Pca9685PwmAdapter Class Reference

BasePwm adapter for all 16 PCA9685 PWM channels. More...

#include <Pca9685Handler.h>

Inheritance diagram for Pca9685PwmAdapter:

Collaboration diagram for Pca9685PwmAdapter:

Public Member Functions
	Pca9685PwmAdapter (Pca9685Handler *parent_handler) noexcept
	Construct the PWM adapter.
	~Pca9685PwmAdapter () noexcept override=default
	Default destructor.
BasePwm Interface Implementation
hf_pwm_err_t	Initialize () noexcept override
	Initialize the PWM adapter (ensures parent handler is initialized).
hf_pwm_err_t	Deinitialize () noexcept override
	Deinitialize (marks adapter as uninitialized).
hf_pwm_err_t	EnableChannel (hf_channel_id_t channel_id) noexcept override
	Enable a PWM channel (restore its duty cycle from cache).
hf_pwm_err_t	DisableChannel (hf_channel_id_t channel_id) noexcept override
	Disable a PWM channel (set to full-off).
bool	IsChannelEnabled (hf_channel_id_t channel_id) const noexcept override
	Check if a channel is enabled.
hf_pwm_err_t	SetDutyCycle (hf_channel_id_t channel_id, float duty_cycle) noexcept override
	Set duty cycle for a channel (0.0-1.0).
hf_pwm_err_t	SetDutyCycleRaw (hf_channel_id_t channel_id, hf_u32_t raw_value) noexcept override
	Set raw PWM tick value for a channel.
hf_pwm_err_t	SetFrequency (hf_channel_id_t channel_id, hf_frequency_hz_t frequency_hz) noexcept override
	Set PWM frequency (global – affects ALL channels).
hf_pwm_err_t	SetPhaseShift (hf_channel_id_t channel_id, float phase_shift_degrees) noexcept override
	Set phase shift for a channel (via PCA9685 on-time offset).
hf_pwm_err_t	StartAll () noexcept override
	Wake the PCA9685 from sleep (start all channels).
hf_pwm_err_t	StopAll () noexcept override
	Put the PCA9685 into sleep mode (stop all outputs).
hf_pwm_err_t	UpdateAll () noexcept override
	No-op (PCA9685 updates immediately on register write).
hf_pwm_err_t	SetComplementaryOutput (hf_channel_id_t primary_channel, hf_channel_id_t complementary_channel, hf_u32_t deadtime_ns) noexcept override
	Not supported by PCA9685.
float	GetDutyCycle (hf_channel_id_t channel_id) const noexcept override
	Get the cached duty cycle for a channel.
hf_frequency_hz_t	GetFrequency (hf_channel_id_t channel_id) const noexcept override
	Get the current PWM frequency (global).

Static Public Attributes
static constexpr uint8_t	kMaxChannels = 16
	Number of PWM channels on the PCA9685.
static constexpr uint8_t	kResolutionBits = 12
	PWM resolution in bits.
static constexpr uint16_t	kMaxRawValue = 4095
	Maximum raw PWM value (2^12 - 1 = 4095).
static constexpr uint32_t	kMinFrequencyHz = 24
	Minimum PWM frequency in Hz.
static constexpr uint32_t	kMaxFrequencyHz = 1526
	Maximum PWM frequency in Hz.

Private Member Functions
bool	validateChannel (hf_channel_id_t channel_id) const noexcept
	Validate channel ID is in range 0-15.

Private Attributes
Pca9685Handler *	parent_handler_
	Owning handler (not owned).
hf_frequency_hz_t	current_frequency_hz_ = 200
	Current global frequency.
Per-Channel State Cache
std::array< float, kMaxChannels >	duty_cache_
	Cached duty cycles (0.0-1.0).
std::array< uint16_t, kMaxChannels >	on_time_cache_
	Cached on-time values (phase offset).
std::array< bool, kMaxChannels >	channel_enabled_
	Channel enable state.

Friends
class	Pca9685Handler
	Allow handler to access internals.

Detailed Description

BasePwm adapter for all 16 PCA9685 PWM channels.

