countertimer

A countertimer is a hardware peripheral that combines the capabilities of a counter and a timer. It can count discrete events or clock cycles and can generate timing signals based on counts or elapsed time. They are common in microcontrollers, digital signal processors, and system-on-chip devices, where precise timing and event measurement are required.

A typical countertimer includes a clock input, an optional prescaler, one or more counter registers, and one or more capture and compare units. In timer mode, the counter increments with each clock tick until it reaches a defined value, at which point it can generate an interrupt or an output pulse and often auto-reloads. In counter mode, the counter increments in response to external events rather than the internal clock. Many devices support input capture to record the timer value when an external edge occurs, and output compare to drive signals or generate PWM.

Common features include: programmable prescaler, auto-reload or one-shot modes, multiple channels, interrupt or DMA request generation, and the ability to cascade multiple timers for longer timebases or higher resolution. Some countertimers offer watchdog or sleep modes and clock-domain isolation for power efficiency.

Typical uses include scheduling software tasks, generating periodic interrupts for real-time operating systems, measuring pulse widths and frequencies, creating PWM signals for motor control or power electronics, and timestamping events in data acquisition. Proper configuration requires consideration of clock stability, overflow handling, and synchronization with other peripherals.