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SwitchDebounce.ino
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/****************************************************************************************************************************
SwitchDebounce.ino
For SAMD boards
Written by Khoi Hoang
Built by Khoi Hoang https://github.com/khoih-prog/SAMD_TimerInterrupt
Licensed under MIT license
Now even you use all these new 16 ISR-based timers,with their maximum interval practically unlimited (limited only by
unsigned long miliseconds), you just consume only one SAMD timer and avoid conflicting with other cores' tasks.
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.
Based on SimpleTimer - A timer library for Arduino.
Author: [email protected]
Copyright (c) 2010 OTTOTECNICA Italy
Based on BlynkTimer.h
Author: Volodymyr Shymanskyy
Version: 1.5.0
Version Modified By Date Comments
------- ----------- ---------- -----------
1.0.0 K Hoang 30/10/2020 Initial coding
1.0.1 K Hoang 06/11/2020 Add complicated example ISR_16_Timers_Array using all 16 independent ISR Timers.
1.1.1 K.Hoang 06/12/2020 Add Change_Interval example. Bump up version to sync with other TimerInterrupt Libraries
1.2.0 K.Hoang 08/01/2021 Add better debug feature. Optimize code and examples to reduce RAM usage
1.3.0 K.Hoang 02/04/2021 Add support to Sparkfun SAMD21 and SAMD51 boards
1.3.1 K.Hoang 09/05/2021 Fix compile error to some SAMD21-based boards
1.4.0 K.Hoang 02/06/2021 Fix SAMD21 rare bug caused by not fully init Prescaler
1.5.0 K.Hoang 08/10/2021 Improve frequency precision by using float instead of ulong
*****************************************************************************************************************************/
/*
Notes:
Special design is necessary to share data between interrupt code and the rest of your program.
Variables usually need to be "volatile" types. Volatile tells the compiler to avoid optimizations that assume
variable can not spontaneously change. Because your function may change variables while your program is using them,
the compiler needs this hint. But volatile alone is often not enough.
When accessing shared variables, usually interrupts must be disabled. Even with volatile,
if the interrupt changes a multi-byte variable between a sequence of instructions, it can be read incorrectly.
If your data is multiple variables, such as an array and a count, usually interrupts need to be disabled
or the entire sequence of your code which accesses the data.
Switch Debouncing uses high frequency hardware timer 50Hz == 20ms) to measure the time from the SW is pressed,
debouncing time is 100ms => SW is considered pressed if timer count is > 5, then call / flag SW is pressed
When the SW is released, timer will count (debounce) until more than 50ms until consider SW is released.
We can set to flag or call a function whenever SW is pressed more than certain predetermined time, even before
SW is released.
*/
#if !( defined(ARDUINO_SAMD_ZERO) || defined(ARDUINO_SAMD_MKR1000) || defined(ARDUINO_SAMD_MKRWIFI1010) \
|| defined(ARDUINO_SAMD_NANO_33_IOT) || defined(ARDUINO_SAMD_MKRFox1200) || defined(ARDUINO_SAMD_MKRWAN1300) || defined(ARDUINO_SAMD_MKRWAN1310) \
|| defined(ARDUINO_SAMD_MKRGSM1400) || defined(ARDUINO_SAMD_MKRNB1500) || defined(ARDUINO_SAMD_MKRVIDOR4000) || defined(__SAMD21G18A__) \
|| defined(ARDUINO_SAMD_CIRCUITPLAYGROUND_EXPRESS) || defined(__SAMD21E18A__) || defined(__SAMD51__) || defined(__SAMD51J20A__) || defined(__SAMD51J19A__) \
|| defined(__SAMD51G19A__) || defined(__SAMD51P19A__) || defined(__SAMD21G18A__) )
#error This code is designed to run on SAMD21/SAMD51 platform! Please check your Tools->Board setting.
#endif
// These define's must be placed at the beginning before #include "SAMDTimerInterrupt.h"
// _TIMERINTERRUPT_LOGLEVEL_ from 0 to 4
// Don't define _TIMERINTERRUPT_LOGLEVEL_ > 0. Only for special ISR debugging only. Can hang the system.
// Don't define TIMER_INTERRUPT_DEBUG > 2. Only for special ISR debugging only. Can hang the system.