Wraps the PCA9685's 16 PWM channels as a HardFOC BasePwm instance. All hardware operations delegate to the parent Pca9685Handler, which in turn calls the typed PCA9685 driver.

Hardware Constraints

• Global frequency: The PCA9685 has a single oscillator with one prescaler. SetFrequency() on any channel changes the frequency for ALL channels. The adapter tracks the current frequency and returns it for any channel.
• 12-bit resolution: PWM values are 0-4095 (12-bit).
• Phase shift: Supported via the PCA9685's on-time offset. Each channel has a programmable on-time (0-4095) which creates a phase offset.
• No complementary outputs: SetComplementaryOutput() is unsupported.

Note

Created via Pca9685Handler::GetPwmAdapter(). The handler owns this instance.

Constructor & Destructor Documentation

Pca9685PwmAdapter()

Pca9685PwmAdapter::Pca9685PwmAdapter ( Pca9685Handler * parent_handler )

explicitnoexcept

Construct the PWM adapter.

Parameters

parent_handler

Pointer to the owning handler (must not be null).

~Pca9685PwmAdapter()

Pca9685PwmAdapter::~Pca9685PwmAdapter ( )

overridedefaultnoexcept

Default destructor.

Member Function Documentation

Deinitialize()

hf_pwm_err_t Pca9685PwmAdapter::Deinitialize ( )

overridenoexcept

Deinitialize (marks adapter as uninitialized).

DisableChannel()

hf_pwm_err_t Pca9685PwmAdapter::DisableChannel ( hf_channel_id_t channel_id )

overridenoexcept

Disable a PWM channel (set to full-off).

Parameters

channel_id

Channel number (0-15).

Returns

PWM_SUCCESS or error code.

EnableChannel()

hf_pwm_err_t Pca9685PwmAdapter::EnableChannel ( hf_channel_id_t channel_id )

overridenoexcept

Enable a PWM channel (restore its duty cycle from cache).

Parameters

channel_id

Channel number (0-15).

Returns

PWM_SUCCESS or error code.

GetDutyCycle()

float Pca9685PwmAdapter::GetDutyCycle ( hf_channel_id_t channel_id ) const

overridenoexcept

Get the cached duty cycle for a channel.

Parameters

channel_id

Channel number (0-15).

Returns

Duty cycle (0.0-1.0), or -1.0 on error.

GetFrequency()

hf_frequency_hz_t Pca9685PwmAdapter::GetFrequency ( hf_channel_id_t channel_id ) const

overridenoexcept

Get the current PWM frequency (global).

Parameters

channel_id

Ignored (frequency is global).

Returns

Frequency in Hz, or 0 on error.

Initialize()

hf_pwm_err_t Pca9685PwmAdapter::Initialize ( )

overridenoexcept

Initialize the PWM adapter (ensures parent handler is initialized).

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IsChannelEnabled()

bool Pca9685PwmAdapter::IsChannelEnabled ( hf_channel_id_t channel_id ) const

overridenoexcept

Check if a channel is enabled.

Parameters

channel_id

Channel number (0-15).

Returns

true if the channel is active.

SetComplementaryOutput()

hf_pwm_err_t Pca9685PwmAdapter::SetComplementaryOutput ( hf_channel_id_t primary_channel, hf_channel_id_t complementary_channel, hf_u32_t deadtime_ns )

overridenoexcept

Not supported by PCA9685.

Returns

PWM_ERR_UNSUPPORTED_OPERATION.

SetDutyCycle()

hf_pwm_err_t Pca9685PwmAdapter::SetDutyCycle ( hf_channel_id_t channel_id, float duty_cycle )

overridenoexcept

Set duty cycle for a channel (0.0-1.0).

Parameters

channel_id	Channel number (0-15).
duty_cycle	Duty cycle (0.0 = off, 1.0 = full on).

Returns

PWM_SUCCESS or error code.

SetDutyCycleRaw()

hf_pwm_err_t Pca9685PwmAdapter::SetDutyCycleRaw ( hf_channel_id_t channel_id, hf_u32_t raw_value )

overridenoexcept

Set raw PWM tick value for a channel.

