Cytron Maker PI RP2040 - Great board for everyone, but missing two things.

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RoadTest: Sign Up to Roadtest the Cytron MAKER PI RP2040

Author: feiticeir0

Creation date: 11 Jun 2023

Evaluation Type: Development Boards & Tools

Did you receive all parts the manufacturer stated would be included in the package?: True

What other parts do you consider comparable to this product?: Raspberry PI Pico

What were the biggest problems encountered?: None.

Detailed Review:

Hi all.

Here's my take on the Cytron Maker PI RP2040. I had to place it on YouTube because there's an issue with the Element14's site regarding uploading files bigger than 50MB.

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Cytron Maker PI RP2040 - Great board for everyone, but missing two things.

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Final Project - "Autonomous" Car

To demonstrate the board, I decided to create an "Autonomous" car. Using a Ultrasonic HC-SR04 sensor to measure the distance to objects, the car would detect objects in front of it and change direction. Using a servo, it will measure distance in the left and right and decide which way to turn and go.

Here's the schematics:

Because I'm having a lot of difficulty using the SR04 ultrasonic sensor.  Sometimes it doesn't work - it's like it's not detecting the PINs or the sensor.

I get this error:

>>> %Run -c $EDITOR_CONTENT

MPY: soft reboot
Traceback (most recent call last):
  File "<stdin>", line 33, in <module>
  File "<stdin>", line 29, in ultrasound
NameError: local variable referenced before assignment
>>>

I know it's not the sensor, because I've tried several...

Even with this library,hcsr04.py, that had worked well a few times, I had problems.  So, I tried a new approach - I had a Time Of Flight sensor at home, I decide to give it a try.

I found this library - VL53L0X - that works with MicroPython. I had to discover the Raspberry PI PICO I2C PINs, because the Maker PI RP2040 doesn't specify - It's Grove 4 - GP16 and GP17.

So, I've change to a Time Of Flight Sensor.

Here's the code for the various examples and at the end the code for the final project.

Buzzer

Here's the code to test the buzzer.

Testing the buzzer

from machine import Pin, PWM
from utime import sleep

buzzer = PWM(Pin(22))

# frequency - higher the number, higher the pitch
# from 10 and 12.000
buzzer.freq(1000)

#set volume - don't really know how high this can be
buzzer.duty_u16(10000)

sleep(1)
#stop buzzer
buzzer.duty_u16(0)

Play a melody

The tones.py file is straight from the arduino examples, but change to use a dictionary in Python.

In the code are the URLs for the examples

""" Playing a Song """
# based on https://www.tomshardware.com/how-to/buzzer-music-raspberry-pi-pico
# https://www.coderdojotc.org/micropython/sound/05-play-mario/

from machine import Pin, PWM
from utime import sleep

#import notes form tones.py
from tones import tones

#declare buzzer
buzzer = PWM(Pin(22))

mario = ["E7", "E7", 0, "E7", 0, "C7", "E7", 0, "G7", 0, 0, 0, "G6", 0, 0, 0, "C7", 0, 0, "G6",
         0, 0, "E6", 0, 0, "A6", 0, "B6", 0, "AS6", "A6", 0, "G6", "E7", 0, "G7", "A7", 0, "F7", "G7",
         0, "E7", 0,"C7", "D7", "B6", 0, 0, "C7", 0, 0, "G6", 0, 0, "E6", 0, 0, "A6", 0, "B6", 0,
         "AS6", "A6", 0, "G6", "E7", 0, "G7", "A7", 0, "F7", "G7", 0, "E7", 0,"C7", "D7", "B6", 0, 0]


def playtone(frequency):
    buzzer.duty_u16(10000)
    buzzer.freq(frequency)

def bequiet():
    buzzer.duty_u16(0)

def playsong(mysong):
    for i in range(len(mysong)):
        if (mysong[i] == "P" or mysong[i] == 0):
            bequiet()
        else:
            playtone(tones[mysong[i]])
        sleep(0.2)
    bequiet()
playsong(mario)

In the first URL is the link to get the tones.py file.

DC Motors

Here's the code to testing the motors.