#define TIMER_INTERRUPT_DEBUG 0
#define _TIMERINTERRUPT_LOGLEVEL_ 0
#include "SAMDTimerInterrupt.h"
//#ifndef LED_BUILTIN
// #define LED_BUILTIN 13
//#endif
#ifndef LED_BLUE
#define LED_BLUE 2
#endif
#ifndef LED_RED
#define LED_RED 8
#endif
unsigned int SWPin = 7;
#define TIMER1_INTERVAL_MS 20
#define DEBOUNCING_INTERVAL_MS 100
#define LONG_PRESS_INTERVAL_MS 5000
#define LOCAL_DEBUG 1
// Depending on the board, you can select SAMD21 Hardware Timer from TC3-TCC
// SAMD21 Hardware Timer from TC3 or TCC
// SAMD51 Hardware Timer only TC3
// Init SAMD timer TIMER_TC3
SAMDTimer ITimer(TIMER_TC3);
#if (TIMER_INTERRUPT_USING_SAMD21)
// Init SAMD timer TIMER_TCC
//SAMDTimer ITimer(TIMER_TCC);
#endif
volatile bool SWPressed = false;
volatile bool SWLongPressed = false;
void TimerHandler()
{
static unsigned int debounceCountSWPressed = 0;
static unsigned int debounceCountSWReleased = 0;
#if (TIMER_INTERRUPT_DEBUG > 1)
static unsigned long SWPressedTime;
static unsigned long SWReleasedTime;
unsigned long currentMillis = millis();
#endif
static bool started = false;
if (!started)
{
started = true;
pinMode(SWPin, INPUT_PULLUP);
}
if ( (!digitalRead(SWPin)) )
{
// Start debouncing counting debounceCountSWPressed and clear debounceCountSWReleased
debounceCountSWReleased = 0;
if (++debounceCountSWPressed >= DEBOUNCING_INTERVAL_MS / TIMER1_INTERVAL_MS)
{
// Call and flag SWPressed
if (!SWPressed)
{
#if (TIMER_INTERRUPT_DEBUG > 1)
SWPressedTime = currentMillis;
Serial.print("SW Press, from millis() = "); Serial.println(SWPressedTime - DEBOUNCING_INTERVAL_MS);
#endif
SWPressed = true;
// Do something for SWPressed here in ISR
// But it's better to use outside software timer to do your job instead of inside ISR
//Your_Response_To_Press();
}
if (debounceCountSWPressed >= LONG_PRESS_INTERVAL_MS / TIMER1_INTERVAL_MS)
{
// Call and flag SWLongPressed
if (!SWLongPressed)
{
#if (TIMER_INTERRUPT_DEBUG > 1)
Serial.print("SW Long Pressed, total time ms = "); Serial.print(currentMillis);
Serial.print(" - "); Serial.print(SWPressedTime - DEBOUNCING_INTERVAL_MS);
Serial.print(" = "); Serial.println(currentMillis - SWPressedTime + DEBOUNCING_INTERVAL_MS);
#endif
SWLongPressed = true;
// Do something for SWLongPressed here in ISR
// But it's better to use outside software timer to do your job instead of inside ISR
//Your_Response_To_Long_Press();
}
}
}
}
else
{
// Start debouncing counting debounceCountSWReleased and clear debounceCountSWPressed
if ( SWPressed && (++debounceCountSWReleased >= DEBOUNCING_INTERVAL_MS / TIMER1_INTERVAL_MS))
{
#if (TIMER_INTERRUPT_DEBUG > 1)
SWReleasedTime = currentMillis;
// Call and flag SWPressed
Serial.print("SW Released, from millis() = "); Serial.println(SWReleasedTime);
#endif
SWPressed = false;
SWLongPressed = false;
// Do something for !SWPressed here in ISR
// But it's better to use outside software timer to do your job instead of inside ISR
//Your_Response_To_Release();
// Call and flag SWPressed
#if (TIMER_INTERRUPT_DEBUG > 1)
Serial.print("SW Pressed total time ms = "); Serial.println(SWReleasedTime - SWPressedTime);
#endif
debounceCountSWPressed = 0;
}
}
}
void setup()
{
Serial.begin(115200);
while (!Serial);
delay(100);
Serial.print(F("\nStarting SwitchDebounce on ")); Serial.println(BOARD_NAME);
Serial.println(SAMD_TIMER_INTERRUPT_VERSION);
Serial.print(F("CPU Frequency = ")); Serial.print(F_CPU / 1000000); Serial.println(F(" MHz"));
// Interval in microsecs
if (ITimer.attachInterruptInterval(TIMER1_INTERVAL_MS * 1000, TimerHandler))
{
Serial.print(F("Starting ITimer OK, millis() = ")); Serial.println(millis());
}
else
Serial.println(F("Can't set ITimer. Select another freq. or timer"));
}
void loop()
{
}