LTP2657AA 5X7 LED display
Jonathan
Posts: 1,023
Hi all,
On a whim I bought a couple LTP2657AA 5X7 LED displays. These have 28 pins, in two rows of 14, and are bi-colored, red and green. I have been playing around with them trying to figure out the pinout.
I can make each LED light up (I think, haven't actually lit them all) but some have more than one way to connect them. Meaning I can use two different pin combinations to make one LED glow with the same color. I am slowly making a map of the device, but if anyone could point me to a data sheet, I'd be grateful. I had no luck looking for one myself.
Another question, what is the best device to drive this thing? I have some 74HC595's that I could use to experiment with, as long as I use high value resistors to limit current. It'll be dim, but I can play around.
I'm hoping to figure these things out so that I can make a project for high school students to build a scrolling sign or graphics display. Although I shudder to think what they will spell/draw with it ;-0. I think I could get a bunch of these cheap, if I can get 'em to work. Once I get it to work I'll whip up a VB interface for it to make for easy programming. These may be a good project for me to try out the SX chips I have.
If by any dim chance someone has done a project with these devices, and code or help would be great! Using either the BS2XX or the SX chips in SXBasic.
Thanks!
Jonathan
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www.madlabs.info - Home of the Hydrogen Fuel Cell Robot
On a whim I bought a couple LTP2657AA 5X7 LED displays. These have 28 pins, in two rows of 14, and are bi-colored, red and green. I have been playing around with them trying to figure out the pinout.
I can make each LED light up (I think, haven't actually lit them all) but some have more than one way to connect them. Meaning I can use two different pin combinations to make one LED glow with the same color. I am slowly making a map of the device, but if anyone could point me to a data sheet, I'd be grateful. I had no luck looking for one myself.
Another question, what is the best device to drive this thing? I have some 74HC595's that I could use to experiment with, as long as I use high value resistors to limit current. It'll be dim, but I can play around.
I'm hoping to figure these things out so that I can make a project for high school students to build a scrolling sign or graphics display. Although I shudder to think what they will spell/draw with it ;-0. I think I could get a bunch of these cheap, if I can get 'em to work. Once I get it to work I'll whip up a VB interface for it to make for easy programming. These may be a good project for me to try out the SX chips I have.
If by any dim chance someone has done a project with these devices, and code or help would be great! Using either the BS2XX or the SX chips in SXBasic.
Thanks!
Jonathan
▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
www.madlabs.info - Home of the Hydrogen Fuel Cell Robot
Comments
I can just tell, you've got too much time on your hands again :-)
The "LT" in the part number of this bi-color 5 x 7 Dot Matrix LED display would tend to indicate that it might be made by Liteon. Seeking that out, we end up at the Liteon web site in Taiwan:
···· http://www.liteon.com.tw/databook/default.htm
There we can drill down to "Dot Matrix LEDs" and then to "Multi-Colour". Sure enough, there is our LTP2657AA, and clicking on that nets us a datasheet, which I've hopefully attached.
The datasheet tells us that this is an "anode column and cathode row" device.·Now we switch gears and go seeking a 5 x 7 dot matrix LED driver chip for this type of device.
The Maxim 6952/6953 chips look like good choices:
···· http://www.maxim-ic.com/quick_view2.cfm/qv_pk/3379
It looks like that has a built-in text character set, and the whole 9 yards! After that, you're on your own my good man.
Regards,
Bruce Bates
Your right Bruce, I do have too much time on my hands! It's 3 weeks until I start teaching, and I have all my classes organized, so I thought I'd pound my head with these displays.
I am very jealous of your web searching abilities!! Guess I've always ridden the short bus on the internet ;-0
Thanks for all the help. I had only about half finished mapping the display, so the data sheet saved me a lot of time. I ordered a couple of samples of the MAX6952 and MAX6953. Looks like the only difference between the two is that the '53 is I2C compatible.
These displays will make a great high school student project if I can figure them out. The display chips are a little expensive, but I should be able to get the total parts cost in under $20, which is about the max for HS students to pay. Expect more questions once I get the chips!
Jonathan
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www.madlabs.info - Home of the Hydrogen Fuel Cell Robot