Interface Stepper motor with STM32

A stepper motor divides full rotation into number of equal steps. It finds great application in the fields of Robotics. Today, in this tutorial, we will learn how to interface stepper motor with STM32.

Stepper motors generally comes along with an IC ULN2003. This IC is used to drive motor because microcontroller pins are unable to provide sufficient current to drive these motors. There are three different types of stepping modes used for stepper motors:-

• Wave Drive
• Full Drive
• Half Drive

Wave Drive

In this mode only one stator electromagnet is energized at a time. It has the same number of steps as the full step drive. The motor takes 2048 STEPS to complete 1 revolution, which means 2048/4 = 512 sequences per Revolution.

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Full Drive

In this mode two stator electromagnets are energized at a time and the motor runs at full torque. Two phases are energized at the same time, and motor have more Torque than the Wave Drive. The motor takes 2048 STEPS to complete 1 revolution, which means 2048/4 = 512 sequences per Revolution.

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Half Drive

In this mode, one and two phases are energized alternatively. This mode is used to increase the angular resolution of the motor but the torque is reduced. The Torque remains somewhere in between the Wave Drive and Full Drive. The motor takes 4096 STEPS to complete 1 revolution, which means 2048/8 = 512 sequences per Revolution.

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Some Insight into the CODE

void delay (uint16_t us)
{
  __HAL_TIM_SET_COUNTER(&htim1, 0);
  while (__HAL_TIM_GET_COUNTER(&htim1) < us);
}

First of all create the delay in microseconds. If you don’t understand this part goto https://controllerstech.com/create-1-microsecond-delay-stm32/

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#define stepsperrev 4096

Define the number of steps the motor takes for 1 revolution

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void stepper_set_rpm (int rpm)  // Set rpm--> max 13, min 1,,,  went to 14 rev/min
{
	delay(60000000/stepsperrev/rpm);
}

The above function to set the RPM of the Motor. We have to use it instead of delay.

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void stepper_half_drive (int step)
{
	switch (step){
		case 0:
			  HAL_GPIO_WritePin(GPIOA, GPIO_PIN_1, GPIO_PIN_SET);   // IN1
			  HAL_GPIO_WritePin(GPIOA, GPIO_PIN_2, GPIO_PIN_RESET);   // IN2
			  HAL_GPIO_WritePin(GPIOA, GPIO_PIN_3, GPIO_PIN_RESET);   // IN3
			  HAL_GPIO_WritePin(GPIOA, GPIO_PIN_4, GPIO_PIN_RESET);   // IN4
			  break;

		case 1:
			  HAL_GPIO_WritePin(GPIOA, GPIO_PIN_1, GPIO_PIN_SET);   // IN1
			  HAL_GPIO_WritePin(GPIOA, GPIO_PIN_2, GPIO_PIN_SET);   // IN2
			  HAL_GPIO_WritePin(GPIOA, GPIO_PIN_3, GPIO_PIN_RESET);   // IN3
			  HAL_GPIO_WritePin(GPIOA, GPIO_PIN_4, GPIO_PIN_RESET);   // IN4
			  break;

		case 2:
			  HAL_GPIO_WritePin(GPIOA, GPIO_PIN_1, GPIO_PIN_RESET);   // IN1
			  HAL_GPIO_WritePin(GPIOA, GPIO_PIN_2, GPIO_PIN_SET);   // IN2
			  HAL_GPIO_WritePin(GPIOA, GPIO_PIN_3, GPIO_PIN_RESET);   // IN3
			  HAL_GPIO_WritePin(GPIOA, GPIO_PIN_4, GPIO_PIN_RESET);   // IN4
			  break;

		case 3:
			  HAL_GPIO_WritePin(GPIOA, GPIO_PIN_1, GPIO_PIN_RESET);   // IN1
			  HAL_GPIO_WritePin(GPIOA, GPIO_PIN_2, GPIO_PIN_SET);   // IN2
			  HAL_GPIO_WritePin(GPIOA, GPIO_PIN_3, GPIO_PIN_SET);   // IN3
			  HAL_GPIO_WritePin(GPIOA, GPIO_PIN_4, GPIO_PIN_RESET);   // IN4
			  break;

		case 4:
			  HAL_GPIO_WritePin(GPIOA, GPIO_PIN_1, GPIO_PIN_RESET);   // IN1
			  HAL_GPIO_WritePin(GPIOA, GPIO_PIN_2, GPIO_PIN_RESET);   // IN2
			  HAL_GPIO_WritePin(GPIOA, GPIO_PIN_3, GPIO_PIN_SET);   // IN3
			  HAL_GPIO_WritePin(GPIOA, GPIO_PIN_4, GPIO_PIN_RESET);   // IN4
			  break;

		case 5:
			  HAL_GPIO_WritePin(GPIOA, GPIO_PIN_1, GPIO_PIN_RESET);   // IN1
			  HAL_GPIO_WritePin(GPIOA, GPIO_PIN_2, GPIO_PIN_RESET);   // IN2
			  HAL_GPIO_WritePin(GPIOA, GPIO_PIN_3, GPIO_PIN_SET);   // IN3
			  HAL_GPIO_WritePin(GPIOA, GPIO_PIN_4, GPIO_PIN_SET);   // IN4
			  break;

		case 6:
			  HAL_GPIO_WritePin(GPIOA, GPIO_PIN_1, GPIO_PIN_RESET);   // IN1
			  HAL_GPIO_WritePin(GPIOA, GPIO_PIN_2, GPIO_PIN_RESET);   // IN2
			  HAL_GPIO_WritePin(GPIOA, GPIO_PIN_3, GPIO_PIN_RESET);   // IN3
			  HAL_GPIO_WritePin(GPIOA, GPIO_PIN_4, GPIO_PIN_SET);   // IN4
			  break;

		case 7:
			  HAL_GPIO_WritePin(GPIOA, GPIO_PIN_1, GPIO_PIN_SET);   // IN1
			  HAL_GPIO_WritePin(GPIOA, GPIO_PIN_2, GPIO_PIN_RESET);   // IN2
			  HAL_GPIO_WritePin(GPIOA, GPIO_PIN_3, GPIO_PIN_RESET);   // IN3
			  HAL_GPIO_WritePin(GPIOA, GPIO_PIN_4, GPIO_PIN_SET);   // IN4
			  break;

		}
}

Above is the function for the Half Drive. The stepper takes 8 steps to complete 1 sequence in half drive.

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void stepper_step_angle (float angle, int direction, int rpm)
{
	float anglepersequence = 0.703125;  // 360 = 512 sequences
	int numberofsequences = (int) (angle/anglepersequence);

	for (int seq=0; seq<numberofsequences; seq++)
	{
		if (direction == 0)  // for clockwise
		{
			for (int step=7; step>=0; step--)
			{
				stepper_half_drive(step);
				stepper_set_rpm(rpm);
			}

		}

		else if (direction == 1)  // for anti-clockwise
		{
			for (int step=0; step<8; step++)
			{
				stepper_half_drive(step);
				stepper_set_rpm(rpm);
			}
		}
	}
}

The function to move the stepper by some angle. Here we can also control the direction and RPM.

Basically, the motor takes 512 sequences to complete 1 revolution. That means 512 sequences for 360 degrees. This converts to 0.703125 degrees per sequence. Using this, we can calculate the sequences required for the particular angle.

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Result