Linux 在 sysfs 中启用 pca9685

Question

I would like to enable a PCA9685 as a PWM in /sys/class/pwm/ .

The Platform is a Raspberry Pi 2 and the chip is connected to /dev/i2c-1 .

I find the chip with i2c-detect , but i don't know how do I enable this driver: http://lxr.free-electrons.com/source/drivers/pwm/pwm-pca9685.c . I also found this but it doesn't tell me how to configure sysfs to use this driver: https://www.kernel.org/doc/Documentation/pwm.txt .

Answer 1

You need to enable CONFIG_PWM_PCA9685 in your .config file of your linux-kernel . By default, CONFIG_PWM_PCA9685 is not set and you need to enable it as CONFIG_PWM_PCA9685=y if you want to build it as a part of kernel image, or as CONFIG_PWM_PCA9685=m if you want to build it as a LKM .

Also make sure that CONFIG_SYSFS is enabled in your .config . If CONFIG_SYSFS is enabled in your kernel configuration, a simple sysfs interface is provided to use the PWMs from userspace. It is exposed at /sys/class/pwm/ . Each probed PWM controller/chip will be exported as pwmchipN , where N is the base of the PWM chip .