breath

Let your LEDs breathe

About

Using TinyGo on microcontroller targets, you can use PWM to fade your LEDs. This package lets you configure different "breathing" patterns such as Triangular, Circular, and Gaussian. This package is inspired by this blog post.

Usage

First, set up your desired PWM peripheral.

p := machine.PWM0
p.Configure(machine.PWMConfig{})

Next, call New to turn your LED into a Breather. Pass your desired pin along with the PWM peripheral you just created.

led := breath.New(machine.LED, p)

At this point, your LED is not breathing, but it is ready to receive a breath.Conf via the Breathe method, which passes a breath.Conf to a long-lived goroutine to which you can modify behavior as the situation changes by calling Breathe again with a new breath.Conf.

If you want to create multiple breath configurations, you can easily pass them by name. Let's create some.

bouncy := breath.Conf{
	Pattern:   breath.Circular,
	Smoothing: 750,
	Delay:     1 * time.Millisecond,
}

relaxy := breath.Conf{
	Pattern:   breath.Gaussian, // which wave to use
	Smoothing: 1024, // number of steps in wave
	Delay:     1 * time.Millisecond, // duration per step
	Beta:      0.5, // boring input to the gaussian function
	Gamma:     0.21, // exciting input to the gaussian function
}

hold := breath.Conf{
	Pattern: breath.Hold,
}

stop := breath.Conf{
	Pattern: breath.Stop,
}

We're ready to start breathing. The first time you call Breathe, a goroutine is spawned, which is intended to be a good citizen by calling the garbage collector & scheduler at appropriate times. Let's start your Breather:

led.Breathe(relaxy)

You can make the breather 'hold' its breath without exiting the goroutine by passing Pattern: Hold in a call to Breathe. The led will remain paused at the current PWM value, and a subsequent call with an active pattern will resume where the breathing left off.

led.Breathe(hold)

The breather can be stopped completely by passing a breath.Conf with a Pattern: Stop in a subsequent call to Breathe. This will cause the goroutine to exit and will bring the attached pin low.

led.Breathe(stop)

The breather is still around even though the goroutine has stopped. To start it again, merely call Breathe again with a new configuration. The same breather will spawn a new goroutine, the old one having cleaned up its resources. And yes, you can change the config on the fly without holding or stopping.

led.Breathe(bouncy)
time.Sleep(5 * time.Second)
led.Breathe(relaxy)

If you ever get curious about the current breath.Conf, you can call Conf, which is the only other method in the API. Conf will return the currently loaded values for your breather.

if led.Conf().Pattern != breath.Stop {
	led.Breathe(stop)
}