servo_sweep.py
An SG90-class servo is driven with 50 Hz PWM on GPIO18 (pin 12) via gpiozero PWMOutputDevice: value=0 means 0 degrees, value=1 means 180. The script sweeps continuously. Mind the power budget: format compact, Wi-Fi 2,4/5 GHz, alimentation USB-C 5 V/2,5 A; power servos separately beyond two.
Hardware
A Raspberry Pi 3 Model A+ (compact format, BCM2837B0, 5 GHz Wi-Fi + Bluetooth, a single USB port, 5 V/700 mA power, 40-pin GPIO). One SG90 micro-servo (or similar), an external 5 V supply recommended, dupont wires.
Wiring
Orange/yellow signal wire to GPIO18 (pin 12), brown/red to 5 V, black/yellow to GND shared with the board.
How it works
PWMOutputDevice emits a 50 Hz pulse train, 0.5–2.5 ms wide; the servo angles its horn with the pulse width.
Running it
Copy the script to the board (scp), then run it with python3 (or bash). Raspberry Pi OS ships gpiozero; otherwise sudo apt install python3-gpiozero. Mind the 700 mA power budget for USB peripherals.
Variants
Use gpiozero Servo(angle) for a degree API; two servos make an XY tracker. Compact board to cool; USB-C 5 V/2.5 A; a single USB port, add a hub if needed.
servo_sweep.py
# servo_sweep.py — balaie un micro-servo (SG90) de 0 a 180 degres.
# Deps: sudo apt install python3-gpiozero
from gpiozero import PWMOutputDevice
from time import sleep
servo = PWMOutputDevice(18, frequency=50, pulse_width=0.001)
print("Balayage servo, Ctrl+C pour sortir")
try:
while True:
for deg in range(0, 181, 15):
servo.value = deg / 180.0
sleep(0.05)
for deg in range(180, -1, -15):
servo.value = deg / 180.0
sleep(0.05)
except KeyboardInterrupt:
servo.off()
print("Arret")