7-segment LCD for DIY - Page 1
Forum section: electronics / beginners

author: aluck
author_rank: Regular Contributor
timestamp: February 18, 2012, 05:21:09 am
content: I want to put a small 4 or 6 digit 7-segment LCD in my next project. HD44780-based boards are way too bulky.There are several examples of using PCF8566 + LCD-S301C31, but the last one is hard to get.Could someone recommend a good compact 7-seg?

author: amspire
author_rank: Super Contributor
timestamp: February 18, 2012, 05:48:25 am
content: What range of sizes do you want?Do you want a smaller HD44780-type 4 bit parallel interface or a serial interface? Backlighting?You can start off at the Newhaven site:http://www.newhavendisplay.com/

author: aluck
author_rank: Regular Contributor
timestamp: February 18, 2012, 06:46:01 am
content: Quote from: amspire on February 18, 2012, 05:48:25 amI want a small one, like 10x50 mm, optional backlighting, any interface.As for Newhaven - they have all varieties of character LCDs, and I need 7-segment one.

author: amspire
author_rank: Super Contributor
timestamp: February 18, 2012, 07:49:32 am
content: Just went to mouser.com, and they have plenty including the 3 digit LCD-301C31 that you mentioned. You can get 4, 5 and 6 digits.The smallest and cheapest was the LCD-S401M14TF at about $1.74 - 20mm x 10mm outside dimensions. Characters are 4.42mm high.http://www.lumex.com/specs/LCD-S401M14TF.pdfI know Digikey and many of the other distributors have similar displays.Richard

author: amyk
author_rank: Super Contributor
timestamp: February 18, 2012, 11:03:59 am
content: That might be because that model is discontinued. I don't see any other reference to it on the Lumex site.Note that these are cheap because they're just the glass and crystal. No controller. You need a suitable AC driving signal generator to use them.

author: aluck
author_rank: Regular Contributor
timestamp: February 18, 2012, 12:45:58 pm
content: Quote from: amyk on February 18, 2012, 11:03:59 amYes, I understand. My reason for using 7-segs is not the price, but aesthetics.

author: TerminalJack505
author_rank: Super Contributor
timestamp: February 18, 2012, 12:52:23 pm
content: I've had good luck with Lumex's static LCDs. I haven't used the multiplexed displays, however.If you have enough I/O pins on your MCU you can skip the PCF8566 and drive a static (non-multiplexed) LCD directly from the MCU. Some MCUs have LCD drivers as well, which I'm sure you're well aware of.

author: aluck
author_rank: Regular Contributor
timestamp: February 18, 2012, 01:12:19 pm
content: Quote from: TerminalJack505 on February 18, 2012, 12:52:23 pmI am going to use low-end 8-bit ATMega's, so there's never enough I/O, and no built-in LCD.Anyway, external LCD driver seems much more reliable - no way I'm going to risk blowing up the whole LCD with DC voltage if my MCU would hang up.

author: TerminalJack505
author_rank: Super Contributor
timestamp: February 18, 2012, 01:53:22 pm
content: Quote from: aluck on February 18, 2012, 01:12:19 pmYep. I hear ya.What I've always wanted is something in-between a static LCD and an HD44780-based module. Basically just a static module with a chip stuck to the back of it. The chip would be nothing more than a glorified shift register and display driver. Have one bit for each of the segments (on or off) and some simple interface to shift-in new values.This would reduce the number of pins to a half-dozen or so and you wouldn't have a clunky software interface or a clunky physical package.

author: electrode
author_rank: Regular Contributor
timestamp: February 19, 2012, 01:00:57 am
content: To be honest, the cheapest way to do that would probably just be to grab a PIC or AVR with just enough pins, and program it to multiplex the (eg.) 4 digits continuously with whatever it's told to do via SPI/I2C. Getting that on an SMD package neatly on the back of the 7-segs would be nice, then just a 4 pin header with Vcc, GND, SCL, SDA.

