USB Interface For Parallel LCDs

Pontus Frönder has put together a really simple USB interface for any LCD that uses the HD44780 controller. He used a USB chip from FTDI that creates a virtual COM port on the host computer. This is connected to an Atmel ATtiny2313 which controls the LCD. The AVR has two PWM outputs that are used to control the backlight and contrast. If the current draw of the backlight is low enough it can be driven directly from the USB and since it looks like a standard serial display you can talk to it using programs like LCD Smartie.

12 thoughts on “USB Interface For Parallel LCDs

  1. uggg, if the driver to that usb-to-serial chip is as bad as the one for my nokia phone data cable (gprs internet) NOBODY is gonna want to install it on a windows box… osx version works great tho, go figure.

  2. i’ve got a Nokia 3590 that i’d like to play around with, but i can’t figure out how to tell which controller it uses for the LCD – i’ve searched every set of numbers on the circuit. Any ideas?

  3. FTDI makes pretty decent serial-usb chips. Lots of hobbiests use them, especially when their microcontrollers don’t natively support USB (some of the newer PIC’s do).

    jared, it seems as if the 3590 and the 3510 are interchangable models where the lcd is concerned. Here is a pinout to the 3510, as well as a datasheet:
    Epson S1D15G14 LCD Chip…

    You probably won’t find any code, especially to drive that color LCD, so good luck and have fun hacking away. If you can’t work your way through the pdf, check out

    they have code and pictures, which kind of takes the fun out of it.

  4. #2 do you know if your cable uses the Prolific chip or the CP2101 from Silicon Labs? I have the CP2101, using it under osx… i wonder which is better as I’m considering buying a few to convert them to regular usb2serial adaptors. Branded ones, like Keyspan’s, are really expensive. This would be a nice alternative if you don’t wanna deal with the ftdi chip, which I believe only comes in surface mount. Then it’s simply a matter of getting a Serial2Parallel uart such as the 6402. I know it’s old and not that easy to get, but it works good and it’s simple as hell. Check here for a few example circuits :

    I’m using a similar circuit to drive a 2×40 VFD and a 4×4 matrix keypad. Using RS232 is perfect for me as the circuit is located about 100~150ft (worth of cat5e) away from the host machine.

  5. FTDI has a newer chip out the FT245R, as well as the FT232R, Both require almost no external components, just a few decoupling caps, the FT245R is a usb to 8 bit parrallel fifo, very easy to use, all of the FTDI chips have 2 driver options, the VCP (Virtual Com Port) or a DLL based driver that can be used in custom programs.

    Also to get away from the surface mount both of these 2 chips come as 24-pin dip modules that can be used on a breadboard or perf board.

    These 2 new chips are natively capable of High speed USB as well if you need it, no external components necessary to add that functionality.

    I just wrote an entry on using the new 232 chip, but plan on using the fifo chip soon in a design.


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