The class is already set for the Cytron Maker PI RP2040 pins

dcmotors.py class code

# This class defines the motors to go
from machine import Pin, PWM
class DCMotor:
    def __init__(self):
        # left Motors definitions
        self.Motor_A1 = PWM(Pin(8, Pin.OUT))
        self.Motor_A2 = PWM(Pin(9, Pin.OUT))
        # right motors definitions
        self.Motor_B1 = PWM(Pin(10, Pin.OUT))
        self.Motor_B2 = PWM(Pin(11, Pin.OUT))

        #set frequency
        self.Motor_A1.freq(50)
        self.Motor_A2.freq(50)
        self.Motor_B1.freq(50)
        self.Motor_B2.freq(50)

    # forward
    def forward(self,speed = 30000):
        print (speed)
        # right motors
        self.Motor_A1.duty_u16(speed)
        self.Motor_A2.duty_u16(0)
        # left motors
        self.Motor_B1.duty_u16(speed)
        self.Motor_B2.duty_u16(0)

    # stop
    def stop(self):
        # right motors
        self.Motor_A1.duty_u16(0)
        self.Motor_A2.duty_u16(0)
        # left motors
        self.Motor_B1.duty_u16(0)
        self.Motor_B2.duty_u16(0)

    # backward
    def backward(self, speed = 30000):
        # right motors
        self.Motor_A1.duty_u16(0)
        self.Motor_A2.duty_u16(speed)
        # left motors
        self.Motor_B1.duty_u16(0)
        self.Motor_B2.duty_u16(speed)

    # turn Right
    def turnRight(self, speed = 35000):
        # right motors
        self.Motor_A1.duty_u16(speed)
        self.Motor_A2.duty_u16(0)
        # left motors
        self.Motor_B1.duty_u16(0)
        self.Motor_B2.duty_u16(speed)

    # turn Left
    def turnLeft(self, speed = 35000):
        # right motors
        self.Motor_A1.duty_u16(0)
        self.Motor_A2.duty_u16(speed)
        # left motors
        self.Motor_B1.duty_u16(speed)
        self.Motor_B2.duty_u16(0)

The actual code of testing

from machine import Pin, PWM
from utime import sleep
from time import sleep
from dcmotor import DCMotor

motors = DCMotor()

# clockwise - A1 False | A2 True
# counterclockwise - A1 True | A2 False
# set duty cycle - speed 0 and 65535

# Forward
motors.forward (65000)

sleep(4)

#stop
motors.stop()

# turn right
motors.turnRight (45000)
sleep(1.5)

# Backward
motors.backward (40000)
sleep(2)

#stop
motors.stop()
sleep(1)

# turn left
motors.turnLeft (45000)
sleep(1.5)

# Forward
motors.forward (65000)
sleep(3)
motors.stop()

WS2812B LEDs

The code to control an external LED strip is straight from the MicroPython documentation.

Here's the code changed for the Cytron

import machine, neopixel
import time
np = neopixel.NeoPixel(machine.Pin(26), 9)

def demo(np):
    n = np.n

    # cycle
    for i in range(4 * n):
        for j in range(n):
            np[j] = (0, 0, 0)
        np[i % n] = (255, 255, 255)
        np.write()
        time.sleep_ms(25)

    # bounce
    for i in range(4 * n):
        for j in range(n):
            np[j] = (0, 0, 128)
        if (i // n) % 2 == 0:
            np[i % n] = (0, 0, 0)
        else:
            np[n - 1 - (i % n)] = (0, 0, 0)
        np.write()
        time.sleep_ms(60)

    # fade in/out
    for i in range(0, 4 * 256, 8):
        for j in range(n):
            if (i // 256) % 2 == 0:
                val = i & 0xff
            else:
                val = 255 - (i & 0xff)
            np[j] = (val, 0, 0)
        np.write()

    # clear
    for i in range(n):
        np[i] = (0, 0, 0)
    np.write()

Time Of Flight Sensor

The code for the Time Of Flight sensor example.

