Frequency Converter

You're reading a microcontroller datasheet that lists timer ticks in megahertz, your oscilloscope is set to display in kilohertz, and the signal you're chasing was specified by a colleague in plain hertz. The conversion is straightforward — moves the decimal three places — but doing that math in your head while you're already debugging is how mistakes happen.

Drop in a value, pick the input unit, get the rest. Useful for radio work where frequencies span MHz to GHz, audio where everything sits between 20 Hz and 20 kHz, and clock-speed work where modern CPUs run in the gigahertz range. The conversion is purely metric prefix arithmetic — no precision is lost as long as your starting value has the precision you actually care about.

The scale runs in steps of 1,000: 1 kHz = 1,000 Hz, 1 MHz = 1,000,000 Hz, 1 GHz = 1,000,000,000 Hz, 1 THz = 10^12 Hz. Frequency is the count of complete cycles per second, and the hertz is named for Heinrich Hertz, who first demonstrated electromagnetic waves in the late 1880s. Period is the reciprocal of frequency: a 1 kHz signal completes a cycle every 1 millisecond, a 1 GHz signal every 1 nanosecond. The relationship matters because oscilloscopes often display period and frequency interchangeably and you need to know which axis you're looking at.

A worked example: your microcontroller has a 16 MHz crystal. That's 16,000,000 cycles per second, or one cycle every 62.5 nanoseconds. If you want to generate a 1 ms timer interrupt, you need to count 16,000 cycles between interrupts (16 MHz × 1 ms = 16,000). Drop a tick frequency into the converter, divide your target period by the resulting period, and you have your timer reload value. Off-by-one errors here are how PWM frequencies end up subtly wrong.

Where the simple conversion stops being enough: harmonics, sidebands, and bandwidth all involve frequencies, but they're properties of signals rather than single values. A 1 MHz square wave contains energy at 1 MHz, 3 MHz, 5 MHz, and so on — the odd harmonics. Bandwidth refers to the frequency range a system can handle, not a single frequency. And in radio work, channel spacing matters as much as the center frequency. The converter handles unit translation cleanly, but understanding what the frequency value actually represents in your specific context is on you. Treat the output as a unit conversion, not as a complete description of the signal you're working with.