import time
import machine
import ssd1306

# Define the OLED screen dimensions
SCREEN_WIDTH = 128
SCREEN_HEIGHT = 64

# Define the I2C bus (simulating ESP32 GPIO 21 as SDA and GPIO 22 as SCL)
i2c = machine.I2C(scl=machine.Pin(5), sda=machine.Pin(4))
oled = ssd1306.SSD1306_I2C(SCREEN_WIDTH, SCREEN_HEIGHT, i2c)

# Define the magnetic sensor input pin (simulating ESP32 GPIO 23)
magnetic_sensor_pin = machine.Pin(23, machine.Pin.IN)

# Constants for the number of magnetic pulses per revolution
PULSES_PER_REVOLUTION = 20

# Function to calculate the motor speed
def calculate_motor_speed(pulses, time_interval):
    # Calculate the number of revolutions per second
    revolutions_per_second = pulses / PULSES_PER_REVOLUTION / time_interval
    # Calculate the motor speed in RPM (Revolutions Per Minute)
    motor_speed_rpm = revolutions_per_second * 60
    return motor_speed_rpm

# Function to display text on the OLED
def display_text(text):
    oled.fill(0)  # Clear the screen
    oled.text(text, 0, 0)  # Write the text at (0, 0)
    oled.show()  # Update the display

# Main loop to continuously measure and display the motor speed
def main():
    prev_pulse_count = 0
    time_interval = 1  # Time interval in seconds

    while True:
        # Measure the pulse count at the start of the interval
        start_pulse_count = magnetic_sensor_pin.value()
        # Wait for the measurement interval
        time.sleep(time_interval)
        # Measure the pulse count at the end of the interval
        end_pulse_count = magnetic_sensor_pin.value()

        # Calculate the number of pulses occurred during the interval
        pulses = end_pulse_count - start_pulse_count

        # Calculate the motor speed
        motor_speed_rpm = calculate_motor_speed(pulses, time_interval)

        # Display the motor speed on the OLED
        display_text("Speed (RPM): {:.2f}".format(motor_speed_rpm))

if __name__ == "__main__":
    main()