The library can be found here.

import time
from machine import Pin
from machine import I2C
import VL53L0X

sda=machine.Pin(16) # lower right pin
scl=machine.Pin(17) # one up from lower right pin
i2c=machine.I2C(0, sda=sda, scl=scl, freq=400000)

# Create a VL53L0X object
tof = VL53L0X.VL53L0X(i2c)

def calculate_distance():
    tof.start()
    tof.read()
    distance = tof.read()
    tof.stop()
    return distance

while True:
    """
    tof.start()
    tof.read()
    print(tof.read())
    tof.stop()
    """
    print (calculate_distance())
    time.sleep(0.1)

Robot code

After all this, here's the code used to testing the board on the robot, by avoind obstacles using the Time Of Flight sensor

import machine
import time
from machine import Pin, PWM
from time import sleep
from dcmotor import DCMotor
import VL53L0X
from lighting import Lighting


sda=machine.Pin(16) # lower right pin
scl=machine.Pin(17) # one up from lower right pin
i2c=machine.I2C(0, sda=sda, scl=scl, freq=400000)

# Create a VL53L0X object
tof = VL53L0X.VL53L0X(i2c)


# define the leds
leds = Lighting()

# Define pin for servo motor
servo_pin = Pin(15)
servo = machine.PWM(servo_pin)
servo.freq(50)
# fine tune the duty cycle values to suit your servo motor
MIN_DUTY = 2000
MAX_DUTY = 5100

# Motors
motors = DCMotor()

def calculateAngle(angle):
    return int(((MAX_DUTY - MIN_DUTY) / 180) * angle) + MIN_DUTY

""" Calculate distance using the TOF sensor """
""" Returns distance in mm """
def calculate_distance():
    tof.start()
    tof.read()
    distance = tof.read()
    tof.stop()
    return distance

# Function to move robot based on distance measurements
def move_robot():
    distance = calculate_distance()
    print (distance)

    if distance > 90:  # If no obstacle in front
        servo.duty_u16(calculateAngle(90))  # Set servo to center position
        # Move robot forward
        motors.forward()
        time.sleep(2)
        motors.stop()

    else:  # If obstacle detected
        servo.duty_u16(calculateAngle(45))  # Set servo to left position
        time.sleep(0.5)
        distance_left = calculate_distance()

        servo.duty_u16(calculateAngle(135))  # Set servo to right position
        time.sleep(0.5)
        distance_right = calculate_distance()

        if distance_left > distance_right:
            # back a bit
            motors.backward()
            time.sleep(0.7)
            # Move robot left
            motors.turnLeft()
            time.sleep(1)
        else:
            # back a bit
            motors.backward()
            time.sleep(0.7)
            # Move robot right
            motors.turnRight()
            time.sleep(1)


# First, set servo to 90 degrees
servo.duty_u16(calculateAngle(90))

# Main loop
while True:
    move_robot()
    time.sleep(0.1)

Files

All the files used are attached .

Here's the URLs for the libraries used:

https://www.tomshardware.com/how-to/buzzer-music-raspberry-pi-pico
https://www.coderdojotc.org/micropython/sound/05-play-mario/

VL53L0X is from github - several repositories have it, just search

Conclusion

Overall, I'm really impressed with the Cytron Maker Pi RP2040.

It's a powerful and versatile board that's packed with features and components, making it a great choice for anyone looking to build a robot or other project.

The automatic power selection and built-in LiPo/Li-Ion charger are especially convenient, and the preloaded CircuitPython makes it easy to get started with programming right out of the box. Whether you're a beginner or an experienced maker, the Cytron Maker Pi RP2040 is definitely worth considering for your next project.

Missing something

Don't get me wrong, this board is really great. But I would love to see some exposed GPIO Pins so I don't have to use a grove connector . Like they have done with the servo PINs, place like 3 or 4 exposed ones to use.

WiFi. They should think about that in a future revision of the board. I

References / Music

Music by FASSounds from Pixabay

Music by FASSounds from Pixabay

Music by Lofi_hour from Pixabay

Music by Lofium from Pixabay

Music by BrentinDavis from Pixabay

Music by BrentinDavis from Pixabay