LCD/LED Displays for beginers - Page 1
Forum section: electronics / beginners

author: cowboy303
author_rank: Regular Contributor
timestamp: March 15, 2012, 05:16:37 pm
content: Hi guys.I'm trying to put to gether a Power supply kind of like Dave's (A little simpler) And was working on a display I plan on using a Atmega328p-pu and program it with the Arduino uno rev3 (like Dave). I would like a display for Volts and Amps I was thinking on using a 2x__ character display but don't know witch one to get.I'd like something easy to work with but is not restricting for me later.If any body knows of one that would be grate.And if any body can show me what to look out for when buying one that would also be nice.Thank you every one if you have any questions please ask.

author: 8086
author_rank: Super Contributor
timestamp: March 15, 2012, 05:25:09 pm
content: Look for HD44780 compatible displays, if you only want voltage and current then 2x8 would probably be enough. Or a 2x16 if you want more flexibility.

author: mariush
author_rank: Super Contributor
timestamp: March 15, 2012, 05:50:04 pm
content: The easiest ones to to work with are the ones that accept parallel input or i2c (but i2c may not be available in some controllers or you may reach the device limit with other components)I'm currently working with a Midas made LCD sold by Farnell, a 4 x 16 one:http://uk.farnell.com/midas/mc41605b6w-sptly/lcd-4x16-stn-ylw-green-b-l-5mm/dp/2063248but there's plenty of 2x16 or 1x16 there which are also parallel input.Here's the full page with all the lcds:http://uk.farnell.com/displays-lcd_alphanumericAnd here's some examples of 2x16 screens that would work:http://uk.farnell.com/midas/mc21605a6w-fptlw/lcd-2x16-fstn-white-led-b-l-5v/dp/2063170?in_merch=New%20Productshttp://uk.farnell.com/midas/mc21605a6wd-bnmlw/lcd-2x16-neg-stn-white-led-b-l/dp/2063158?in_merch=New%20Productshttp://uk.farnell.com/midas/mc21605b6w-fptlw/lcd-2x16-fstn-white-led-b-l-5v/dp/2063169http://uk.farnell.com/midas/mc21605b6wd-sptly/lcd-2x16-stn-ylw-green-b-l-5mm/dp/2063240The last two are with the pins arranged in an 2x8 set on the left of the screen. This is better if you want to use cheap existing cables to connect it to your pcb (where you solder a 2x8 0.1" pin header) but the lcds in the first links with all the pins in a row are better suited for breadboards as you can solder a row of header pins and then just plug the lcd in the breadboard like in the videos below.The one I bought has a Sunplus controller, which is basically a clone of HD44780 chip, so it works just the same.You need a minimum of 7 pins to talk to it, 3 for control commands and 4 pins to send half a byte, two times. If you want, you can use the full 8 pins of data to send a byte at a time.But basically, with the 7 wires it's very convenient to tie it directly to the controller or if you want to save some pins you can use a .5$ serial to parallel chip which will receive 8 bits in a row from your controller through 2-3 pins and send 7 bits out of those 8 to each lcd pin.Here's a very good tutorial about using such LCD with the controller :

author: cowboy303
author_rank: Regular Contributor
timestamp: March 15, 2012, 11:32:41 pm
content: Thanks guysThose are good videos really informative.I think I'll get that one off Deal Extreme. But does any body know how long it will take for me to receive it.Thanks again.

author: caroper
author_rank: Regular Contributor
timestamp: March 15, 2012, 11:48:46 pm
content: I gotthis onefrom AdaFruit to experiment with, it took about 3 weeks to get to Africa, should be much quicker for you in America. Not sure how it compares price wise, to getting it from China, but $10 was far cheaper than any source I found locally (I spread shipping over several other items) and the support is great.p.s. I also wanted it it play with Dave inspired PSU projects and find that 2x16 is just enough to handle a 2 Chanel PSU.for the difference in price I think I would go with 20x4 next time.

author: vk6hdx
author_rank: Regular Contributor
timestamp: March 16, 2012, 05:57:25 am
content: +1 for the HD44780 display. Using the LiquidCrystal Library in the Arduino IDE makes this easy. You'll need 6 pins to drive it though.http://arduino.cc/en/Tutorial/LiquidCrystalCheers,Troy

author: cowboy303
author_rank: Regular Contributor
timestamp: March 16, 2012, 06:50:08 am
content: QuoteAdafruit it is. I was looking what else they had to combine shipping and they also got a Atmega328p with a Arduino bootladderhttp://www.adafruit.com/products/123thought that was pretty cool.

author: metalphreak
author_rank: Frequent Contributor
timestamp: March 16, 2012, 06:52:02 am
content: Yeah definitely go for a HD44780 display. They are very easy to use and there are plenty of examples/libraries you can use.You can also get them in quite a variety of coloursPerhaps a different colour for Volts and Amps?http://www.goodluckbuy.com/character-lcd-module-lcm-jhd-16x2-jhd659-16x2-10-color-aviliable.htmlAdafruit sell ones with RGB backlights so you can make basically any colour, and you'll probably receive them faster, but at a higher cost.

