Complete reference documentation for all public methods and types in the PCA9685 driver.
Source Code
Core Class
PCA9685<I2cType>
Main driver class for interfacing with the PCA9685 PWM controller.
Template Parameter: I2cType - Your I2C interface implementation (must inherit from pca9685::I2cInterface<I2cType>)
Location: inc/pca9685.hpp
Constructor:
PCA9685(I2cType* bus, uint8_t address);
Methods
Initialization
| Method | Signature | Description |
EnsureInitialized() | bool EnsureInitialized() noexcept | Lazy initialization - ensures bus and device are ready |
IsInitialized() | bool IsInitialized() const noexcept | Check if driver has been initialized |
Reset() | bool Reset() noexcept | Reset device to power-on default state |
Frequency Control
| Method | Signature | Description |
SetPwmFreq() | bool SetPwmFreq(float freq_hz) noexcept | Set PWM frequency for all channels (24-1526 Hz) |
GetPrescale() | bool GetPrescale(uint8_t& prescale) noexcept | Get current prescale register value |
PWM Control
| Method | Signature | Description |
SetPwm() | bool SetPwm(uint8_t channel, uint16_t on_time, uint16_t off_time) noexcept | Set PWM on/off time for a channel |
SetDuty() | bool SetDuty(uint8_t channel, float duty) noexcept | Set duty cycle (0.0-1.0) for a channel |
SetAllPwm() | bool SetAllPwm(uint16_t on_time, uint16_t off_time) noexcept | Set all channels to the same PWM value |
SetChannelFullOn() | bool SetChannelFullOn(uint8_t channel) noexcept | Set channel to fully ON (100% duty) |
SetChannelFullOff() | bool SetChannelFullOff(uint8_t channel) noexcept | Set channel to fully OFF (0% duty) |
Power Management
| Method | Signature | Description |
Sleep() | bool Sleep() noexcept | Put PCA9685 into low-power sleep mode |
Wake() | bool Wake() noexcept | Wake PCA9685 from sleep mode |
Output Configuration
| Method | Signature | Description |
SetOutputInvert() | bool SetOutputInvert(bool invert) noexcept | Set output polarity inversion |
SetOutputDriverMode() | bool SetOutputDriverMode(bool totem_pole) noexcept | Set totem-pole or open-drain mode |
Error Handling
| Method | Signature | Description |
GetLastError() | Error GetLastError() const noexcept | Get last error code (single-error convenience) |
GetErrorFlags() | uint16_t GetErrorFlags() const noexcept | Get accumulated error flags (bitmask) |
HasError() | bool HasError(Error e) const noexcept | Check if a specific error flag is set |
HasAnyError() | bool HasAnyError() const noexcept | Check if any error flag is set |
ClearError() | void ClearError(Error e) noexcept | Clear a single error flag |
ClearErrorFlags() | void ClearErrorFlags(uint16_t mask = 0xFFFF) noexcept | Clear error flags by bitmask |
Configuration
| Method | Signature | Description |
SetRetries() | void SetRetries(int retries) noexcept | Set I2C retry count for register operations |
SetRetryDelay() | void SetRetryDelay(RetryDelayFn fn) noexcept | Set optional callback invoked between retries (e.g. 1 ms delay for bus recovery); default nullptr |
Types
Type Aliases
| Type | Definition | Description |
RetryDelayFn | void (*)() | Optional callback for delay between I2C retries; used with SetRetryDelay(). |
Enumerations
| Type | Values | Location |
Error | None, I2cWrite, I2cRead, InvalidParam, DeviceNotFound, NotInitialized, OutOfRange | inc/pca9685.hpp |
Register | MODE1, MODE2, LED0_ON_L, LED0_OFF_L, PRE_SCALE, etc. | inc/pca9685.hpp |
Constants
| Constant | Value | Description |
MAX_CHANNELS_ | 16 | Maximum number of PWM channels |
MAX_PWM_ | 4095 | Maximum PWM value (12-bit) |
OSC_FREQ_ | 25000000 | Internal oscillator frequency (25 MHz) |
I2C Interface
I2cInterface<Derived> (CRTP)
Hardware-agnostic I2C interface using the Curiously Recurring Template Pattern.
Location: inc/pca9685_i2c_interface.hpp
The interface is non-copyable and non-movable; use references or pointers to the concrete bus type.
| Method | Signature | Description |
Write() | bool Write(uint8_t addr, uint8_t reg, const uint8_t* data, size_t len) noexcept | Write bytes to a device register |
Read() | bool Read(uint8_t addr, uint8_t reg, uint8_t* data, size_t len) noexcept | Read bytes from a device register |
EnsureInitialized() | bool EnsureInitialized() noexcept | Ensure I2C bus is initialized and ready |
The driver supports an optional retry delay via SetRetryDelay() (a function pointer). The I2C implementation can expose a static delay (e.g. Esp32Pca9685Bus::RetryDelay) and the app passes it to the driver after construction.
