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: BCM2836/2837 quad-core, alimentation micro-USB 5 V/1,2 A, pas de Wi-Fi intégré; power servos separately beyond two.
Hardware
A Raspberry Pi 2 Model B (quad-core BCM2836/2837 SoC, 40-pin GPIO header, 100 Mbit/s Ethernet, micro-USB power). 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. The 40-pin pinout is documented on the official Raspberry Pi site.
Variants
Use gpiozero Servo(angle) for a degree API; two servos make an XY tracker. Older quad-core without Wi-Fi: prefer Ethernet; a 5 V/1.2 A micro-USB supply is recommended.
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")