Use this embedded-systems calculation to configure or check a timer, serial bus, ADC, PWM, buffer, power mode, flash budget, or watchdog from known clock and device parameters.

Start Bits

Required integer input.

Data Bits

Required integer input.

Parity Bits

Required integer input.

Stop Bits

Required integer input.

Bits on the wire per UART character from start, data, optional parity and stop bit counts; excludes idle time. The tool evaluates the supplied inputs together and returns the named outputs below; it does not infer omitted operating conditions or change the units shown.^[1]

Frame Bits

The resulting frame bits returned as an integer.

• Register widths, clock trees, prescalers, oscillator tolerance, interrupt latency, peripheral modes, voltage references, quantization, sleep states, endurance conditions, and silicon errata are device-specific.
• Use finite inputs in the displayed units and preserve more precision than the final presentation requires. Independently verify safety-critical, financial, compliance, or production decisions.

Confirm equations against the exact datasheet and reference manual, derive register values with integer rounding visible, and verify timing or voltage on hardware.

• SPI Transfer Time

  Ideal SPI clocking time for fixed-length frames, excluding chip-select setup, inter-frame delays and software overhead.

• I2C Bitrate

  Observed I²C SCL bit rate from measured high and low periods of one complete clock pulse.

• PWM Frequency

  Edge-aligned PWM frequency with an inclusive auto-reload value and effective prescaler divisor. On timers whose PSC register divides by PSC+1, enter PSC+1.