Interrupt Service Routine

“ISRs should decide when a task runs, not how it runs”

I have successfully refactored my Object Counter embedded firmware from a polling-based architecture to a Timer0 overflowinterrupt–driven design on the AVR platform.

Key improvements in this version:
Implemented Timer0 Overflow ISR to generate a precise system time base
Used the ISR strictly as a scheduler (tick generation + flag setting)
Moved all application logic (object detection, OLED updates) to the main loop
Achieved clean separation between real-time timing and application tasks
Improved determinism, scalability, and overall firmware structure

Technical highlights:
Bare-metal AVR programming
Interrupt Service Routine (ISR) best practices
Cooperative, flag-based task execution
HC-SR04 ultrasonic sensor integration
I²C OLED display handling outside ISR

This redesign helped reinforce a core embedded concept:
ISRs should decide when a task runs, not how it runs.
The ISR only sets flags; the main loop performs the actual work.

Linkedin post link:
https://www.linkedin.com/posts/anees-kokadan_timer0-overflow-interrupt-activity-7412291589454274560-xwxu?utm_source=social_share_send&utm_medium=member_desktop_web&rcm=ACoAABpp0PkBI2m3mwO5pKHlo96RE-5O-1S-AyY

Source code available on GitHub:
https://lnkd.in/gJW5whS7

Feedback and technical discussions are welcome.

hashtag#EmbeddedSystems hashtag#EmbeddedFirmware hashtag#AVR hashtag#BareMetal hashtag#Interrupts hashtag#ISR hashtag#Microcontrollers hashtag#FirmwareDesign hashtag#IoT hashtag#Electronics