Which LCD module should I buy for the Prop?

Brian L

I'm new to the prop and was wanting to play with one of the LCD displays, and prefer a cheap one for now. I see Parallax has a couple of 2x16 serial ones for 30 bucks, a 2x16 parallel one for 30, and a 4x20 one for about 36 bucks. I figured some of you guys probably have experience with most or all of these and could guide me into one that works well with the Prop and is already well supported with some nice objects in the library. Any thoughts on what I should get?

Thanks,
Brian

deSilva

The typical 2x16 uptp 4x20 or 2x40 LCD displays are generally based on the 44780 driver chip. They all have (nearly) the same 16 pins connectors. I shall link one of the many threads discussing that matter
http://forums.parallax.com/showthread.php?p=682817

They are available in the millions throughout the world, for as low as $8. I would recommend Marcel's driver but the others work as well...

Post Edited (deSilva) : 12/31/2007 4:01:07 AM GMT

Drone

Hi Brian,

Welcome! IMHO you can't go wrong with the Parallax 4X20 backlit serial LCD, Item code 27979, on sale right now for $35.95 USD. It is only $6 USD more than the 2X20 backlit serial LCD and I think you'll find the extra two lines are most welcome when using the display for debugging. I recommend you use the "debuglcd" program from the Propeller Object Exchange with your LCD. Here's the link to debuglcd:

obex.parallax.com/objects/40/

There are two minor things I don't like about the Parallax 4X20 LCD:

1. The backlight seems to be LEDs driven by DC. So when the backlight is on, it draws a decent amount of current. I wish Parallax would have allowed for the backlight to be driven by a pulse-width waveform, thereby possibly even allowing user brightness control. As it is now, you only have on/off control of the backlight.

2. The maximum serial rate is 19.2 kbps. I'd like to see it handle up to 57.6 or 115.2 kbps.

It seems the controller on the back of the 4X20 backlit serial LCD is a Parallax SX chip, so Parallax seems to have control of these issues. But as I mentioned above, these are minor issues - at $36 the 4X20 display is a square deal.

Good Luck, David

Brian L

Glad to hear it David, because the 4x20 is the one I just ordered a while ago. I'll download that object too.

Thanks for the reply.

Sleazy - G

yeh the 16x4 char lcd with sx chip piggyback is pretty sweet.· Mines been acting up tho, i think I might have fried the sx chip.··I plug things in wrong alot. When mine worked good it makes a·nice 3 pin deal with the sx, and like alot more without.· Im going to try to surgery·the sx chip off and either run it parallel, or put another sx on there,·ive got a few im not using.·

Fred Hawkins

Brian,
I like allelectronics for cheap lcd's -- http://www.allelectronics.com/

Sometimes their support threads are quite good. Take a look at their $18.50 256x128 lcd for instance.

Oldbitcollector (Jeff)

I bought my 20x4 LCD module from this vendor and then a LCD module from uController.com

$11.00 for the LCD, and $12.00 for the adapter, works great here.

OBC

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SrJuanCarlos

Hello everybody, I just got a propeller education kit that I have been messing around with for a week or so. Thanks for all the work you guys have done documenting this MCU; I really enjoy browsing through the forums, and over time, I know I will be posting a lot of questions.

I wanted to point anybody interested to www.goldmine-elec-products.com, where they have several 16x2 backlit LCD displays for $3.95 ($2.75 each if you buy 100 of them), www.goldmine-elec-products.com/prodinfo.asp?number=G16562 and www.goldmine-elec-products.com/prodinfo.asp?number=G16081, plus some other random displays. They advertise some odd drivers built in with them, but I did some research and they should both be pin compatible with the standard HD44780 driver that is included with the $29.99 Parallax one, with the addition of two pins for the back light. I haven't tried either of these yet, but I'm going to make an order here soon. I'll update this once I have some results.

John

deSilva

I have used at least 6 different brands of 44780 compatible displays without any problems. Differences are:
Where A and K pins for the baklight is allocated: those can be the first or the last pins
Voltage for the contrast can vary.
There are different addresses for the third and fourth line, but I also discused that in the thread I gave the link to above. However these are not deviations! You just have to keep in mind that a 4x16 is a different beast than a 4x20 display.

Mike Young

For a nice, powerful, easy-to-implement character LCD I've become partial to the Matrix Orbital LK404-25.

It has a 40x4 character display format, includes some GPIO pins, and also includes a 5x5 button keypad decoder. It uses serial, I2C, or 1-wire interfaces and works over a fairly large temperature range. Its extremely fast when used with I2C. Dislikes? Its relatively costly and I feel the backlight should be a tad brighter.

Note that the I2C interface is intended for use with 5V bus; in the LK404-25 designs I've done I've been using an I2C level translator chip (NXP semiconductor P82B96) to do the level translation. It may work with the prop using some 1k series resistors but I haven't tested this.

If there is interest I'll clean up my .spin code I2C driver for the LK404-25 and post it. Note that I haven't played with the keypad or GPIO yet but I like having those options available....

V/R
Mike

Leon

The Powertip LCD modules I have will work at 3.3V according to the data sheet. They will need a negative bias for the contrast pin at 3.3V, however, which isn't needed at 5V. It should be easy to generate it with a simple diode pump circuit driven from a counter.

Leon

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deSilva

Leon said...
... a simple diode pump circuit driven from a counter.

Yes, that works fine. I even drive the "pump" from a Propeller pin Or is this just what you wanted to say?

Leon

Yes, that's what I meant.

Leon

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liljoentx

Hey Fred Hawkins,

If you want some really good deals on LCD screens, check out EarthLCDs.

They have a 2.7" color one from Sony for $59.00:

http://store.earthlcd.com/Support/ezLCD-Technical-Info?search=Sony+ACX705AKM-7

Were desigend for use in a PDA...they only have 114,000 in stock, so you might want to get your order in quickly!

(I think I saw this one listed somewhere else, though, for like $17.50!)

Lil'Joe

deSilva

Bargain prices I am accustomed to are:
4 Euro for 2x16 or 2x20 text displays
20 Euro for 128x64 graphics displays (mono colored, low power)
30 Euro for 5 to 7" QVGA RGB screens, generally needing 12 V power supply, ans some special sync adaptation.