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Periodic Callback Timers

Command	Description
`ItimerSet(intervalMs, callback)`	Sets the default timer's interval and callback.
`ItimerSet(timerNo, intervalMs, callback)`	Specifies the hardware timer to use.
`ItimerStart()`, `ItimerStart(timerNo)`	Starts the configured timer.
`ItimerStop()`, `ItimerStop(timerNo)`	Stops the timer.
`ItimerStopAll()`	Stops all callback timers.
`ItimerState()`, `ItimerState(timerNo)`	Returns the running state.

volatile bool task = false;
void onTimer() { task = true; }
void setup() { ItimerSet(100, onTimer); ItimerStart(); }
void loop() { if (task) { task = false; /* Actual work */ } }

Command Prototypes

Return Type	Command Prototype
`bool`	`ItimerSet(unsigned long intervalMs, void (*callback)())`
`bool`	`ItimerSet(uint8_t timerNumber, unsigned long intervalMs, void (*callback)())`
`bool`	`ItimerStart()`
`bool`	`ItimerStart(uint8_t timerNumber)`
`void`	`ItimerStop()`
`void`	`ItimerStop(uint8_t timerNumber)`
`void`	`ItimerStopAll()`
`bool`	`ItimerState()`
`bool`	`ItimerState(uint8_t timerNumber)`

Callbacks run in interrupts. Change only flags in callbacks; do not use delay(), Serial, I²C, SPI or lengthy calculations. Also check whether the timer is shared with PWM.

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