Voice Prompt Module with Integrated MP3 Player and Speaker

Jargon buster

Plain-language definitions for the technical terms used above.

DAC

A digital-to-analogue converter turns numbers from the microcontroller into a real analogue voltage. It matters if you want to generate simple waveforms, audio-style signals, or variable control voltages rather than just on/off outputs.

DC

DC means direct current, where electricity flows in one constant direction, as supplied by batteries, USB ports and many plug-pack power supplies. When a product specifies DC, it runs from a DC supply rather than mains AC, so you need to provide the correct voltage and polarity.

Impedance

Impedance is the total opposition a component or circuit presents to alternating current, measured in ohms, combining resistance with frequency-dependent reactance. It appears in many contexts, such as matching a speaker's impedance (for example 4 ohm or 8 ohm) to an amplifier or the input and output impedance of signal circuits, and a correct match helps avoid weak signals, distortion or damage.

IoT

Short for Internet of Things, meaning physical devices that connect to networks or the internet to send data or be controlled remotely. It matters if you want projects such as connected sensors, remote controls or classroom data-logging activities.

TTL serial

A simple serial data connection that uses microcontroller logic-level voltages (typically 3.3 V or 5 V) rather than the higher, inverted voltages of computer RS-232. When a device lists TTL serial, it can usually wire straight to a microcontroller's UART pins or to a USB-to-TTL serial adapter, but it needs a level converter before connecting to a true RS-232 port.