Learning More about Electronics and Hardware on Your Raspberry Pi - dummies

Learning More about Electronics and Hardware on Your Raspberry Pi

By Richard Wentk

Part of Raspberry Pi For Kids For Dummies Cheat Sheet

Being able to design, build, and use your own extras is a big part of the appeal of small-board computers like the Raspberry Pi. Maybe you’ve heard of the Internet of Things? As a catchphrase, it means making computers that are small enough and cheap enough to plug into almost anything – as opposed to big desktop computers, tablets, and phones, which are expensive and really work only as computers.

The Pi is a good way to get started with the Internet of Things. If you know enough about electronics, you can plug almost anything into it, and maybe switch things on and off or control them in other ways too.

Electronic circuits send electricity around a circuit. Components in the circuit trap and herd the electricity so that it does useful stuff. You also need to know what the components do, and what the words mean. Here’s a quick guide to the words you’ll see:

  • Voltage measures how much of a kick the electricity has. If you have too much voltage, you can blow up a circuit. Some components have a “just right” voltage, and don’t work if the voltage is wrong.

  • Current (amperage) measures how much electricity is flowing. If you have too little, a circuit won’t work.

  • In a digital circuit, voltages are one of two levels – usually 0V and 5V, or 0V and 3.3V.

  • In an analog circuit, the voltage can be anywhere between a maximum (biggest) and minimum (smallest) range. When the voltage waggles around – for example, because it’s playing music – the waggle is called a signal. The range is often 1V to -1V. Sometimes it’s bigger.

  • Electronic parts come in two forms. You can buy components, which are individual bits and pieces. You need to know a lot about electronics to design your own circuits with bare components, so it’s usually easier to buy boards that have components soldered on to them to do a specific job.

  • A transistor is a component that can work as an electronic switch, or as an amplifier – a way to make a small signal bigger.

  • Technically, a resistor is a component that makes it harder for electricity to get from one part of a circuit to another. In practice, resistors are do-it-all components that set up transistors, sensors, and other semiconductors so they do a specific job.

  • Technically, a capacitor is a kind of mini-battery component that can charge up and discharge very quickly. Like resistors, capacitors have a lot of different uses.

  • A semiconductor chip is a component with a big mesh of transistors on a tiny sliver of silicon buried inside a plastic case. Chips do all kinds of clever things. There are literally tens of thousands of different chips!

  • A sensor is a chip that measures something. There are sensors for all kinds of applications – for example, you can measure temperature, humidity, air pressure, movement, light levels, and location on the Earth using the GPS (Global Positioning System).

  • Opto-electronics is a catchall name for electronic components that make light, including LEDS (Light Emitting Diodes), electroluminescent wires and panels, lasers, and the like.

  • Display are mini-screens. Technically they’re opto-electronic components, but if you’re looking to buy one, they often have their own section on websites. Some displays have touch sensors, so you can throw away your mouse. Displays are handy for stand-alone projects that don’t need a big computer screen.

  • Headers plug into the Pi’s pins. Sometimes they connect the pins to electronics on a board, but include an extra row of pins so that you can connect more stuff. Cables are . . . cables. Ribbon cables can connect to lots of pins at the same time, with a big flat pancake of cables. The cables often have different colors so that you can tell them apart.

So much for components. Here’s a list of boards you can buy:

  • Breakout boards. Make it easy to connect things to your Pi. Basically they “break out” wires or connectors from a small space you can’t get your fingers into, into a bigger space that’s easier to work with. They don’t usually do anything else.

  • HATs. A board that plugs directly on top of your Pi is called a HAT – because it’s a bit like a hat for your Pi (only not as cool as a real Fedora). You can buy all kinds of HATs, and they keep going in and out of stock.

  • RTC. Short for Real Time Clock – a board that remembers the time for your Pi when you power it down. (Don’t forget, the Pi gets the time from the Internet when it boots. No Internet? The time will be wrong – unless you have an RTC board.)

  • DAC and ADC. Short for Digital to Analog Converter and Analog to Digital Converter. A DAC outputs an analog voltage; an ADC measures an analog voltage. You can use both for general measuring duties or for recording and playing music.

  • Audio board. A board that’s designed for music and sound. Usually it includes an ADC for recording and a DAC for playing back. Because the Pi’s sound isn’t great, an audio board can do a lot to improve it.

  • Stepper motor driver. A big, beefy circuit that can drive a motor. Stepper motors literally step instead of turning smoothly. They’re good for making precise movements, so they’re often used in robots.