radioshack 7-segment red led 0.3" digital display help please...

i just bought my son a couple of radioshack 7-segment red led 0.3" digital displays.. (since we are awaiting different ones to come in that we bought on ebay.. the pins are different). i haven't found any real tutorials on these, and i have come across other people having the same issue..

the back of the package says:

  1. anode F
  2. anode G
  3. no pin
  4. common cathode
  5. no pin
  6. anode E
  7. anode D
  8. anode C
  9. anode RHDP
  10. no pin
  11. no pin
  12. common cathode
  13. anode B
  14. anode A

have a look here for back of package..

can anybody please tell us exactly how to hook this up... we have an arduino 2560...

thank you..

What is wrong with this:-
http://www.hacktronics.com/Tutorials/arduino-and-7-segment-led.html

How are you planning to use it - multiplex by driving 1 anode High at a time while the common cathodes are connected to each other with a series resistor to Gnd?
Or by driving all anodes at once each with their own series resistor, with the 2 common cathodes connected to Gnd?

we just want to make it work lol..

seriously tho,we want to click a button and make it count up and then start over i'm not sure about what you are asking, it's our first digit led

based on the exact one, we just would like to wire it up, but have not seen any tuts for this specific 7-segment led

basically we just don't get this thing, no matter how we wire it up...

@grumpymike
we want to know how to hook this one up, pins are lined up differently (we also don't see a pin 14... 13 is the highest)... so that loses us right there.

13 is the highest

But you posted pin 14's connection in the original post.

Sure the pin numbers are different but the circuit will be the same, just change it to the pin numbers you have.

ok, keep in mind we are new to arduino and all this.. so we don't understand as much as you guys..

does each pin require a resistor? if so, which?

i thought this thing was going to be fun, so i bought the arduino for my son and a bunch of misc parts on ebay.. so we don't have everything we need, but slowly getting it and getting the parts we need.

so please be patient... i don't want every post i make to turn into an argument with people on here...

if there is a schematic for the exact one we have, we would like to see it... we never wired up a digit led before. we just don't get it atm

Tutorial Your Display
Segment A pin 7 Segment A pin 14
Segment B pin 6 Segment B pin 13
Segment C pin 4 Segment C pin 8
Segment D pin 2 Segment D pin 7
Segment E pin 1 Segment E pin 6
Segment F pin 9 Segment F pin 1
Segment G pin 10 Segment G pin 2
Cathode Pins 3 & 8 Cathode Pins 12 & 4

does each pin require a resistor

Yes. Try 220R but it is not too critical.

ty, i will try that..

ok, that didn't work.. also, according to the top part of the coding - there is no mention of pin 10

void setup() {
pinMode(2, OUTPUT);
pinMode(3, OUTPUT);
pinMode(4, OUTPUT);
pinMode(5, OUTPUT);
pinMode(6, OUTPUT);
pinMode(7, OUTPUT);
pinMode(8, OUTPUT);
pinMode(9, OUTPUT);
digitalWrite(9, 0); // start with the "dot" off
}

tutorial my display

Segment A pin 7 Segment A pin 14
Segment B pin 6 Segment B pin 13
Segment C pin 4 Segment C pin 8
Segment D pin 2 Segment D pin 7
Segment E pin 1 Segment E pin 6
Segment F pin 9 Segment F pin 1
Segment G pin 10 Segment G pin 2
Cathode Pins 3 & 8 Cathode Pins 12 & 4

here is how i have it hooked up...

#14 is connected to pin 7
#13 is connected to pin 6
#8 is connected to pin 4
#7 is connected to pin 2
#6 is connected to pin 1
#1 is connected to pin 9
#2 is connected to pin 10

12 & 4 are connected to ground on bread board

#9 is not connected at all

resistors are connected to ground on breadboard to their digit led pin wire.. using 5x 220 and 4x 680 because i don't have anymore 220's

here's what it's doing: - YouTube

ground is connected to arduino mega 2560 from the breadboard

according to the top part of the coding - there is no mention of pin 10

That is because the arduino pin 10 is not involved.

I think you are getting mixed up with what is a pin on your display and what is a pin on the arduino board.

here is how i have it hooked up...

#14 is connected to pin 7
#13 is connected to pin 6

What does the # denote? If it is an arduino pin then

resistors are connected to ground on breadboard to their digit led pin wire

The resistors should be connected to the arduino pin and the other end of the resistor should be connected to the appropriate segment anode of the display.

denotes the number on the back of digit led package as stated in the main post..

