Breadboards are a useful tool for prototyping circuits.

Theory¶

Breadboard comprises of a grid of holes, with collections of holes electrically connected. Integrated circuits (dual in-line packages/DIP), leaded components (e.g. LED's, capacitors, resistors), connectors and wires can be inserted in to the holes, enabling circuit prototypes to be built without the need for soldering.

The diagram below shows the standard connections of a breadboard. All the rows of 5 holes are connected, but not across the central gap, and all the holes in the 4 colums are connected.

Breadboard connections¶

Default breadboard setup¶

The default breadboard setup used in our examples places the mbed Microcontroller at the top-center of the breadboard with the USB connector towards the edge.

Wires connect GND (pin 1) to the left vertical rail, and VOUT (pin 40) to the right vertical rail. This gives us 0v and 3.3v power rails on the left and right of the board, making the common task of wiring to power rails easy.

Breadboard schematic¶

Breadboard photo¶

Inserting an mbed into a breadboard¶

Note: The mbed Microcontroller is fragile, and inserting it in to breadboard will require some force; ensure you line up the holes, then press evenly until it goes in to the board fully.

Removing an mbed from a breadboard¶

Never try and remove the mbed Microcontroller by pulling on the USB lead or USB connector

You'll just pull off the connector itself!

It is best to leave the mbed Microcontroller in the board whenever possible; if you do need to remove it, be patient and do it carefully. Use a small jewelers screwdriver or similar, and lever it a bit at a time from each of the four corners in turn, ensuring you pull up with the screwdriver so you are pressing against the breadboard with the tip and the edge of the microcontroller with the shaft, rather than the tip touching the bottom of the microcontroller (which might damage the components on the underside).

So remember..

• Don't pull on the lead/connector (it will just pull off the connector; you should avoid there being force on the connector at all times)
• Don't pull it out from one side (you will bend the pins!)
• Don't lever the device where it touches the bottom of the microcontroller (there are lots of components there, and you will damage them!)

Where next¶