Circuit to Control 4 Bi-color LEDs using 3 Digital Pins of Arduino (Part 1 of 4)
We had already seen the circuit for controlling a bi-color LED using arduino mega in my previous post. But, if we want to control four bi-color LEDs, eight digital input / output pins of arduino mega is required to control eight cathode terminals of four bi-color LEDs. But, if we have ten bi-color LEDs, one arduino uno will not be enough since one arduino uno has only 13 digital input / output pins. Then, we have to go for more arduino unos which is practically not profitable. To avoid this we are using a simple technique in which many bi-color LEDs can be controlled using three digital input / output pins of arduino mega. We are using an 8 bit shift register IC 74595 for generating eight digital outputs from 3 digital input / output pins of arduino. Eight cathode terminals of these four bi-color LEDs are connected to the output pins of 74595 chip. Circuit is done as shown in the following diagram.
We will read about the circuit in next part.