OBOCar SDK Documentation

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Introduction

The OBOCar SDK is a lightweight MicroPython library designed for controlling the OBOCar using the ESP32 microcontroller. It supports motor control, buzzer interaction, OLED display, Ultrasonic Sensors and button inputs. This guide is tailored for use with Thonny IDE.

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Features

• Motor Control:
  • Forward, backward, left, and right motion with speed control (max: 512).
• Buzzer:
  • Generate single beeps or play sequences of tones.
• OLED Display:
  • Display text messages on an SSD1306 OLED screen.
• Buttons:
  • Detect left and right button presses.
• Ultrasonic:
  • Measure distances for obstacle detection using front, left, and right sensors.

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Prerequisites

1. Install Thonny IDE:

   • Download and install Thonny IDE from Thonny.org.

2. Install MicroPython on ESP32:

   • Open Thonny IDE.
   • Go to Run -> Configure Interpreter.
   • In the "Interpreter" section, select:
     • MicroPython (ESP32) under "MicroPython family."
     • For the "Port," choose < Try to detect port Automatically >
   • Click Install or update MicroPython (esptool).
   • Choose:
     • For the "Target Port," choose the correct Target Port for your ESP32 (e.g., COM3, COM4, /dev/ttyUSB0).
     • MicroPython family: ESP32.
     • Variant: Espressif ESP32 / WROOM.
   • Click Install to flash MicroPython onto your ESP32.

3. Upload the OBOCar SDK:

   • Create a new file in Thonny.
   • Copy the contents of obocar.py into the file.
   • Click Save
   • Select 'Micropython device'
   • Rename as obocar.py
   • Select OK

4. Upload the Test Code:

   • Create a new file in Thonny.
   • Copy the contents of boot.py into the file.
   • Click Save
   • Select 'Micropython device'
   • Rename as boot.py
   • Select OK
   • Extra : If a dialogue box appeared asking overwriting click OK

Once MicroPython is installed, you can connect to the ESP32 via Thonny and start using the SDK. Continue with the usage examples and SDK features listed above!

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Troubleshooting MicroPython on ESP32

If you encounter issues such as a "Backend not ready" warning or the program seems stuck, follow these steps to reset your ESP32:

1. Press the Stop Button:

   • In Thonny, click the red Stop button located at the top to interrupt any running code.

2. Reset via Shell:

   • If pressing the stop button doesn’t resolve the issue:
     • Make sure you do not click or interact with the shell section in Thonny.
     • Instead, press Ctrl + C twice in quick succession to force a reset of the ESP32.

3. Reconnect the Device:

   • If the device still doesn't respond, unplug and replug your ESP32.
   • Go to Run -> Configure Interpreter and verify the Target Port is still correctly set.

4. Reinstall MicroPython (Optional):

   • If the problem persists, you may need to reinstall MicroPython using the instructions provided above.

With these steps, you should be able to regain control of your ESP32 and continue using the OBOCar SDK.

Setup

Hardware Connections

Component	ESP32 Pin	Details
Motor Left (L1)	GPIO 5	Motor left control 1
Motor Left (L2)	GPIO 4	Motor left control 2
Motor Right (R1)	GPIO 19	Motor right control 1
Motor Right (R2)	GPIO 18	Motor right control 2
Buzzer	GPIO 2	Sound output
OLED SCL	GPIO 22	I2C clock
OLED SDA	GPIO 21	I2C data
Button Left	GPIO 17	Detect left button press
Button Right	GPIO 16	Detect right button press
Ultrasonic Trigger Front	GPIO 32	Trigger pin for front sensor
Ultrasonic Echo Front	GPIO 39	Echo pin for front sensor
Ultrasonic Trigger Left	GPIO 13	Trigger pin for left sensor
Ultrasonic Echo Left	GPIO 15	Echo pin for left sensor
Ultrasonic Trigger Right	GPIO 23	Trigger pin for right sensor
Ultrasonic Echo Right	GPIO 36	Echo pin for right sensor

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Initialization

Initialize the OBOCar using the following example:

from obocar import OBOCar

# Initialize OBOCar
car = OBOCar()

Motor Control

car.move_forward(speed=512)  # Move forward at maximum speed
car.move_backward(speed=256)  # Move backward at half speed
car.turn_left(speed=512)  # Turn left at maximum speed
car.turn_right(speed=512)  # Turn right at maximum speed
car.stop()  # Stop the car

Buzzer

car.beep(freq=1000, duration=0.5)  # Play a 1000 Hz tone for 0.5 seconds
car.start_tone()  # Play startup tone sequence

OLED Display

car.display("Hello, OBOCar!", 0, 0)  # Display a message on the OLED

Button Interaction

if car.is_buttonL_pressed():
    print("Left button pressed!")

if car.is_buttonR_pressed():
    print("Right button pressed!")

