The ATmega328 has a total of three input/output ports, port B, port C, and port D. Two of these ports, namely port B and port D, are associated with the 14 digital input/output pins on the Arduino Uno. Port C is associated with the analog input pins which can also be used as digital input/output

Serial communication is a method for two computers or microcontrollers (or one computer and a microcontroller) to talk to one another. Arduino uses the transistor-transistor logic (TTL) serial protocol. This protocol sends bits using voltages of zero (for a zero bit) and five (for a one bit). Another popular serial protocol is RS-232 which uses

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,