TeensyStep Fast Stepper Library

TeensyStep provides high-speed stepper control with the following capabilities:

The TeensyStepFTM namespace provides functions to manage hardware-backed delay channels used for timing interrupts. You can register a handler that implements the IDelayHandler interface to receive interrupt callbacks via addDelayChannel.

To use this, implement the delayISR(unsigned channel) method in a class derived from IDelayHandler. This method will be called when the timer reaches the specified delay value for that channel.

class MyHandler : public IDelayHandler {
public:
    void delayISR(unsigned channel) override {
        // Handle the interrupt for this specific channel
    }
};

MyHandler handler;
unsigned myChannel = TeensyStepFTM::addDelayChannel(&handler);
// ... later ...
TeensyStepFTM::removeDelayChannel(myChannel);

The step timer controls the frequency of motor steps. Use setStepFrequency to define the speed and stepTimerStart/stepTimerStop to control execution.

• setStepFrequency(unsigned f): Sets the step frequency in Hertz. Passing 0 will automatically stop the step timer.
• stepTimerStart(): Resumes and refreshes the step timer to ensure immediate start.
• stepTimerStop(): Pauses the step timer.
• stepTimerIsRunning(): Returns true if the step timer is currently active.
• getStepFrequency(): Returns the current timer clock frequency.

timerField.setStepFrequency(1000); // 1kHz
timerField.stepTimerStart();

if (timerField.stepTimerIsRunning()) {
    // ...
}

timerField.stepTimerStop();

The TimerControl class acts as the manager for all timer instances. To make a timer functional, it must be registered with the controller.

Workflow:

1. Call TimerControl::begin() once in your setup.
2. Create a PeriodicTimer or OneShotTimer instance.
3. Register the timer using TimerControl::attachTimer(timer_pointer).
4. Call TimerControl::tick() frequently in your main loop to process timer expirations.
5. Use TimerControl::detachTimer(timer_pointer) to remove a timer from the management list.

Note: TimerControl::tick() is the engine that drives the callbacks. If it is not called, timers will not fire.

PeriodicTimer myTimer([]() { /* task */ });

void setup() {
    TimerControl::begin();
    TimerControl::attachTimer(&myTimer);
    myTimer.setFrequency(10.0f);
    myTimer.start();
}

void loop() {
    TimerControl::tick();
}

Use rotateAsync() to command one or more steppers to rotate continuously without blocking the main execution loop. This method calculates Bresenham parameters for synchronized multi-motor rotation based on the vMax of each stepper and uses the lowest acceleration among the provided steppers.

You can pass steppers as a variadic list of arguments or as an array of pointers.

Note: The rotation is managed via an internal accelerator and timer ISR. The rotation continues until stopAsync() is called or the speed reaches zero.

// Using variadic arguments
controller.rotateAsync(stepper1, stepper2, stepper3);

// Using an array of stepper pointers
Stepper* motors[] = {&stepper1, &stepper2};
controller.rotateAsync(motors);

The PIT class allows fine-grained control over the timer's timing parameters:

• setFrequency(uint32_t val): Sets the timer frequency based on the bus frequency (F_BUS).
• setThisReload(uint32_t ldval): Sets the reload value (LDVAL) immediately for the current cycle.
• setNextReload(uint32_t ldval): Sets the reload value to be used for the next timer cycle.
• getLDVAL(): Returns the current reload value.
• getCVAL(): Returns the current compare value.

Before using any timers, you must call TimerControl::begin() to initialize the hardware cycle counter (DWT CYCCNT) on supported ARM Cortex-M processors. This enables the high-resolution timing mechanism used by the library.

TimerControl::begin();

Use these methods to track or manually override the stepper's current position.

• getPosition(): Returns the current position as an int32_t.
• setPosition(int32_t pos): Manually sets the current position value.

int32_t currentPos = myStepper.getPosition();

// Reset position to zero
myStepper.setPosition(0);

Use the following methods to query the state of the motor controller:

• isOk(): Returns true if the controller is in a valid state.
• isRunning(): Returns true if the step timer is currently active (motors are moving).
• isAllocated(): Returns true if the step timer has been allocated.
• getCurrentSpeed(): Returns the current step frequency (speed) of the motors.