PCA9635

Arduino library for PCA9635 I2C 8 bit PWM LED driver.

Description

This library is to control the I2C PCA9635 PWM extender. The 16 channels are independently configurable is steps of 1/256. this allows for better than 1% fine tuning of the duty-cycle of the PWM signal.

Interface

Constructor

PCA9635(uint8_t deviceAddress, TwoWire *wire = &Wire) Constructor with I2C device address, and optional the Wire interface as parameter.
bool begin() initializes the library after startup. Mandatory.
bool begin(uint8_t sda, uint8_t scl) idem, ESP32 ESP8266 only. Library does not support multiple Wire instances (yet).
void reset() resets the library to start up conditions.
bool isConnected() checks if address is available on I2C bus.

LedDriverMode

uint8_t setLedDriverMode(uint8_t channel, uint8_t mode) mode is 0..3 See datasheet for full details.
uint8_t getLedDriverMode(uint8_t channel) returns the current mode of the channel.

LED mode	Value	Description
PCA9635_LEDOFF	0x00	led is 100% off, default @startup
PCA9635_LEDON	0x01	led is 100% on.
PCA9635_LEDPWM	0x02	set LED in PWM mode, 0..255
PCA9635_LEDGRPPWM	0x03	add LED to the GRPPWM*

* all LEDs in the group GRPPWM can be set to the same PWM value in one set. This is ideal to trigger e.g. multiple LEDs (servo's) at same time.

Read and write

uint8_t write1(uint8_t channel, uint8_t value) writes a single 8 bit PWM value.
uint8_t write3(uint8_t channel, uint8_t R, uint8_t G, uint8_t B) writes three consecutive PWM registers. typical use is to write R, G, B values for a full colour LED.
uint8_t writeN(uint8_t channel, uint8_t * array, uint8_t count) write count consecutive PWM registers. May return PCA9635_ERR_WRITE if array has too many elements (including channel as offset).
uint8_t writeMode(uint8_t reg, uint8_t value) configuration of one of the two configuration registers. check datasheet for details.
uint8_t readMode(uint8_t reg) reads back the configured mode, useful to add or remove a single flag (bit masking).

Group PWM and frequency

void setGroupPWM(uint8_t value) sets all channels that are part of the PWM group to value.
uint8_t getGroupPWM() get the current PWM setting of the group.
void setGroupFREQ(value) see datasheet for details.
uint8_t getGroupFREQ() returns the freq of the PWM group.

Miscellaneous

int lastError() returns PCA9635_OK if all is OK, and other error codes otherwise.

Error code	Value	Description
PCA9635_OK	0x00	Everything went well
PCA9635_ERROR	0xFF	Generic error
PCA9635_ERR_WRITE	0xFE	Tries to write more elements than PWM channels
PCA9635_ERR_CHAN	0xFD	Channel out of range
PCA9635_ERR_MODE	0xFC	Invalid mode
PCA9635_ERR_REG	0xFB	Invalid register
PCA9635_ERR_I2C	0xFA	PCA9635 I2C communication error

Operation

See examples

Future

improve documentation
unit tests
add examples

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