author: amyk
author_rank: Super Contributor
timestamp: February 19, 2012, 09:12:00 am
content: Quote from: TerminalJack505 on February 18, 2012, 01:53:22 pmThe higher-resolution graphic LCDs have this interface, but I don't think any 7-segment ones do.

author: sonicj
author_rank: Frequent Contributor
timestamp: February 19, 2012, 08:20:32 pm
content: maxim has some chips that give you serial/parallel to triplexed alphanumeric/7seg.linkpersonally, i always liked the "bubble led" displays. a single dl2416, dl1414, etc would give you your 4 alphanumeric digits with decoder & character generator onboard.image from theVintage Technology Association

author: azrobbo
author_rank: Newbie
timestamp: February 25, 2012, 11:09:27 pm
content: Sparkfun sells 4-digit 7-segment displays with a serial/SPI interface. They can be found here:http://www.sparkfun.com/products/9765

author: Psi
author_rank: Super Contributor
timestamp: February 26, 2012, 01:37:58 am
content: If you want something cheap, these are quite good valuehttp://www.jameco.com/webapp/wcs/stores/servlet/Product_10001_10001_2005497_-1You can even use them on their side with a 5x3/4/5 font.But you still need a driver/mcu to drive the led matrix.

author: aluck
author_rank: Regular Contributor
timestamp: February 26, 2012, 09:33:40 am
content: Quote from: azrobbo on February 25, 2012, 11:09:27 pmThose are:LEDs, not LCDexpensivecontain a whole Atmega 328 inside (wonder why they wouldn't just put a simple Intel Pentium just to drive 4 digits)

author: Bored@Work
author_rank: Super Contributor
timestamp: February 26, 2012, 02:26:21 pm
content: Quote from: aluck on February 26, 2012, 09:33:40 amPentiums are so old school. Apparently each 7 segment display needs a seven + 1 core i7. The eight's core is to drive the decimal point.

author: sacherjj
author_rank: Frequent Contributor
timestamp: February 26, 2012, 03:36:55 pm
content: All Electronics is a surplus parts seller. Although they usually have enough of a data sheet or link to a proper one that you can figure something out. They don't seem to have anything on this guy. Although it is 1" high and you don't define compact.http://www.allelectronics.com/make-a-store/item/LCD-200/2-DIGIT-LCD/1.htmlDigikey also has quite a few 7 seg LCD displays. less that .5" high.

author: sonicj
author_rank: Frequent Contributor
timestamp: February 26, 2012, 10:10:18 pm
content: are you designing a sweet new pager?-sj

author: aluck
author_rank: Regular Contributor
timestamp: February 27, 2012, 12:01:26 pm
content: Quote from: sonicj on February 26, 2012, 10:10:18 pmIt's going to be an AD9851 based function generator.

author: sonicj
author_rank: Frequent Contributor
timestamp: February 27, 2012, 08:53:00 pm
content: nice.i know its not lcd, but these have a classy look imo. driver is built in.alpha numeric

author: T4P
author_rank: Super Contributor
timestamp: February 27, 2012, 08:55:03 pm
content: Quote from: sonicj on February 27, 2012, 08:53:00 pmWow , "SINGAPORE" Haven't seen anything made here for a long time

author: aluck
author_rank: Regular Contributor
timestamp: February 27, 2012, 11:06:27 pm
content: nice indeed.V - means Vintage

author: nessatse
author_rank: Regular Contributor
timestamp: February 28, 2012, 12:12:55 pm
content: Quote from: Dave.S on February 28, 2012, 10:07:58 amwhoosh!

author: aluck
author_rank: Regular Contributor
timestamp: February 28, 2012, 01:48:25 pm
content: I am going to borrow a "SARCASM" sign from The Big Bang Theory.

author: sacherjj
author_rank: Frequent Contributor
timestamp: February 28, 2012, 02:19:47 pm
content: Quote from: aluck on February 28, 2012, 01:48:25 pmOn another forum I frequent, we have created a convention of using purple text for sarcasm, because there was a collision of smart asses and those with no sense of humor.