PCA9685 C/C++ Library

This is a C/C++ library for the PCA9685 PWM controller. It is designed to work on any Linux system, including the Raspberry Pi.

Installation

To install the library, clone the repository and run the following commands:

cd PCA9685
mkdir build && cd build
cmake ..
make
sudo make install

Usage

To use the library, include the header file in your source code:

#include <PCA9685/PCA9685.h>

Initialize the PCA9685 controller:

int fd = PCA9685_init("/dev/i2c-1", 0x40);

The first parameter is the I2C device file and the second parameter (optional) is the I2C address of the PCA9685 controller. The I2C device defaults to "/dev/i2c-1" and the address defaults to 0x40.

Alternatively, a pre-initialised I2C file descriptor can be used:

int fd = open("/dev/i2c-1", O_RDWR);
if (fd < 0) {
	// Error opening the I2C device
}

// Set the I2C slave address
if (ioctl(fd, I2C_SLAVE, addr) < 0) {
	// Error setting the I2C slave address
}

int fd = PCA9685_reset(fd, 0x40);

The PCA9685_init function also calls PCA9685_reset. It is not necessary to call PCA9685_reset if PCA9685_init is used.

The following function sets the PWM frequency of the PCA9685 controller (if frequency is not passed, it defaults to 50 Hz):

PCA9685_setPWMFreq(fd, 50);

Now the PCA9685 controller is ready to use. You can set the PWM duty cycle for each channel:

PCA9685_setPWMuS(fd, 0, 1500);

This sets the PWM duty cycle for channel 0 to 1500 microseconds. The second parameter is the channel number (0-15, default 0) and the third parameter is the pulse width in microseconds (default 1500).

The PCA9685_close function closes the I2C file descriptor:

PCA9685_close(fd);

Error Handling

The PCA9685_errorno variable contains the error code of the last function call. If the function call was successful, PCA9685_errorno is set to 0.

if (PCA9685_errorno != 0) {
	// Error handling
}

The PCA9685_strerror function returns a string describing the error code:

printf("Error: %s\n", PCA9685_strerror(PCA9685_errorno));

Table of error codes:

Error Code	Description
0	No error
1	Failed to open I2C device
2	Unable to set I2C slave address
3	Failed to write to I2C device
4	Failed to read from I2C device
5	Invalid channel number
6	Invalid pulse width
7	Invalid frequency
8	Invalid ON/OFF register values
9	Invalid I2C file descriptor
10	Invalid I2C address
11	Invalid I2C device file

License

This library is licensed under the MIT License. See the LICENSE file for more information.

Contributing

Contributions are welcome! Please open an issue or submit a pull request.