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GY-63_MS5611/libraries/PCA9635/README.md
rob tillaart 250ecb7f6a 0.3.4 PCA9635
2022-05-16 18:25:10 +02:00

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Arduino CI Arduino-lint JSON check License: MIT GitHub release

PCA9635

Arduino library for PCA9635 I2C 8 bit PWM LED driver, 16 channel.

Description

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

library is related to the 8 channel PCA9634 class. (these might merge in the future)

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.
  • uint8_t channelCount() returns the number of channels = 16.

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).

Mode registers

  • 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).
  • uint8_t setMode1(uint8_t value) convenience wrapper.
  • uint8_t setMode2(uint8_t value) convenience wrapper.
  • uint8_t getMode1() convenience wrapper.
  • uint8_t getMode2() convenience wrapper.

Constants for mode registers

(added 0.3.4)

Name Value Description
PCA9635_MODE1_AUTOINCR2 0x80 RO, 0 = disable 1 = enable
PCA9635_MODE1_AUTOINCR1 0x40 RO, bit1
PCA9635_MODE1_AUTOINCR0 0x20 RO bit0
PCA9635_MODE1_SLEEP 0x10 0 = normal 1 = sleep
PCA9635_MODE1_SUB1 0x08 0 = disable 1 = enable
PCA9635_MODE1_SUB2 0x04 0 = disable 1 = enable
PCA9635_MODE1_SUB3 0x02 0 = disable 1 = enable
PCA9635_MODE1_ALLCALL 0x01 0 = disable 1 = enable
PCA9635_MODE2_BLINK 0x20 0 = dim 1 = blink
PCA9635_MODE2_INVERT 0x10 0 = normal 1 = inverted
PCA9635_MODE2_STOP 0x08 0 = on STOP 1 = on ACK
PCA9635_MODE2_TOTEMPOLE 0x04 0 = open drain 1 = totem-pole

These constants makes it easier to set modes without using a non descriptive bitmask. The constants can be merged by OR-ing them together, see snippet:

ledArray.writeMode(PCA9635_MODE2, 0b00110100);

// would become

uint8_t mode2_mask = PCA9635_MODE2_BLINK | PCA9635_MODE2_INVERT | PCA9635_MODE2_TOTEMPOLE;
ledArray.writeMode(PCA9635_MODE2, mode2_mask);

// or even

ledArray.setMode2(PCA9635_MODE2_BLINK | PCA9635_MODE2_INVERT | PCA9635_MODE2_TOTEMPOLE);

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 I2C communication error

Operation

See examples

Future

  • improve documentation
  • unit tests
  • add examples
  • merge with PCA9634 and a PCA963X base class if possible