Tag Archives: Raspberry Pi Pico

Bodgers – More Distance Sensors

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This week we are going to try making a measuring device using our HC-SR04 sensors.

First we’ll wire our circuit up.

Next let’s test our circuit with the following code.

from machine import Pin
import utime
from time import sleep

trigger = Pin(17, Pin.OUT)
echo = Pin(16, Pin.IN, Pin.PULL_DOWN)
buzzer = Pin(15, Pin.OUT)


def ultra():
    trigger.low()
    utime.sleep_us(2)
    trigger.high()
    utime.sleep_us(5)
    trigger.low()
    while echo.value() == 0:
        signaloff = utime.ticks_us()
    while echo.value() == 1:
        signalon = utime.ticks_us()
    timepassed = signalon - signaloff
    distance = (timepassed * 0.0343) / 2
    print("The distance from object is ", distance, "cm")
    return distance


def buzz():
    buzzer.value(1)
    sleep(0.5)
    buzzer.value(0)
    sleep(0.5)


while True:
    dist = ultra()
    if dist < 30:
        buzz()
    utime.sleep(1)

This week’s challenge is to rewrite the code so the the closer to something the sensor is the faster it will beep.

Once we have that done we will look at transferring the code onto the Pico itself and running it from a battery.

Bodgers – Servos

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This week we will connect a SG90 mini servo to our Pico.

Wire the breadboard as shown below:

First test that the buttons are working correctly with the following code.

from machine import Pin
from time import sleep

button_1 = Pin(18, Pin.IN, Pin.PULL_UP)
button_2 = Pin(19, Pin.IN, Pin.PULL_UP)

while True:
    if button_1.value() == 0:
        print("Button 1 is Pressed")
    if button_2.value() == 0:
        print("Button 2 is Pressed")
    sleep(0.1)

Next here is the code for the Servo.

from machine import Pin, PWM
from time import sleep

servo_pin = PWM(Pin(0))
servo_pin.freq(50)

def servo(degrees):
    if degrees > 180:
        degrees = 180
    if degrees < 0:
        degrees = 0
       
    max_duty = 8050
    min_duty = 1650
       
    new_duty = (min_duty + (max_duty - min_duty) * (degrees/180))
    servo_pin.duty_u16(int(new_duty))

servo(0)
sleep(0.5)
servo(90)
sleep(0.3)
servo(180)
sleep(0.3)

This weeks challenge is to combine both pieces of code above so that when button 1 is pressed the servo arm will move one way and when button 2 is pressed it will move in the opposite direction.

Bodgers – Buttons

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This week we are looking at using buttons on our Raspberry Pi Picos.

Connect the LEDs and Buttons to the Pico as shown below:

Next use the code below to test the LEDs

from machine import Pin
from time import sleep

red_led = Pin(15, Pin.OUT)
green_led = Pin(14, Pin.OUT)

def blink():
    red_led.value(1)
    sleep(0.5)
    red_led.value(0)
    green_led.value(1)
    sleep(0.5)
    green_led.value(0)

while True:
    blink()

Next we’ll test the buttons using the following code:

from machine import Pin
from time import sleep

button_1 = Pin(18, Pin.IN, Pin.PULL_UP)
button_2 = Pin(19, Pin.IN, Pin.PULL_UP)

while True:
    if button_1.value() == 0:
        print("Button 1 is Pressed")
    if button_2.value() == 0:
        print("Button 2 is Pressed")
    sleep(0.1)

This week’s challenge is create a program called buttons_leds.py that turns on the red LED and turns off the green LED when button 1 is pressed and when button 2 is pressed will turn the green one on and the red one off.

Bodgers – Distance Sensors

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This week we will be using the HC-SR04 Ultrasonic Distance Sensor

Wire up the sensor as shown below

Here is the code we will need for the sensor.

#From www.tomshardware.com/how-to/raspberry-pi-pico-ultrasonic-sensor
from machine import Pin
import utime

trigger = Pin(17, Pin.OUT)
echo = Pin(16, Pin.IN, Pin.PULL_DOWN)

def ultra():
   trigger.low()
   utime.sleep_us(2)
   trigger.high()
   utime.sleep_us(5)
   trigger.low()
   while echo.value() == 0:
       signaloff = utime.ticks_us()
   while echo.value() == 1:
       signalon = utime.ticks_us()
   timepassed = signalon - signaloff
   distance = (timepassed * 0.0343) / 2
   print("The distance from object is ",distance,"cm")

while True:
   ultra()
   utime.sleep(1)

Once this is working you can move on to this week’s challenge. Combine this with the LED code from the last session so that the LED flashes when the distance measured by the sensor is less than 30CM. Here is the LED code:

from machine import Pin
from time import sleep

led = Pin(15, Pin.OUT)

def flash():
    led.value(1)
    sleep(0.5)
    led.value(0)
    sleep(0.5)
    
while True:
    flash()