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Table des matières

2D et 3D PRIMITIVES
Contrôle de puissance

2D et 3D PRIMITIVES

Cercle, carré, rectangle, sphère, cylindre, tore, cone, …

PWM logiciel

https://github.com/sarfata/pi-blaster/ (Richard Hirst who wrote the original code recommended not going below 2us for SAMPLE_US.)
https://github.com/richardghirst/PiBits/tree/master/ServoBlaster
http://pythonhosted.org/RPIO/pwm_py.html (RPIO.PWM provides PWM via DMA for the Raspberry Pi, using the onboard PWM module for semi-hardware pulse width modulation with a precision of up to 1µs.)
http://wiringpi.com/ : GPIO Interface library for the Raspberry Pi
pwm kernel module : https://learn.adafruit.com/adafruit-raspberry-pi-lesson-9-controlling-a-dc-motor/the-pwm-kernel-module
http://raspi.tv/2013/how-to-use-soft-pwm-in-rpi-gpio-pt-2-led-dimming-and-motor-speed-control
http://hertaville.com/2014/07/07/rpipwm/

<blockquote>RPIO.PWM provides PWM via DMA for the Raspberry Pi, using the onboard PWM module for semi-hardware pulse width modulation with a precision of up to 1µs. With RPIO.PWM you can use any of the 15 DMA channels and any number of GPIOs per channel. Since the PWM is done via DMA, RPIO.PWM uses almost zero CPU resources and can generate stable pulses with a very high resolution. RPIO.PWM is implemented in C (source); you can use it in Python via the provided wrapper, as well as directly from your C source.</blockquote>

Using PWM in RPi.GPIO
 
To create a PWM instance:
 
p = GPIO.PWM(channel, frequency)
 
To start PWM:
 
p.start(dc)   # where dc is the duty cycle (0.0 <= dc <= 100.0)
 
To change the frequency:
 
p.ChangeFrequency(freq)   # where freq is the new frequency in Hz
 
To change the duty cycle:
 
p.ChangeDutyCycle(dc)  # where 0.0 <= dc <= 100.0
 
To stop PWM:
 
p.stop()
 
Note that PWM will also stop if the instance variable 'p' goes out of scope.
 
An example to blink an LED once every two seconds:
 
import RPi.GPIO as GPIO
GPIO.setmode(GPIO.BOARD)
GPIO.setup(12, GPIO.OUT)
 
p = GPIO.PWM(12, 0.5)
p.start(1)
input('Press return to stop:')   # use raw_input for Python 2
p.stop()
GPIO.cleanup()
 
An example to brighten/dim an LED:
 
import time
import RPi.GPIO as GPIO
GPIO.setmode(GPIO.BOARD)
GPIO.setup(12, GPIO.OUT)
 
p = GPIO.PWM(12, 50)  # channel=12 frequency=50Hz
p.start(0)
try:
    while 1:
        for dc in range(0, 101, 5):
            p.ChangeDutyCycle(dc)
            time.sleep(0.1)
        for dc in range(100, -1, -5):
            p.ChangeDutyCycle(dc)
            time.sleep(0.1)
except KeyboardInterrupt:
    pass
p.stop()
GPIO.cleanup()

PWM matériel

http://www.adafruit.com/products/815 : driver PWM en I2C, max 1.6KHz
Utiliser une Arduino ou une Teensy

Pulse Width Generator

Contrôle de puissance

<blockquote>Any 5V LOGIC input can be driven from 3V3. The logic HIGH is defined as 2.7V which voltage can be reached with 5V or 3V3. It is the main reason why 3V3 is so commonly used: It is the lowest supply voltage you can have and still interface with 'old' 5V logic. In telephones and other mobile equipment you see more and more 1V8 as new I/O voltage.</blockquote>