author: Mechatrommer
author_rank: Super Contributor
timestamp: March 16, 2012, 08:24:59 am
content: dave sales the 2x16 at aud2.5 each x10 unit here...http://www.eevblog.com/shop/if you want save for combine shipping, you may get as well this, one or two...

author: Mechatrommer
author_rank: Super Contributor
timestamp: March 16, 2012, 01:38:03 pm
content: Quote from: Dave.S on March 16, 2012, 09:51:48 amduh! he already in my "suppliers list"

author: cowboy303
author_rank: Regular Contributor
timestamp: March 16, 2012, 05:28:07 pm
content: Thank you guys I think I'll get the 4x20 LCD but I just want to make sure of some stuff.I still only need 6 I/O on the arduino.and it said that the whole screen is 2x7cm that's means that the digits are 5mm is that right or did I read it wrong.Thanks Again.P.S. It looks like Dave's sold out on all his stuff in his store(just saying).

author: sacherjj
author_rank: Frequent Contributor
timestamp: March 16, 2012, 05:29:52 pm
content: Quote from: cowboy303 on March 16, 2012, 05:28:07 pmThat is the way I read it and WAY too small for a power supply display, in my opinion.

author: T4P
author_rank: Super Contributor
timestamp: March 16, 2012, 05:30:47 pm
content: I have a solution to our LCD problems :http://www.dealextreme.com/p/16-x-2-character-lcd-display-module-with-blue-backlight-121356

author: cowboy303
author_rank: Regular Contributor
timestamp: March 16, 2012, 05:40:06 pm
content: Quote from: Dave.S on March 16, 2012, 05:30:47 pmFirst Wow that was fast.I like the looks of it. But It does not say it is a HD44780 display. But it does have 16 connectors which I think is a tell tale sign that it is.Thank You

author: T4P
author_rank: Super Contributor
timestamp: March 16, 2012, 06:02:05 pm
content: It's a HD44780-driven display

author: cowboy303
author_rank: Regular Contributor
timestamp: March 16, 2012, 08:42:43 pm
content: Quote from: Dave.S on March 16, 2012, 06:02:05 pmThank you very much!I will plan on buying it tomorrow that way I can see if any body can see any problems with it.Thank you All especially Dave.S for always being there to help.

author: metalphreak
author_rank: Frequent Contributor
timestamp: March 17, 2012, 08:07:18 am
content: The 4x20 displays have the same (physical) size characters as the 2x16, 2x20 etc. So 2x7cm is definitely wrong.The 4x20 displays are a bit funny as well, because of the way the controller works, the lines aren't in order. It still acts like a "2 line 40 character" display but is arranged like this:Line1:Chars1-20Line2:Chars1-20Line1:Chars21-40Line2:Chars21-40So if you just bang in data with the auto-character increment turned on, everything goes from Line 1 onto Line 3, to Line 2 and finally Line 4

author: poodyp
author_rank: Regular Contributor
timestamp: March 17, 2012, 06:16:40 pm
content: Just think of it the same way you would having two 595s connected. The HD44780 only supports 2*20 max, so to get 4*20 there are two of them tied together.

author: sonicj
author_rank: Frequent Contributor
timestamp: March 18, 2012, 12:09:10 am
content: Quote from: sacherjj on March 16, 2012, 05:29:52 pmtakes a bit more code...

author: mariush
author_rank: Super Contributor
timestamp: March 18, 2012, 02:09:18 am
content: The LCD controllers have a number of characters hard coded and a bunch of positions where you can "upload" characters.For example, the LCD I linked in one of my previous post has 48 places where you can define custom characters ... each one is basically 5 bytes (5x8 pixels)With a bit of programming to manage the 48 slots for characters, you can basically use every one to treat the 16x2display as a 80x16 dot matrix screen as in the picture above...

author: sonicj
author_rank: Frequent Contributor
timestamp: March 18, 2012, 05:33:45 am
content: surplus Nokia 3110, 5110, etc lcds are cheap and easy.Nokia 5110 with breakoutMaxim MAX7219 & MAX7221 are easy to drive if you're trying to light 7 or 14 segment led displays. its a expensive chip retail, but can be had on the cheap via china.anyone know of a source for affordable HD44780 OLEDs?-sj

author: metalphreak
author_rank: Frequent Contributor
timestamp: March 19, 2012, 09:46:40 am
content: Quote from: poodyp on March 17, 2012, 06:16:40 pmA single HD44780 can actually address 80 characters, as 2 lines of 40 chars. It is the 4x40 char lcds that need two controllers and an expansion chip.It's just odd that they split the first 40 bytes of the character address ram across lines 1 and 3, instead of just 1 and 2. There must be a technical reason for it, but it makes no sense from a programming point of view.This probably explains what I mean better:QuoteQuote