A common-cathode RGB LED has a total of four pins. One of the pins is the cathode which must be connected to ground and the others each control a color. The pinout shown below is for a typical RGB LED. Notice that each of the pins is a slightly different length; the cathode is the

Let’s say you are working on a project that requires you to turn on an appliance plugged into a household main (115-ish V AC) using an Arduino (3.3-5 V DC). What would you use as a switch. For some applications you can use a bipolar junction transistor as a switch (see this post). However, such

A fine way to compactly control multiple Arduino digital output pins is to use a byte in conjunction with a bitmap. The byte provides the structure (eight bits) to compactly specify which digital pins are turned on and which are turned off. Let’s consider an example. Suppose you have eight digital output pins to control,

An Arduino project I am working on uses the TinyGPS library and an EM-406A GPS receiver to keep track of the date and time. This data is used by the rest of my program. When I was coding up this project, I ran in numerous bugs and believe the cause was derived from serial communication

The Arduino Uno (ATmega328) has a single hardware serial connection. If more serial connections are needed, you must implement these in software. Luckily, there is a very easy to use library to implement software serial connections. It is called SoftwareSerial.h and is included with the latest Arduino IDE. The following code demonstrates how to use