Struct Pwm 

pub struct Pwm { /* private fields */ }

A channel’s PWM setting: when in the period it turns on and when it turns off.

The PCA9685 counts from 0 to 4095 each period and lets a channel turn on at one count and off at another, so duty and phase are both programmable. The special full-on and full-off states are encoded in a dedicated bit rather than as counts.

Examples

use pamoja_actuators::pca9685::Pwm;

// Half brightness with no phase delay: on at count 0, off at the midpoint.
let half = Pwm::duty(2048);
assert_eq!(half.bytes(), [0x00, 0x00, 0x00, 0x08]);

// Fully off is its own encoding, not a zero duty.
assert_eq!(Pwm::full_off().bytes(), [0x00, 0x00, 0x00, 0x10]);

Implementations

impl Pwm

pub fn from_counts(on: u16, off: u16) -> Pwm

Builds a setting from explicit on and off counts.

Arguments

• on - the count at which the output goes high, 0..=4095.
• off - the count at which it goes low, 0..=4095.

Returns

The PWM setting; counts are masked to 12 bits.

pub fn duty(off: u16) -> Pwm

Builds a setting with no phase delay: on at count 0, off at off.

Arguments

• off - the count at which the output goes low, which sets the duty cycle.

Returns

The PWM setting.

pub fn servo(pulse_micros: u32, update_rate_hz: u32) -> Pwm

Builds the setting that drives a hobby servo to a given pulse width.

A servo reads the high-pulse width each period; the count is that width as a fraction of the period, pulse * 4096 / period. Typical travel is about 1000 to 2000 microseconds at a 50 Hz update rate.

Arguments

• pulse_micros - the high-pulse width in microseconds.
• update_rate_hz - the PWM frequency the controller is set to.

Returns

The PWM setting for that pulse width.

pub fn full_on() -> Pwm

The setting that holds the output continuously high.

Returns

The full-on setting.

pub fn full_off() -> Pwm

The setting that holds the output continuously low.

Returns

The full-off setting, the power-on state of every channel.

pub fn bytes(self) -> [u8; 4]

Returns the four register bytes for this setting.

The order is on-low, on-high, off-low, off-high, matching the channel’s four consecutive registers; the full-on and full-off flags ride in bit 4 of the high bytes.

Returns

[on_low, on_high, off_low, off_high].

pub fn from_bytes(bytes: &[u8; 4]) -> Pwm

Reads a setting back from the four register bytes a channel holds.

The inverse of bytes, so a caller can read a channel back off the bus and see what it is set to rather than decoding the registers by hand.

Arguments

• bytes - the four channel registers, [on_low, on_high, off_low, off_high].

Returns

The PWM setting those registers hold, full-on and full-off flags included.

pub fn on(self) -> u16

Returns the count at which the output goes high.

Returns

The on count, including the full-on flag in bit 12 when the output is held high.

pub fn off(self) -> u16

Returns the count at which the output goes low.

Returns

The off count, including the full-off flag in bit 12 when the output is held low.

Trait Implementations

impl Clone for Pwm

fn clone(&self) -> Pwm

Returns a duplicate of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl Copy for Pwm

impl Debug for Pwm

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl Eq for Pwm

impl PartialEq for Pwm

fn eq(&self, other: &Pwm) -> bool

Tests for self and other values to be equal, and is used by ==.

fn ne(&self, other: &Rhs) -> bool

Tests for !=. The default implementation is almost always sufficient, and should not be overridden without very good reason.

impl StructuralPartialEq for Pwm