This is a code sample for using the sysfs interface to "breathe" an
LED using a pulsed-width modulation (PWM) signal, written in Rust. It can
be run using the standard Rust $ cargo run command or cross-compiled for
the aarch64 architecture.
This code was tested on an Odroid-C4, using the following OS: ubuntu-20.04-4.9-mate-odroid-c4-hc4-20201020.img.xz which is available here.
After flashing this image, and logging in as root (default pwd: odroid), run
$ sudo apt-get update && sudo apt-get upgrade && sudo reboot
After this, you will likely need to edit the /media/boot/config.ini file to
have the line overlays="spi0 i2c0 i2c1 uart0 pwm_ab pwm_cd pwm_ef and restart
again in order to actually have access to all 6 PWM pins. From there, the pin mapping
should be:
Pin #35 -> pwmchip0, channel 1
Pin #33 -> pwmchip0, channel 0
Pin #11 -> pwmchip4, channel 1
Pin #7 -> pwmchip4, channel 0
Pin #15 -> pwmchip8, channel 1
Pin #12 -> pwmchip8, channel 0
For those interested, a discussion thread (thanks to those who helped!) is available at https://forum.odroid.com/viewtopic.php?f=207&t=41185&sid=44d7c94d217493a781dac31b04867346