In this Blog entry I will demonstrate how to access the single hardware pulse width modulation (PWM) channel available on the Raspberry Pi. The BCM2835 SOC on the Raspberry Pi has two PWM peripherals; PWM1 & PWM2. Only the PWM1 peripheral can be mapped onto a GPIO pin (GPIO18) available on the RPi’s 26-pin header. It’s important to note that both the PWM1 & PWM2 peripherals are used by Raspbian to generate audio, so make sure that the RPI is not generating audio while accessing the PWM peripherals. Since Raspbian/ Linux already assigns the PWM peripherals for audio generation, there’s strictly no direct ‘proper’ way to access the PWM1 peripheral from userspace without accessing the hardware registers directly by ‘mmaping into /dev/mem’.
Each Friday is PiDay here at Adafruit! Be sure to check out our posts, tutorials and new Raspberry Pi related products. Adafruit has the largest and best selection of Raspberry Pi accessories and all the code & tutorials to get you up and running in no time!
Make a robot friend with Adafruit’s CRICKIT – A Creative Robotics & Interactive Construction Kit. It’s an add-on to our popular Circuit Playground Express, FEATHER and other platforms to make and program robots with CircuitPython, MakeCode, and Arduino. Start controlling motors, servos, solenoids. You also get signal pins, capacitive touch sensors, a NeoPixel driver and amplified speaker output. It complements & extends your boards so you can still use all the goodies on the microcontroller, now you have a robotics playground as well.