A time interval generator with the STM32 microcontroller

The paper presents a concept of utilization of counter-timer circuits built in popular microcontrollers for generating precise time intervals. The main aim was to generate pulses START and STOP wholly in hardware without using a core of the microcontroller. This enables minimizing the value of time jitter of the generated time intervals and allows the use of remaining resources of the microcontroller freely. The introduced method of generation exploits the possibility of simultaneous synchronization of TIM2 and TIM3 timers from an overloaded TIM1 timer. Dependent timers work in One Pulse Mode. START and STOP signals are generated by PWM channels of individual timers. PWM channels can be configured independently which gives the possibility to generate START and STOP pulses of different polarity and width. Generation of a time interval can be triggered automatically (TIM1) or through one of the inputs of the microcontroller. The implemented generator is characterized by the generated range of time interval from 0 to 100 s and the resolution of 40 ns. The jitter of 100 ps was obtained. The concept is suitable to apply in any microcontroller of the STM32 family. It allows the generation of precise and adjustable delays in the application without the need to significantly expand a hardware part of the device.