Analog-to-digital converter (ADC)
A circuit that samples a continuous analog voltage and converts it into a digital number a processor can store, process and transmit.
An ADC turns the voltage from an analog sensor into a value firmware can use. Its resolution, in bits, sets how finely the input range is divided, and its sampling rate sets how often it looks. Most microcontrollers include a modest ADC suitable for slow signals; precise measurements of load cells, vibration or biosignals usually need an external converter with better resolution and noise performance.
The digital number is only as good as the analog path in front of it. Reference voltage accuracy, wiring noise, sensor impedance and the stability of the supply all show up as error, and a 12-bit reading on a noisy board can carry fewer real bits than its resolution suggests. Many digital sensors sidestep this by integrating an ADC next to the sensing element and reporting results over I2C or SPI.
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