Sampling, PWM & Conversion

Sampling, PWM & Conversion

Use this page to revise how analogue reality becomes numbers — and how numbers become analogue-ish outputs.

Sampling

The ADC converts a voltage to an integer. Nyquist: sample faster than twice the highest frequency you care about, or you alias. Resolution (bits) and reference voltage set the step size.

PWM

Pulse-width modulation encodes a value in duty cycle (fraction of time high). Averaged with a motor or LED inertia it looks like analogue. Frequency vs. duty cycle are different knobs.

DAC and drivers

A DAC outputs a voltage. Many MCUs fake analogue with PWM instead. Power devices still need a driver; PWM into a MOSFET gate is not the same as PWM into a speaker without a filter.

Starting Points

• Sensors, actuators & PWM
• Electronics fundamentals

Key Points

• You can explain what an ADC reading means given Vref and bit width.
• You can state the Nyquist idea and what aliasing is.
• You can define PWM duty cycle and give one use (LED brightness, servo, motor).
• You can explain why a driver stage is needed between an MCU pin and a motor.