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Getting Started With the RPI Pico W

During college, I had the chance to work with a few different microcontrollers, which was around the same time that I discovered my passion for coding. While working as a Teaching Fellow for an electronics class, I was able to experiment with an Arduino Uno and found it to be an enjoyable experience. As I started to comprehend the capabilities and potential uses of this amazing little machine, I registered for an elective course that introduced me to the ESP32. This microcontroller was even more powerful, featuring built-in Bluetooth and WiFi, allowing me to perform some very impressive tasks. However, the ESP32 was incredibly unreliable, forcing me to purchase a second board. It was during this same period that the Raspberry Pi Foundation released the Pico W, another small computer with built-in wireless connectivity, much like the ESP32. Not only was the Pico W much more reliable, but it was also more affordable and cuter, so I knew I had to get one.

Here's a very quick Getting Started Guide with the Pico W and Thonny (IDE)

Download the correct MicroPython UF2 file for your board *here*
Plug the board in, holding down the BOOTSEL button, drag and drop the UF2 file
Plug it back in and open Thonny
Select the interpreter in the bottom right

thonny_interpreter

Type in the shell the following: print(“hello world”)

You should be good to go!

Your First Project

The "Hello World" of microcontrollers: blinking an LED

In Thonny, type:

                # Pin allows us to control the pins
                from machine import Pin
                
                # We need time to sleep (pause) the device
                import time
                
                # Defining a Pin object as the built in LED
                # To select a different digital pin to control, we need to specify its number
                # Uncomment the following line to control digital pin 5 (GPIO 3)
                # led = Pin(3, Pin.OUT)
                led = Pin("LED", Pin.OUT)

                
                # Infinite loop to blink LED
                while True:
                    print("Blink!")
                    led.on()
                    time.sleep(1)
                    led.off()
                    time.sleep(1)

Your LED should now be blinking

Lets try something a little harder

Reading a voltage using the ADC

Wire it up as follows

pot_wiring

In Thonny, type:

                from machine import Pin, ADC
                from time import sleep

                # Set up a potentiometer with outer pins at 3.3V and gnd,
                # and the middle pin connected to GPIO pin 26

                # ADC functionality is available on pin 26

                adc = ADC(Pin(26))     # create an ADC object 

                while True:
                    v = adc.read_u16()    # read raw value from 0 to (2^16)-1 (65535)
                    print(f'read_u16: {v}')
                    sleep(0.1)
    
                # 12-bit ADC, so read_u16() resolution is 2^4 since 2^(12+4) = 2^16

And you should get something like:

read_u16: 32920

To get a voltage, we need to do some math to this number according to the following formula

Voltage = (code*V_FSR)/(2^m)

Where:

code is what the adc.read() returns

V_FSR is the full scale range voltage (3.3V)

m is the resolution (16 bits)

You can change the print line to “print(f'read_u16: {v*3.3/(2**16)} V')” to print it as a Voltage. Keep in mind you can only read up to V_FSR. To read higher voltages, you'll need more circuitry.