Introduction to the PWM pulse width modulation function of Raspberry Pi

Recently want to use Raspberry Pi control model of the ESC, so studied the next PWM, seemingly control the ESC is troublesome, because the ESC needs to send a few specific signals to start, and then to enter the control mode, today first understand PWM, slowly toss. The following program pro-test is available, I use the Raspberry Pi model B,12gpio port is the 6th pin outside.
Pulse width modulation (PWM) refers to the digital output of the microprocessor to control the analog circuit, is a digital coding method of analog signal level. On the Raspberry Pi, the PWM can be implemented by programming the GPIO.

Create a PWM instance:

GPIO. PWM (channel, frequency)

Enable PWM:

P.start (DC)   # DC represents duty-free (range: 0.0 <= DC >= 100.0)

Change frequency:

P.changefrequency (Freq)   # freq is the new frequency set, in Hz

Change duty Duty:

P.changedutycycle (DC)  # Range: 0.0 <= DC >= 100.0

Stop PWM:

P.stop ()

Note that if the variable "P" in the instance goes out of range, it can also cause a PWM stop.

The following is an example that causes the LEDs to blink once every two seconds:

Importrpi.gpio as Gpiogpio.setmode (GPIO. BOARD) Gpio.setup (GPIO). Out)  P =gpio. PWM (0.5) P.start (1) Input (' Click enter Stop: ')   # in Python 2 you need to use Raw_inputp.stop () Gpio.cleanup ()

The following is an example of switching LEDs between light and dark:

Import Timeimport Rpi.gpio as Gpiogpio.setmode (GPIO. BOARD) Gpio.setup (one, GPIO). Out) Gpio.setup (GPIO). Out) p = GPIO. PWM (P11) = GPIO. PWM (one, P.start) (0) p11.start (0) Try: While    1:        for DC in range (0, 101, 5):            p.changedutycycle (DC)            P11. Changedutycycle (DC)            Time.sleep (0.1) for        DC in range (1,-5):            p.changedutycycle (DC)            P11. Changedutycycle (DC)            Time.sleep (0.1) except Keyboardinterrupt:    passp11.stop () Gpio.cleanup ()

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Introduction to the PWM pulse width modulation function of Raspberry Pi