Sorry I can't make anything out from that video.

#6 is connected to pin 1

So if that is pin 6 on the display connected to pin 1 of the arduino it is not correct.
Arduino Pin your display
2 resistor 14
3 resistor 13
4 resistor 8
5 resistor 7
6 resistor 6
7 resistor 2
8 resistor 1
ground 12 & 4

Your display is numbered so that pin 1 is the top left hand corner looking at the front of the display.

ok, that works better.. but some numbers are in complete or have an extra led on.. ex for 3 it shows A,B,G,C,D & E

and for 5... it shows A, F G and C but not showing D

2 doesn't even show, 0 is missing C

for experimental purposes, i put #9 with #7 on the breadboard.. the dot lights up when it's supposed to (i guess)... but that's neither here or there..

complete numbers i do get are: 1, 4, 5, 6,7, 8, 9 (5 had a loose resistor)

OK it is debug time.

First off check that each segment is controllable independently.

Write a sketch that just puts one segment on and check it is right. Repeat for all 7 segments. Maybe you could write a sketch to to that all in one go but I am assuming you can't.

int totest = 2;
void setup(){
pinMode(totest, OUTPUT);
digitalWrite(totest, HIGH);
}
void loop() { }

Change the number assigned to totest one at a time until you have covered all the segment pins.
If that works then it is a software error you have made, if it doesn't then you have a wiring error.

for 1 shows: nothing
for 2 shows: A
for 3 shows: B
for 4 shows: C
for 5 shows: E,D
for 6 shows: E,D
for 7 shows: G
for 8 shows: F
for 9 shows: nothing
for 0 shows: nothing

my connections are:
arduino pin 2 = led 14

the only numbers messing up are: 0, 2, & 3
arduino pin 3 = led 13
arduino pin 4 = led 8
arduino pin 5 = led 7
arduino pin 6 = led 6
arduino pin 7 = led 2
arduino pin 8 = led 1

led 12 & 4 are ground

the only numbers messing up are: 0, 2 and 3

for 1 shows: nothing
for 9 shows: nothing
for 0 shows: nothing

No surprise as pins 0, 1 an 9 on the arduino are / should not be connected to anything.

for 5 shows: E,D
for 6 shows: E,D

That is not correct. This implies that pins 5 and 6 are somehow connected together. Check your wiring on this very carefully.

well, 9 is for the dot if i wanted to use it, which i don't - i have no need for it... i checked my connections, they seem fine.. will check another led.. i bought 2 of them.. lol

yep, confirmed... used a second one without resistors this time... same no change and everything is hooked up as you stated:

Arduino Pin your display
2 resistor 14
3 resistor 13
4 resistor 8
5 resistor 7
6 resistor 6
7 resistor 2
8 resistor 1
ground 12 & 4

0,2 and 3 are the only ones messing up...

ran a quick sketch of my own..

void setup() {
pinMode(2, OUTPUT);
pinMode(3, OUTPUT);
pinMode(4, OUTPUT);
pinMode(5, OUTPUT);
pinMode(6, OUTPUT);
pinMode(7, OUTPUT);
pinMode(8, OUTPUT);
// pinMode(9, OUTPUT);//dot
// digitalWrite(9, 1); // start with the "dot" off
}

void loop() {
delay(1000);
// write '3'
digitalWrite(2, 1);
digitalWrite(3, 1);
digitalWrite(4, 1);
digitalWrite(5, 1);
digitalWrite(6, 0);
digitalWrite(7, 1);
digitalWrite(8, 0);
delay(1000);

}

to make the 3 show... pin 7 had to be changed from 0 to 1 and 8 had to be changed from 1 to 0...

same with making the 2 show properly..

void setup() {
pinMode(2, OUTPUT);
pinMode(3, OUTPUT);
pinMode(4, OUTPUT);
pinMode(5, OUTPUT);
pinMode(6, OUTPUT);
pinMode(7, OUTPUT);
pinMode(8, OUTPUT);
// pinMode(9, OUTPUT);//dot
// digitalWrite(9, 1); // start with the "dot" off
}

void loop() {
delay(1000);
// write '3'
digitalWrite(2, 1);
digitalWrite(3, 1);
digitalWrite(4, 0);
digitalWrite(5, 1);
digitalWrite(6, 1);
digitalWrite(7, 1);
digitalWrite(8, 0);
delay(1000);

}

problem solved… switch arduino pins 7 & 8… all works fine now! woot!

ty mike!

problem solved

:slight_smile: :slight_smile: :slight_smile: