LED problem

My take is slightly different from that of suicidalacorn's... I think that with either 01 or 10 and therefore activating the R xor G LEDs, there's enough of a "short" across the AND gate for it to read both its inputs as 1's.

(Which is what suicidalacorn was saying, on second thoughts, now that I see his annotated pic....)

Do some measuring with your meter...

thanks for your reply.

but can you give me a suggestion to stop this?????

pranoy:
but can you give me a suggestion to stop this?????

Lose the 74' and do the whole thing in software....

how do u suggest i do it in software?????????????

i dont have enough pins

pranoy:
this is a rough sketch

So now do a proper one, showing each LED and the series resistor connected to each LED along with values.
In other words a schematic that people can understand.

What are you trying to achieve? You mentioned a traffic light. Do you mean that you only want one of the LED's on at a time or do you want the Yellow to light up when the Red AND Green are on?

You may want to use inverters as well if you want only one on at a time.

pranoy:
how do u suggest i do it in software?????????????

i dont have enough pins

Well so far you mentioned only the 3 LEDs, so that would need 3 i/o pins instead of the 2 you have used so far- how many LEDs do you need then?

(Btw a question is not going to get answered any faster with ??????????????? than just with ?)

I remmember once trying to dirrectly drive a seven segment display with my Arduino and the segments were really dim I checked and found that I forgot to put

pinMode(segment, OUTPUT);

!

Put the 01, 10, 11 as address bits into different logic - like a 74xx138, 74xx139 - selected out (#1, 2, 3) will go low, pull one cathode low.

I want the LED to be ON one at a time with the ouputs ( 01,10,11)

There is only one 220 ohm resistor at one of the output pins.

I don't have enough pins so i have to go with 2 pins itself.

the ???????????????? is something i got from chatting in fb.

There is only one 220 ohm resistor at one of the output pins.

You need another on the output of the logic gate.

this is a fair ckt dgm with only one yellow LED

thanks mike

but i tried it in a 2 way traffic scenario. but still the yellow light turns ON when Red comes in one of the tracks

What is IC1?

7408 and IC

i meant AND ic

What does it do?
The LEDs can all be driven thru the IO pins shown:

D1 = 1, D0 = 0 turns on LED1
D1 = 0, D0 = 1 turns on LED2
D1 = D0 turns LED1 & LED2 off
same for 3,4 5,6 7,8
What's the AND gate do that couldn't be done with another IO pin instead?

pranoy:
this is a fair ckt dgm with only one yellow LED

Regarding that diagram, the pins that go through a resistor to the LEDs should not be connected to the input of the AND gate, this should be connected directly to the arduino. I suspect that it is this that is causing a problem because the current flowing through that resistor is holding the input to the AND high and thus keeping the yellow on, which still needs its own series resistor.

cross roads

AND gate is for turning LED 3 ON D0-1 & D1-1