2.2 The Breadboard

The first task that I'm going to show you how to do is to set up the microcontroller board on a breadboard. So first, let me tell you how breadboards work. Here is a diagram that should match the breadboard that you have:


The key to understand how to work with a breadboard is to visualize the internal connections between the holes. Once you know which holes are internally connected, you know that you can create a connection between two pins by inserting them in a pair of connected holes. It's really that simple.

Below I created a diagram that shows these internal connections between holes:

Breadboard wiring

The top two and top bottom rows of holes are usually referred to as the "power strips", and they actually work in a similar way to a household power strip. For example, when you connect a pin that delivers current (such as any of the 3.3V pins in the ESP8266 board) into any of the holes in the top row, then all the remaining holes in that row can be used by other devices to draw power for themselves, so effectively this is equivalent to having a direct connection between each device and the power source. This top line is marked with a red line and in some breadboards with a "+" label, which indicates that as a convention, it should be used for current, as in my example. The second row of holes is marked in blue and with a "-" label. The convention is to use this line as a ground connection. There are two more positive and negative power strips at the bottom of the breadboard.

The connections used by the holes in the middle are more tricky to understand. Here the holes are grouped in fives. The ten rows of holes in the two middle sections are labeled with the letters a through j, but unlike the power strip rows, these rows are not connected. The connections for these pins are vertical, and cover just the group of five vertical holes in each section. The columns are labeled from 1 to 30, but in many breadboards you can only see a label every five columns. Using these labels, you can see that the a1, b1, c1, d1, and e1 holes are all connected with each other, so any pins that are plugged into these holes will be all connected. Similarly, pins f1, g1, h1, i1 and j1 are connected between them, but they do not share a connection with the top five holes.

If you think this is starting to make sense, you are ready to install the microcontroller into the breadboard. Depending on the physical dimensions of your microcontroller, there are two possible ways to do this.

Most likely you have a newer microcontroller board, which is the smaller kind. To find out for sure, place the breadboard on your desk with a red power strip on top and column 1 to the right, and then see if you can align your microcontroller in the middle section, with the micro-USB port facing right. Do not insert it into the breadboard yet. The top 15 pins from the microcontroller should be in the b row of your breadboard, columns 1 on the right to 15 on the left. The bottom strip of microcontroller pins should be aligned with the i row. The a and j rows should be free and visible from the top. Here is a diagram:

ESP8266 on Breadboard

If you were able to align the pins as shown in the diagram, then gently press on the board until the pins are fully inserted into the holes. If your microcontroller is too large to fit in the way I described, then you have one of the bigger boards. These work in exactly the same way as the newer counterparts, but have slightly larger dimensions, which means that there is no way to fit them in the middle section of the breadboard while leaving at least a row on each side to make connections. The solution that I have used for these boards is to straddle them across two breadboards, as show in the diagram below:

ESP8266 on Two Breadboards

With this set up, the top row of pins in the microcontroller board is in row j of the top breadboard, and each pin has four free holes to make connections. The bottom row of microcontroller pins fits in the a row of the bottom breadboard, also leaving four holes for connections to each pin.

In the diagrams that follow I'm going to assume you have the newer and smaller board installed on a single breadboard, since the older boards are mostly out of circulation by now.

Complete and Continue