The pitch of a connector is the distance measured from center of one pin to the center of the next pin. The pitch is important to pay attention to when designing a circuit or purchasing connectors, lets just say it out loud, because if the pitch of one side of the connector does not match the other half, it won’t fit. It can be confusing because nomenclature and standards get mixed and matched.
A famous example of header (connector) spacing gone wrong is the Arduino Uno board. All of the individual headers are ok, but the spacing between two of the headers is too close. It is very common keep the spacing between headers on the same grid or spacing to allow for connections to the board with a single header to another board (a shield in the Arduino universe). The offset header spacing forces designers and manufacturers to continue the error to be compatible.
Another possible thing to trip up on is that families of connectors will look the same and have the same design features, but be different pitches. The reason for the different pitches is that as manufacturing has become more advanced, connectors can be made smaller. Sometimes the connections are only carrying low amounts of current and voltage, so they can be made smaller to save space and material costs. Other times the power being conducted requires connections and wires with a higher capacity. Datasheets and catalog references can help with making sure you have the right pitch. Connectors are often keyed as well to prevent plugging it in the wrong way and reversing polarity or making other connections that shouldn’t be made.
Here are a couple of the most common pitches in metric and standard units:
- 0.1 inches = 2.54mm (standard for breadboards)
- 0.05 inches = 1.27mm
There are many other pitches out there that are larger and smaller:
So keep pitch of connectors and compatibility in mind when you are purchasing connectors, headers, motherboards, daughterboards and accessories and your project will go off without a ... pitch.