Looking for a good tutorial on using LM3914 with LED bar and an Arduino

Other Hardware LEDs and Multiplexing
1

I have an Arduino UNO and a 10 segment LED light bar and i want to find a way to use it without using up all my pins. Is there a simple way to use only a few pins to use the bar? i plan on using a potentiometer to make the bar go up and down.

2

Look at a 74HC595

3

Or two.

4

Is the bar 10 discrete LEDs or something else?

5
6

We need an SPI.transfer( ) tutorial in place of shiftOut( ).

7

We need an SPI.transfer( ) tutorial in place of shiftOut( ).

I thought you had that just about ready to release?

8

It depends on what sort of display you need.
If it is an increasing bar then take a LM3915, and feed it with filtered PWM, therefore you just do it with one pin.

9

Grumpy_Mike:
It depends on what sort of display you need.
If it is an increasing bar then take a LM3915, and feed it with filtered PWM, therefore you just do it with one pin.

Yes, I just want to increase the bar as you turn the Pot, Is there a Tutorial for that?

10

jardane:
I have an Arduino UNO and a 10 segment LED light bar and i want to find a way to use it without using up all my pins. Is there a simple way to use only a few pins to use the bar? i plan on using a potentiometer to make the bar go up and down.

Why don't you just use a chip that does that...

eg. LM3914

11

Not nearly as much fun that way tho ...

12

I just ordered two LM3914 chips, this is perfect for what I need! In the end it will only take up one pin!

13

I am trying to learn how to use the LM3914 chip with a 10 segment LED bar and an Arduino Duo. I want to use a potentiometer to turn up and down the bar.

I can't find a good tutorial on how the LM3914 chip works and how to wire it to an Arduino.

14

One topic, one discussion please.
Read the datasheet - you need to drive an analog level into pin 5.
Use a PWM output, add an RC filter to filter it into a smoother output, the chip can take it from there.

15

I can't find a good tutorial on how the LM3914 chip works

Tutorials exist for people who can't or won't read the data sheet. There is not a tutorial on everything. However in this case it is simple.
Understand what PWM is:-
http://www.thebox.myzen.co.uk/Tutorial/PWM.html
The use google to search for images of :-
LM3914
and you get lots of schematics.

16

jardane:
I am trying to learn how to use the LM3914 chip with a 10 segment LED bar and an Arduino Duo. I want to use a potentiometer to turn up and down the bar.

I can't find a good tutorial on how the LM3914 chip works and how to wire it to an Arduino.

Make up your mind, operated by a potentiometer or from an Arduino?

Pelle

17

Or just use the one in the datasheet.

18

i tried to make a new post, but it tacked it onto this one instead.

I am still learning so data sheets are a little over my head.

19

No, I combined them. Hence ,the earlier comment.
The datasheet has a drawing of how you connect the part, your arduino PWM output & arduino Gnd will connect to pin 5.

20

jardane:
I am still learning so data sheets are a little over my head.

OK
Here's a way (attached.)

IMG_1721.bmp (370 KB)