RPI_PICO_TimerInterrupt Library

RPI_PICO_TimerInterrupt library GitHub release
How To Install Using Arduino Library Manager


Features

This library enables you to use Interrupt from Hardware Timers on on RP2040-based boards such as RASPBERRY_PI_PICO, using Earle Philhower's arduino-pico core. Support to Arduino-mbed RP2040 core will be added in future releases.

As Hardware Timers are rare, and very precious assets of any board, this library now enables you to use up to 16 ISR-based Timers, while consuming only 1 Hardware Timer. Timers' interval is very long (ulong millisecs).

Now with these new 16 ISR-based timers, the maximum interval is practically unlimited (limited only by unsigned long miliseconds) while the accuracy is nearly perfect compared to software timers.

The most important feature is they're ISR-based timers. Therefore, their executions are not blocked by bad-behaving functions / tasks. This important feature is absolutely necessary for mission-critical tasks.

The ISR_Timers_Array_Simple example will demonstrate the nearly perfect accuracy compared to software timers by printing the actual elapsed millisecs of each type of timers.

Being ISR-based timers, their executions are not blocked by bad-behaving functions / tasks, such as connecting to WiFi, Internet and Blynk services. You can also have many (up to 16) timers to use.

This non-being-blocked important feature is absolutely necessary for mission-critical tasks.

You'll see blynkTimer Software is blocked while system is connecting to WiFi / Internet / Blynk, as well as by blocking task
in loop(), using delay() function as an example. The elapsed time then is very unaccurate

Why using ISR-based Hardware Timer Interrupt is better

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 a software 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, 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), and must be lean / mean, and follow certain rules. More to read on:

HOWTO Attach Interrupt


Currently supported Boards

  1. RP2040-based boards such as RASPBERRY_PI_PICO, ADAFRUIT_FEATHER_RP2040 and GENERIC_RP2040, etc.


Changelog

Initial Releases v1.0.0

  1. Initial coding to support RP2040-based boards such as RASPBERRY_PI_PICO, etc. using Earle Philhower's arduino-pico core

Examples:

  1. Argument_Complex
  2. Argument_None
  3. Argument_Simple
  4. Change_Interval
  5. ISR_16_Timers_Array_Complex
  6. ISR_Timers_Array_Simple
  7. RPM_Measure
  8. SwitchDebounce
  9. TimerInterruptTest
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Releases v1.1.0

  1. Add support to new boards (ADAFRUIT_ITSYBITSY_RP2040, ADAFRUIT_QTPY_RP2040, ADAFRUIT_STEMMAFRIEND_RP2040, ADAFRUIT_TRINKEYQT_RP2040, ADAFRUIT_MACROPAD_RP2040, SPARKFUN_PROMICRO_RP2040, etc.) using the arduino-pico core
  2. Add ISR_16_Timers_Array_Complex examples.
  3. Fix examples' bug