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TimerInterruptLEDDemo.ino
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TimerInterruptLEDDemo.ino
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/****************************************************************************************************************************
TimerInterruptLEDDemo.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.
*****************************************************************************************************************************/
/*
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.
*/
#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(ARDUINO_SAMD_CIRCUITPLAYGROUND_EXPRESS) || defined(__SAMD51__) || defined(__SAMD51J20A__) \
|| defined(__SAMD51J19A__) || defined(__SAMD51G19A__) || defined(__SAMD51P19A__) \
|| defined(__SAMD21E15A__) || defined(__SAMD21E16A__) || defined(__SAMD21E17A__) || defined(__SAMD21E18A__) \
|| defined(__SAMD21G15A__) || defined(__SAMD21G16A__) || defined(__SAMD21G17A__) || defined(__SAMD21G18A__) \
|| defined(__SAMD21J15A__) || defined(__SAMD21J16A__) || defined(__SAMD21J17A__) || defined(__SAMD21J18A__) )
#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
// Select only one to be true for SAMD21. Must must be placed at the beginning before #include "SAMDTimerInterrupt.h"
#define USING_TIMER_TC3 true // Only TC3 can be used for SAMD51
#define USING_TIMER_TC4 false // Not to use with Servo library
#define USING_TIMER_TC5 false
#define USING_TIMER_TCC false
#define USING_TIMER_TCC1 false
#define USING_TIMER_TCC2 false // Don't use this, can crash on some boards
// Uncomment To test if conflict with Servo library
//#include "Servo.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
#include "SAMDTimerInterrupt.h"
#include "SAMD_ISR_Timer.h"
// TC3, TC4, TC5 max permissible HW_TIMER_INTERVAL_MS is 1398.101 ms, larger will overflow, therefore not permitted
// Use TCC, TCC1, TCC2 for longer HW_TIMER_INTERVAL_MS
#define HW_TIMER_INTERVAL_MS 10
///////////////////////////////////////////////
#if (TIMER_INTERRUPT_USING_SAMD21)
#if USING_TIMER_TC3
#define SELECTED_TIMER TIMER_TC3
#elif USING_TIMER_TC4
#define SELECTED_TIMER TIMER_TC4
#elif USING_TIMER_TC5
#define SELECTED_TIMER TIMER_TC5
#elif USING_TIMER_TCC
#define SELECTED_TIMER TIMER_TCC
#elif USING_TIMER_TCC1
#define SELECTED_TIMER TIMER_TCC1
#elif USING_TIMER_TCC2
#define SELECTED_TIMER TIMER_TCC
#else
#error You have to select 1 Timer
#endif
#else
#if !(USING_TIMER_TC3)
#error You must select TC3 for SAMD51
#endif
#define SELECTED_TIMER TIMER_TC3
#endif
// Init selected SAMD timer
SAMDTimer ITimer(SELECTED_TIMER);
////////////////////////////////////////////////
// Init SAMD_ISR_Timer
// Each SAMD_ISR_Timer can service 16 different ISR-based timers
SAMD_ISR_Timer ISR_Timer;
#define TIMER_INTERVAL_1S 1000L
#define TIMER_INTERVAL_2S 2000L
#define TIMER_INTERVAL_5S 5000L
void TimerHandler(void)
{
ISR_Timer.run();
}
// In SAMD, avoid doing something fancy in ISR, for example complex Serial.print with String() argument
// The pure simple Serial.prints here are just for demonstration and testing. Must be eliminate in working environment
// Or you can get this run-time error / crash
void doingSomething1()
{
digitalWrite(LED_BUILTIN, !digitalRead(LED_BUILTIN));
Serial.println(F("G"));
}
void doingSomething2()
{
digitalWrite(LED_BLUE, !digitalRead(LED_BLUE));
Serial.println(F("B"));
}
void doingSomething3()
{
digitalWrite(LED_RED, !digitalRead(LED_RED));
Serial.println(F("R"));
}
void setup()
{
Serial.begin(115200);
while (!Serial && millis() < 5000);
delay(100);
Serial.print(F("\nStarting TimerInterruptLEDDemo 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"));
// Instantiate HardwareTimer object. Thanks to 'new' instanciation, HardwareTimer is not destructed when setup() function is finished.
//HardwareTimer *MyTim = new HardwareTimer(Instance);
// configure pin in output mode
pinMode(LED_BUILTIN, OUTPUT);
pinMode(LED_BLUE, OUTPUT);
pinMode(LED_RED, OUTPUT);
// Interval in millisecs
if (ITimer.attachInterruptInterval_MS(HW_TIMER_INTERVAL_MS, TimerHandler))
{
Serial.print(F("Starting ITimer OK, millis() = ")); Serial.println(millis());
}
else
Serial.println(F("Can't set ITimer. Select another freq. or timer"));
// Just to demonstrate, don't use too many ISR Timers if not absolutely necessary
// You can use up to 16 timer for each ISR_Timer
ISR_Timer.setInterval(TIMER_INTERVAL_1S, doingSomething1);
ISR_Timer.setInterval(TIMER_INTERVAL_2S, doingSomething2);
ISR_Timer.setInterval(TIMER_INTERVAL_5S, doingSomething3);
}
void loop()
{
/* Nothing to do all is done by hardware. Even no interrupt required. */
}