connector. but my experiments with a polycarbonate piece i had were not successful at getting a waterpoof seal or even a good melting! I'll be showing that in a blog :P