![]() OCRo = ((CntFreq/2)*sqrt((2*mmPerStep)/Accel)) // calculate first OCR value based on acceleration OCRmin = ((mmPerStep*(CntFreq/2))/MaxSpeed) // calculate minimum OCR value based on maxSpeed If (stepsTaken % speedIncreaseStepInterval = 0) ![]() If (stepsTaken = (numSteps - decelSteps)) #define StartTimer3 TCCR3B |= (1= numSteps) Here is an example sketch that can be used to reproduce the "ramp frequency" of the stepper motor, by varying the OCR value from within the output compare ISR (again using timer 3 in this sketch): #include "math.h" StopDrive() member function has been called on the object from somewhere else in the code (based on hierarchical State Machine conditions).Step target for the object exists and has been reached (handled by ISR).The reason I want to use timers for the step pulse is to free up the mega for other tasks in between speed ramps and counting steps (hierarchical state machine).īased on my "simple sketch" trials (prior to writing the CL42T class), I concluded that I can set up the timers and an OCR array for the desired movement, start the movement, and then simply monitor for the end of the domino line via one of two stop conditions: The dual motor subassemblies are strategically placed on the same timer as the motors need to be synchronized while running, and I can toggle both output compare pins on a single timer at the same frequency, given the appropriate bits are set in the TCCRA register. The final application will have a total of seven stepper drives, using the following timer outputs: In this application, each stepper motor has it's own dedicated timer output pin. ![]() The OCnx behaviors for CTC mode are detailed in table 17-3 on page 155 of the datasheet. Furthermore, in "Compare Output Mode, non-PWM", the output compare pins (in my particular test case, OC3A) can be toggled on compare match by setting the appropriate COMnx bits in the TCCRA register. "CTC" is the "clear timer on compare match" mode (table 17-2 on page 145, and section 17.9.2 starting on page 145), wherein the timer/counter increments until TCNT matches OCR or ICR, sets an output compare match flag (and calls the associated interrupt if enabled in TIMSK), then resets TCNT from zero. More specifically, Chapter 17, section 9, explains the modes of the timers. The way I understand the information in the datasheet, the OCR and ICR registers can be manipulated via interrupts, and (EDIT: bold) placing the timer in CTC output toggle mode will cause changes to the OCR or ICR value to affect the frequency of the rising edge of the pulses. This is not recommended because you bypass the LD1117S50CTR 5V voltage regulator and have to make sure that the voltage level is stable.How do you intend to let multiple steppers run at different step rates?Īgreed - it is explained in great detail in the datasheet. You can also power power the Arduino microcontroller from the 5V pin. You cannot power the board with the barrel jack and VIN GPIO at the same time, because there is a polarity protection diode, connecting between the positive of the barrel jack to the VIN pin, rated at 1A. Therefore you are able to power the Uno with an external 9 Volt battery. The voltage has to be between 7V and 12V.
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