This library enables you to use Interrupt from Hardware Timers on an ATmega4809-based boards, such as Arduino megaAVR : UNO WiFi Rev2, AVR_NANO_EVERY, etc.
As Hardware Timers are rare, and very precious assets of any board, this library now enables you to use up to 16 different ISR-based timers, while actually consuming only 1 Hardware Timer. Timers’ interval is very long (ulong millisecs). The most important feature is they’re ISR-based timers. Therefore, their executions are not blocked by bad-behaving functions or tasks. This important feature is absolutely necessary for mission-critical tasks.
Why do we need this megaAVR_TimerInterrupt Library
Imagine you have a system with a mission-critical function, measuring water level and control the sump pump or doing something much more important. You normally use asoftware timer to poll, or even place the function in loop(). But what if another function is blocking the loop() or setup().
So your function might not be executed on-time or not at all, and the result would be disastrous.
You’d prefer to have your function called, no matter what happening with other functions (busy loop, bug, etc.).
The correct choice is to use a Hardware Timer with Interrupt to call your function.
These hardware timers, using interrupt, still work even if other functions are blocking. Moreover, they are much more precise (certainly depending on clock frequency accuracy) than other software timers using millis() or micros(). That’s necessary if you need to measure some data requiring better accuracy.
Functions using normal software timers, relying on loop() and calling millis(), won’t work if the loop() or setup() is blocked by certain operation. For example, certain function is blocking while it’s connecting to WiFi or some services.
The catch is your function is now part of an ISR (Interrupt Service Routine), must be lean and mean, and follow certain rules. More to read on:
Inside the ISR function, delay() won’t work and the value returned by millis() will not increment. Serial data received while in the ISR function may be lost. You should declare as volatile any variables that you modify within the attached function.
Typically global variables are used to pass data between an ISR and the main program. To make sure variables shared between an ISR and the main program are updated correctly, declare them as volatile.
Initial Release v1.0.0
- Intial release to support to ATmega4809-based boards, such as Arduino UNO WiFi Rev2, AVR_NANO_EVERY, etc.
- New examples to support Blynk using WiFiNINA_Generic and Blynk_WiFiNINA_WM libraries.
Currently Supported Boards
- Arduino UNO WiFi Rev2, AVR_NANO_EVERY, etc.
- ATmega4809-based boards.