LCD Pinout and interfacing help - Page 1
Forum section: electronics / projects

author: joblessalex
author_rank: Contributor
timestamp: May 28, 2012, 08:59:34 pm
content: Hello everyone! I am new to the forums, and slightly new to electronics.I found thishttp://www.goldmine-elec-products.com/prodinfo.asp?number=G18246and made the mistake of buying it. I can't find information on the thing anywhere! I attemped to use an arduino to see if I could at least get some text on it, but I don't know which pins do what.Mods, if you want the images linked in, just ask or change it. They are large to show part numbers.If someone could give me any information on this, it would be greatly appreciated!

author: free_electron
author_rank: Super Contributor
timestamp: May 28, 2012, 09:26:08 pm
content: That's a controllerless display ... essentially a bunch of shiftregisters where you shove pixels in.. you need to refresh this thing continuously ... this display has no pixel memory of its own. not easy to control and pretty much useless unless you can get a hold of loose controllers like the tc6393 or sed12xx 's.

author: typeglob
author_rank: Contributor
timestamp: May 28, 2012, 09:29:08 pm
content: Threw the part number in google, which leads to:http://forum.lcdinfo.com/viewtopic.php?f=6&t=9011Clicked the ebay link on that page and found a zip with some more info.

author: joblessalex
author_rank: Contributor
timestamp: May 29, 2012, 03:09:41 am
content: Thanks for the help! Even if it was bad news, I guess there's not really much use for it either, unless displaying massive amounts of data is needed....

author: ColinB
author_rank: Contributor
timestamp: May 29, 2012, 07:38:56 pm
content: The LC79401 chips are 80-bit-wide segment driver chips (4 of the '401 chips equals 320 pixels wide); the LC79430 are 80-bit-wide common driver chips (3 of the '430 chips equals 240 pixels high).The row data is clocked on a 4-bit-wide serial bus. Look at the five traces entering IC4 that pass under the silk text "C12". These are the serial pixel data input for the row (CP, DI1, DI2, DI3, DI4) coming from the external interface connector. You can probably figure out how to drive this thing by using the LC79430 and LC79401 data sheets and tracing connections from the controller interface connector to the driver ICs on the board. It would be fun.You could probably drive this thing with decently powerful microcontroller. It seems like you clock the pixel data for a row into the four LC79401 segment driver chips, which accept 4-bit wide serial input. You basically clock in the display data one row at a time to refresh the display. Because it's not a single serial input stream, but a 4-bit-wide serial input, you won't be able to use a regular single SPI peripheral on a microcontroller. I would first just prototype it using GPIO directly, and you could do this on basically any decent microcontroller. (It will take 9600 bytes to store the pixel data for the frame, so you'll have the simplest time if you choose a microcontroller with 16KB+ of RAM (in the long run you could do on-the-fly pixel data generation so you don't have to buffer the entire display if you want to optimize cost). Once you have prototyped the LCD controller using GPIO directly, you should be able to use an external bus interface with DMA to automate sending pixel data to the LCD and allow your microcontroller to be mostly freed up to do other work while the DMA controller drives data to refresh the LCD. The high-density STM32 microcontrollers have a flexible static memory controller (FSMC) that can do this type of thing (other microcontrollers have similar features).Are you up for the challenge?