STM32 Timer Calculator
Just enter the duration — automatically calculate PSC, ARR and CCR values. Clock chain analysis, error rate and ready-to-use C code generation.
STM32 Timer Calculator
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What does this tool do?
Using the timer (counter) peripheral on STM32 microcontrollers requires correctly calculating PSC (Prescaler) and ARR (Auto-Reload Register) values. These values form the foundation of dozens of applications — PWM generation, servo control, ultrasonic distance measurement, motor driver signals, or interrupts triggered at precise intervals.
The tool automatically calculates the clock chain (SYSCLK → AHB → APB → Timer), applies the rule that the timer receives 2× the clock when APB prescaler > 1, and finds the optimal PSC/ARR combination with the lowest error rate. The same formulas apply to STM32F1, F2, F3, F4 and L4 series.
Core formulas
f_timer = f_APB_eff / (PSC + 1)f_overflow = f_timer / (ARR + 1)Duty (%) = CCR / (ARR + 1) × 100If APB div > 1: f_APB_eff = f_APB × 2