Using 3 seperate IR leds with one Data Pin (Pin 9) on Arduino Mega 256

Using Arduino LEDs and Multiplexing
1

Good afternoon,

I cannot get my head around this! So i seek your help and knowledge! My setup:

I got one Arduino 2560, with an ethernet card on it. I build a web interface, where i can use Klik/aan - Klik/uit emitter at 433 Hertz AM. I also can use a 16 relais board with the web interface and i can send IR signals with the same web interface.

I hoped that the IR signals for my LED string and HDMI switches where different, but unformtunally, some colors are the same for hdmi channel 1 and 5. Bummer. So i thought why not have sperate IR Leds and send the signals seperate.

Since i do not got much IO, but a lot of digital outs on the board i thought, why not switch the ground on for 1 IR led and of for the other two. Send the signal, tie the IR led to the receiver. And the other IR led to another IR receiver.

Then i found this topic:
https://github.com/z3t0/Arduino-IRremote/issues/128

Also see the attachment for the picture.

This is what is said about this option:

I tested it with "standart" one IR LED library. All LED's are connected to D3 and the other pin - to digital outputs of Adruino. Then we manipulate digital outputs. You need to turn on / off these outputs before sending the IR signal to LED... You can use many IR LED's (limits only Arduino I/O quantity)

I dont understand how i can manipulate the output as inputs and turn them of, i think i don't understand this concept.

Can anybody help me with some examples and what does he mean?

Thankyou!

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2

Forget it. It is a flawed concept.

Using three LEDs and switching the common from them puts three times more current through that pin and thus pushes you over the limit of current for a pin. At least you need a transistor for the PWM output. And if you do that the signals will be inverted.

If you want to drive more LEDs with the same signal just use a transistor to invert the signal and a transistor to drive the three LEDs. You can then use smaller resistors and get even mor IR light.