Lily∞Bot With Raspberry PI Pico W: Obstacle Avoidance With 3.3V Sonar Sensor

I updated the open-source robot, Lily∞Bot to work with the Raspberry PI Pico W programmed in MicroPython.

Supplies

Lily∞Bot robot from NoireSTEMinist.com/shop
Or build the Lily∞Bot using the CAD and 3d printer files on Github at https://github.com/berry123/Lily-Bot
Microcontroller should be a Raspberry PI Pico W
Need one LED with 220 ohm resistor
One HC-SR04 3.3V sonar sensor

Step 1: Wire Up the Circuit

The figures below the text indicate how to connect circuit elements using the nodes on the breadboard, the pinout for the Raspberry Pi Pico W and the Fritizing schematic for this circuit.
Use the following steps to wire the TB6612 motor driver, sonar and LED to the Raspberry PI Pico W
Put the TB6612 motor driver in one end of the breadboard with the USB connection at the end near the end of the breadboard.
Connect the left motor to motor A (red, blk) on the TB6612
Connect the right motor to motor B (red, blk) on the TB6612
Use two wires to connect VCC and VM on the TB6612 to VBUS on the Raspberry PI Pico W. One option is to put VBUS on a row of the breadboard and use wires to connect there.
Use a wire to connect PWMA on the TB6612 motor controller to pin 28 on Raspberry PI Pico W
Use a wire to connect AIN2 on the TB6612 motor controller to pin 27 on Raspberry PI Pico W
Use a wire to connect AIN1 on the TB6612 motor controller to pin 26 on Raspberry PI Pico W
Use a wire to connect BIN1 on the TB6612 motor controller to pin 22 on Raspberry PI Pico W
Use a wire to connect BIN2 on the TB6612 motor controller to pin 21 on Raspberry PI Pico W
Use a wire to connect PWMB on the TB6612 motor controller to pin 20 on Raspberry PI Pico W
Use these steps to wire up the LED and sonar circuit before writing the program.
The following first two circuits show the nodes for meeting points on a breadboard and the Raspberry PI Pico W wiring diagram
Put the 220 ohm resistor on the breadboard with each leg in a different row.
Put the LED in the breadboard with the short leg on the same row as the 220 ohm resistor
Put the long leg of the LED on a different row and connect the long leg of the LED to pin 18
Use a wire to connect the other leg of the 220 ohm resistor to ground.
Use the sonar mount to connect the sonar to the front of Lily∞Bot.
Use a wire to connect the VCC pin on the sonar to the 3.3 V (OUT) pin on the Raspberry PI Pico W. This pin is 5th from the top on the right
Use a wire to connect the GND pin on the sonar to any ground pin on the Raspberry PI Pico W.
Use a wire to connect the TRIG pin on the sonar to pin 17 on the Raspberry PI Pico W.
Use a wire to connect the ECHO pin on the sonar to pin 16 on the Raspberry PI Pico W.

Step 2: Write the Code

Open up PlatformIO Visual Studio and create a.py file
Configure the file as a MicroPico project
Copy the file code into the file and then save.
Right click on the file name and select "Run current file on Pico"

#obstacleAvoicance.py CAB 9.17.23
#This code will drive the LilyBot forward
#then turn when obstacle is detected with sonar
#https://www.noiresteminist.com/shop


#Carlotta Berry 9.14.23


from machine import Pin, ADC, PWM
from utime import ticks_us, sleep_us, sleep_ms


#define inputs and outputs
ledPin = 18
triggerPin = 17
echoPin = 16
trigger = Pin(triggerPin, Pin.OUT)
echo = Pin(echoPin, Pin.IN)
led = Pin(ledPin, Pin.OUT)
pin = Pin("LED", Pin.OUT)

#define inputs and outputs
PWMA = PWM(Pin(28))
AIN2 = Pin(27, Pin.OUT)
AIN1 = Pin(26, Pin.OUT)
PWMA.freq(60)


BIN1 = Pin(22, Pin.OUT)
BIN2 = Pin(21, Pin.OUT)
PWMB = PWM(Pin(20))
PWMB.freq(60)
motorSpeed = 65535


def reverse():
    AIN1.value(1)
    AIN2.value(0)
    BIN1.value(1)
    BIN2.value(0)
    PWMA.duty_u16(motorSpeed)
    PWMB.duty_u16(motorSpeed)


def forward():
    AIN1.value(0)
    AIN2.value(1)
    BIN1.value(0)
    BIN2.value(1)
    PWMA.duty_u16(motorSpeed)
    PWMB.duty_u16(motorSpeed)


def pivot():
    AIN1.value(0)
    AIN2.value(0)
    BIN1.value(0)
    BIN2.value(1)
    PWMA.duty_u16(motorSpeed)
    PWMB.duty_u16(motorSpeed)


def stop():
    AIN1.value(0)
    AIN2.value(0)
    BIN1.value(0)
    BIN2.value(0)


def distance():
    timepassed=0
    signalon = 0
    signaloff = 0
    trigger.low()
    sleep_us(2)
    trigger.high()
    sleep_us(5)
    trigger.low()
    while echo.value() == 0:
        signaloff = ticks_us()
    while echo.value() == 1:
        signalon = ticks_us()
    #print(signalon)
    #print(signaloff)
    timepassed = signalon - signaloff
    #print(timepassed)
    dist_cm = (timepassed*0.0343)/2
    if dist_cm>60:
        dist_cm=60
    return dist_cm


print("Obstacle Avoidance on Lily∞Bot...")


while True:
    reading = distance()
    print(reading)


    if reading<10:
        led.value(1)
        stop()
        sleep_ms(100)
        reverse()
        sleep_ms(500)
        pivot()
        sleep_ms(500)
        reading = distance()
    else:
        led.value(0)
        forward()
        sleep_ms(100)
        reading = distance()