Ultrasonic Sensors

The OBOCar SDK includes support for ultrasonic sensors for obstacle detection in three directions: front, left, and right.

# Measure the front distance
front_distance = car.get_front_distance()
print(f"Front distance: {front_distance:.2f} cm")

# Measure the left distance
left_distance = car.get_left_distance()
print(f"Left distance: {left_distance:.2f} cm")

# Measure the right distance
right_distance = car.get_right_distance()
print(f"Right distance: {right_distance:.2f} cm")

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Ultrasonic Obstacle Avoidance

The ultrasonic sensors can be used for obstacle Avoidance. Example:

# Simple obstacle avoidance

from obocar import OBOCar
import time
car = OBOCar()

while True:
    front_distance = car.get_front_distance()
    if front_distance < 20:  # If an obstacle is closer than 20 cm
        car.move_backward(512)
        time.sleep(0.3)
        car.turn_left(512)
        print("Obstacle detected! Turning...")
        time.sleep(0.5)
    else:
        car.move_forward(speed=512)
    time.sleep(0.1)

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Convert Image to byteArray

import convert.py
converted = convert.image_to_buffer(r"/Users/sanjulagathsara/Desktop/GitHub Repos/obocar/img2.png")
buffer = converted[0]
buffer

Show Image

import framebuf

roboticgen_logo = bytearray(b'\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x0f\x80\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x0f\xf8\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x07\xfc\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x078\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x03\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\xff\x80\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x0f\xff\x80\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00~\xff\xc0\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x03\xc0\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00`\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00`\x00\x00\x06\x03\x80\x00\x00\x00\x00\x00\x00\x07\xfc\x00\x00\xf0\x00\x00\x0e\x07\x80\x00\x0f\x80\x00\x00\x00\x07\xfe\x00\x00p\x00\x00\x0e\x07\x80\x00?\xe0\x00\x00\x00\x07\xff\x00\x00p\x00\x00\x0e\x03\x00\x00\x7f\xe0\x00\x00\x00\x07\x07\x80\x00`\x00\x00\x0e\x00\x00\x00\xf0`\x00\x00\x00\x07\x03\x83\xf0\x7f\xc0~\x1f\xf3\x87\xe1\xe0\x00|\x07\xc0\x07\x01\xc7\xf8\x7f\xe0\xff\x1f\xf3\x8f\xf9\xc0\x01\xff?\xe0\x07\x01\xcf\xfc\x7f\xf1\xff\x9f\xf3\x9f\xf9\xc0\x01\xef?\xf0\x07\x01\xde\x1exs\xc3\x8e\x03\x9c1\x80\x03\x8e<p\x07\x03\x9c\x0eps\x81\xce\x03\x9c\x01\x80s\x9e88\x07\x8f\x9c\xcew;\x99\xce\x03\xb8\x01\xc0s\x1c88\x07\xff\x1c\xcec3\x99\xce\x03\xb8\x01\xc0s888\x07\xfe\x1c\x0eps\x81\xce\x03\xbc\x01\xe0s\xf088\x07\xfe\x1e\x1cx\xf3\xc3\x87\x03\x9e0\xf0s\xe288\x07\x0e\x0f\xfc?\xf1\xff\x87\xf3\x9f\xf8\x7f\xf1\xff88\x07\x07\x07\xf8?\xe0\xff\x03\xf3\x8f\xf8?\xe0\xff88\x07\x07\x03\xf0\x0f\x80~\x01\xf3\x83\xe0\x1f\xc0|\x180\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00')
fb = framebuf.FrameBuffer(roboticgen_logo, 128, 33, framebuf.MONO_HLSB)
car.OLED.framebuf.blit(fb, 0, 14)
car.OLED.show()

Contribute:
Suggestions and improvements are welcome! This SDK is designed to be extensible for further development in OBOCAR.