Parameters

channel_id	Channel number (0-15).
raw_value	Off-time tick count (0-4095).

Returns

PWM_SUCCESS or error code.

SetFrequency()

hf_pwm_err_t Pca9685PwmAdapter::SetFrequency ( hf_channel_id_t channel_id, hf_frequency_hz_t frequency_hz )

overridenoexcept

Set PWM frequency (global – affects ALL channels).

The PCA9685 has a single prescaler so frequency is shared across all 16 channels. The channel_id parameter is accepted for API conformance but the frequency change applies globally.

Parameters

channel_id	Ignored (frequency is global).
frequency_hz	Frequency in Hz (24-1526).

Returns

PWM_SUCCESS or error code.

SetPhaseShift()

hf_pwm_err_t Pca9685PwmAdapter::SetPhaseShift ( hf_channel_id_t channel_id, float phase_shift_degrees )

overridenoexcept

Set phase shift for a channel (via PCA9685 on-time offset).

The PCA9685 supports staggered outputs by programming different on-time values per channel. This maps to phase shift: on_time = (phase_degrees / 360.0) * 4096

Parameters

channel_id	Channel number (0-15).
phase_shift_degrees	Phase offset in degrees (0-360).

Returns

PWM_SUCCESS or error code.

StartAll()

hf_pwm_err_t Pca9685PwmAdapter::StartAll ( )

overridenoexcept

Wake the PCA9685 from sleep (start all channels).

Returns

PWM_SUCCESS or error code.

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StopAll()

hf_pwm_err_t Pca9685PwmAdapter::StopAll ( )

overridenoexcept

Put the PCA9685 into sleep mode (stop all outputs).

Returns

PWM_SUCCESS or error code.

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UpdateAll()

hf_pwm_err_t Pca9685PwmAdapter::UpdateAll ( )

overridenoexcept

No-op (PCA9685 updates immediately on register write).

Returns

PWM_SUCCESS.

validateChannel()

bool Pca9685PwmAdapter::validateChannel ( hf_channel_id_t channel_id ) const

inlineprivatenoexcept

Validate channel ID is in range 0-15.

Friends And Related Symbol Documentation

Pca9685Handler

friend class Pca9685Handler

friend

Allow handler to access internals.

Member Data Documentation

channel_enabled_

std::array<bool, kMaxChannels> Pca9685PwmAdapter::channel_enabled_

private

Channel enable state.

current_frequency_hz_

hf_frequency_hz_t Pca9685PwmAdapter::current_frequency_hz_ = 200

private

Current global frequency.

duty_cache_

std::array<float, kMaxChannels> Pca9685PwmAdapter::duty_cache_

private

Cached duty cycles (0.0-1.0).

kMaxChannels

constexpr uint8_t Pca9685PwmAdapter::kMaxChannels = 16

staticconstexpr

Number of PWM channels on the PCA9685.

kMaxFrequencyHz

constexpr uint32_t Pca9685PwmAdapter::kMaxFrequencyHz = 1526

staticconstexpr

Maximum PWM frequency in Hz.

kMaxRawValue

constexpr uint16_t Pca9685PwmAdapter::kMaxRawValue = 4095

staticconstexpr

Maximum raw PWM value (2^12 - 1 = 4095).

kMinFrequencyHz

constexpr uint32_t Pca9685PwmAdapter::kMinFrequencyHz = 24

staticconstexpr

Minimum PWM frequency in Hz.

kResolutionBits

constexpr uint8_t Pca9685PwmAdapter::kResolutionBits = 12

staticconstexpr

PWM resolution in bits.

on_time_cache_

std::array<uint16_t, kMaxChannels> Pca9685PwmAdapter::on_time_cache_

private

Cached on-time values (phase offset).

parent_handler_

Pca9685Handler* Pca9685PwmAdapter::parent_handler_

private

Owning handler (not owned).

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The documentation for this class was generated from the following files:

• Pca9685Handler.h
• Pca9685Handler.cpp