LED Display found in kit

Electrically Challenged · 2013-10-03 10:02

LFD5522-10/SP10-1

This was found in my kit, but is not listed in the book. It's your basic 7 digit - LED display, but 4 times. It has 12 connectors, but I have no drawings for how to hook it up. Do I need a special device for it and any suggestions on how to code it? Is there a quick link that will give me what I need?

Thanks in advance,

Ron

Jen J. · 2013-10-03 10:41

Is it this 7-segment LED? http://www.parallax.com/product/350-00027

Which kit do you have? BASIC Stamp Discovery Kit? BASIC Stamp Activity Kit?

Electrically Challenged · 2013-10-03 10:51

No. There are 4 of those in line.

See attached.

Ron

Mike Green · 2013-10-03 10:51

That part number is used in SparkFun's displays. These come in different colors and the proper voltage (or current limiting resistor value) depends on the color. They use 16 pins, not 12, so I'm not sure what you have. Here's a link to their red version. They have a link to the datasheet on that webpage. The datasheet has the pin-out. Other links give examples for the Arduino.

Electrically Challenged · 2013-10-03 10:53

Actually, I'm not sure which kit. I imagine the Basic Stamp Activity Kit. I've had it for awhile.

Ron

Electrically Challenged · 2013-10-03 10:56

Nope. Not it. Their display had three extra dot displays which I don't have.

Ron

Electrically Challenged · 2013-10-03 11:04

Well, that's alright if we don't know. I have a Cub Scout Pack meeting coming up and hoping to have something interesting to kickstart their brains... For some reason the regular 7 digit display isn't functioning right. It's either in the code or it's a laptop glitch which I haven't quite found the time to investigate, but time is running out. At first I thought it was the display and then discovered the display functioned fine. So, then I assumed it was a P15, but have recently discovered that to be functioning. It worked fine on the big computer, but recently got a laptop and it doesn't want to work completely. 90% of it works, but I can't find a thing wrong with the code (which doesn't mean a whole lot). So... more complicated than it ought to be.

I went to looking at this display thinking I might make something out of it.

Ron

Electrically Challenged · 2013-10-03 11:15

I found an electronic diagram via Google Images that led to your site. Looks like I need the Arduino Shield to do anything with it - assuming I understood everything there.

http://learn.parallax.com/4-digit-7-segment-led-display-arduino-demo

Ron

Duane Degn · 2013-10-03 11:20

Are you sure it's a Parallax kit?

8 of the pins will control the segments and 4 will control which digit is displayed.

The 4 pins to control the digit will either be a common anode for all segments within a digit or a common cathode for all segments of a digit.

You could figure out the pins yourself by using a DMM in diode mode or with 5V and something like a 560ohm resistor. By watching to see which segment lights up when power (with current limiting resistor) is applied, you can figure out which pin does what. It would probably help to look a datasheet for a similar display to see the way segments and digits are controlled.

Mike Green · 2013-10-03 11:34

The particular example you found was for the Arduino, but the same circuit could be used with a Basic Stamp. With changes in resistor values due to the use of 3.3V instead of 5V, it could be used with a Propeller as well. There are some examples of this in the Nuts and Volts Column archive for the Stamp on Parallax's website. You're providing very little information about what you have and what you want to use to make it work, so it's hard to offer advice.

Electrically Challenged · 2013-10-03 11:35

It's entirely possible it found its way into the kit. According to the previously mentioned Parallax link, I will need 4) 2n2222 NPN Transistors. Don't know if I have enough of those, but... It's starting to make sense. I'll have to look at the provided code from that page and see what it is going to do with the display.

Thanks guys,

Ron

Electrically Challenged · 2013-10-03 11:38

Yep, you are right. Sorry, don't come here very often. I think I have what I need. Your suggestion of dropping down to 3.3V is helpful. Thanks,

Ron

Duane Degn · 2013-10-03 11:39

Electrically Challenged wrote: »

Looks like I need the Arduino Shield to do anything with it

You don't need an Arduino Shield. They're LEDs. You can control them the same as other LEDs. You just also need to control the common cathode or common anode to select which digit you want to use. Since the common anode or common cathode may have the current of up to eight LEDs passing through it you'll want to use a transistor to control the common pin (anode of cathode) instead of connecting it directly to a Basic Stamp.

Chris Savage · 2013-10-03 12:18

I have never seen such a part in any of our kits. Since we do not stock it there is no way I can think of that it would have come from us with that part included. If you bought it from another vendor it may have found its way in there through some other means.

erco · 2013-10-03 14:11

@EC: Are you using the BS2 HW board (you mentioned the Activity kit earlier)? That has inline 220 ohm resistors on all the I/O lines, perfect for driving LEDs such as yours (no add'l resistors needed). Here's an 8-digit display (16 pins) running of a HW board.

Duane Degn · 2013-10-03 14:35

erco wrote: »

@EC: Are you using the BS2 HW board (you mentioned the Activity kit earlier)? That has inline 220 ohm resistors on all the I/O lines, perfect for driving LEDs such as yours (no add'l resistors needed). Here's an 8-digit display (16 pins) running of a HW board.

I think you ought to add that the display your using has the transistors for the digits built in. Won't Ron need transistors to turn on the individual digits? He can certainly use one digit by itself without a transistor which may be a good way to get started.

If large enough resistors (eight times the normal value) were used, the display could probably be driven without a transistor. The segments would be pretty dim though.

IMO, one of the first things to figure out about the display is to see if it's a common anode or common cathode.

I know I've mapped out the pins on an unknown display like these before. It's not too hard and kind of fun.

erco · 2013-10-04 11:10

Duane Degn wrote: »

I think you ought to add that the display your using has the transistors for the digits built in.

It's not too hard and kind of fun.

Yes and yes. Duane and I similarly find pleasure in things that many others find objectionable or a downright PITA. Speaking of which, Duane, just today I had a flash of inspiration for a most challenging project that that you, Martin_H and others would LOVE. Servos, steppers, camera, controller. Surely my next article for SERVO. Or is there a contest somewhere?

Steph Lindsay · 2013-10-04 11:44

For the record, Parallax briefly distributed a 4-character 7-segment LED display in promotional kits for the microMedic National Contest 2013. (See the winning inventions here!) That's why we have a demo using the display with the Arduino Shield; the kit came in Propeller BOE and Arduino Shield options. There are a few kits left in stock of each version:

microMedic Kit with Propeller Board of Education

microMedic Kit with Board of Education Shield (for Arduino)

Duane Degn · 2013-10-04 11:52

Steph Lindsay wrote: »

For the record, Parallax briefly distributed a 4-character 7-segment LED display in promotional kits for the microMedic National Contest 2013.

From the earlier link, I think it's safe to assume the display Ron has isn't the one from the Parallax kit.

Ron's display appears to have a single row of pins while the Parallax display has two rows.

@erco, You've got me curious but I have all projects but my CNC router on a back burner. Once I have the CNC up and running there will be great things (or at least mildly interesting things) to follow.

LED Display found in kit

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