pwm-servo.py
The hobby servo sweeps 0 to 180° and back, driven at 50 Hz PWM by machine.PWM. The angle() helper converts degrees into a 0.5 to 2.5 ms pulse through duty_u16, the standard technique with no dedicated library.
Hardware
A generic RP2040 (dual Cortex-M0+) board programmed with MicroPython. 1 hobby servo (SG90 class, 3 wires: signal, +, -); external supply advised beyond a micro servo.
Wiring
Signal wire (orange) to GP16, + (red) to 5 V or external 5 V supply, - (brown) to common GND.
How it works
PWM(Pin) generates a 50 Hz square wave (20 ms period). duty_u16 sets the proportional pulse width: 0.5 ms = 0°, 1.5 ms = 90°, 2.5 ms = 180°.
Running it
Flash MicroPython via BOOTSEL (.uf2 file), then copy the script to the board drive. Check your board's user LED pin (often GP25) and adapt if needed.
Variants
Drive the angle with a potentiometer on the ADC (GP26) for a follower arm, or store positions in an angle table.
pwm-servo.py
# Balayage 0-180 degres d'un servo d'angle avec machine.PWM.
from machine import Pin, PWM
import time
SERVO_PIN = 16
servo = PWM(Pin(SERVO_PIN))
servo.freq(50) # periode 20 ms : standard des servos
def angle(a):
# 0 degre = impulsion 0,5 ms ; 180 degres = 2,5 ms.
# duty_u16 : 65535 = 100 % de la periode de 20 ms.
ms = 0.5 + (a / 180.0) * 2.0
servo.duty_u16(int(ms / 20.0 * 65535))
print("Balayage servo 0-180")
while True:
for a in range(0, 181, 5):
angle(a)
time.sleep_ms(30)
for a in range(180, -1, -5):
angle(a)
time.sleep_ms(30)
# Alimentation : pour un gros servo, utiliser une source 5 V
# externe en reliant les masses (GND commun avec la carte).