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GY-63_MS5611/libraries/PCA9551
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Rob Tillaart fc1c86def1 0.1.0 PCA9551
2023-07-20 16:35:33 +02:00
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examples 0.1.0 PCA9551 2023-07-20 16:35:33 +02:00
test 0.1.0 PCA9551 2023-07-20 16:35:33 +02:00
.arduino-ci.yml 0.1.0 PCA9551 2023-07-20 16:35:33 +02:00
CHANGELOG.md 0.1.0 PCA9551 2023-07-20 16:35:33 +02:00
keywords.txt 0.1.0 PCA9551 2023-07-20 16:35:33 +02:00
library.json 0.1.0 PCA9551 2023-07-20 16:35:33 +02:00
library.properties 0.1.0 PCA9551 2023-07-20 16:35:33 +02:00
LICENSE 0.1.0 PCA9551 2023-07-20 16:35:33 +02:00
PCA9551.cpp 0.1.0 PCA9551 2023-07-20 16:35:33 +02:00
PCA9551.h 0.1.0 PCA9551 2023-07-20 16:35:33 +02:00
README.md 0.1.0 PCA9551 2023-07-20 16:35:33 +02:00

README.md

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

PCA9551

Arduino library for PCA9551 I2C 8 bit PWM LED driver, 8 channel.

Description

This experimental library is to control the I2C PCA9551 PWM extender.

It is derived from the PCA9553 library and kept in sync if possible.

This device has seven possible I2C addresses 0x60 to 0x67, by means of 3 address lines. If you need to connect more PCA9551 devices to a single I2C bus you need a I2C multiplexer like https://github.com/RobTillaart/TCA9548.

The device has two PWM "generators", 0 and 1, and one can set the duty cycle and the frequency by means of a pre-scaler.

Every output channel 0..7 can select to which PWM generator it is connected, or if it is set to ON or OFF.

The output channels can also be used as generic GPIO, however that is not implemented in the first release.

From datasheet

Maximum output sink current is 25 mA per bit and 100 mA per package.

Power-On Reset (POR) initializes the registers to their default state, all zeroes, causing the bits to be set HIGH (LED off).

Related

Follow up series

Interface

#include "PCA9551.h"

Constructor

  • PCA9551(uint8_t deviceAddress, TwoWire *wire = &Wire) Constructor with I2C device address,
    Address = 0x60 .. 0x67 and optional the Wire interface as parameter.
  • bool begin() initializes the library after startup. Returns true if device address is available on I2C bus.
  • bool begin(int sda, int scl) idem, ESP32 ESP8266 only.
  • bool isConnected() checks if address is available on I2C bus.
  • uint8_t getAddress() returns I2C address.
  • uint8_t outputCount() returns the number of channels = 8.
  • uint8_t reset()

GPIO

  • uint8_t getInput() read all current output levels.
  • void pinMode(uint8_t pin, uint8_t mode) set output pin to INPUT or OUTPUT.
  • void digitalWrite(uint8_t pin, uint8_t value) set output pin HIGH or LOW.
  • uint8_t digitalRead(uint8_t pin) read current state of output pin.

Prescaler Frequency

Get and set the pre-scaler of the PWM generator.

  • void setPrescaler(uint8_t gen, uint8_t psc = 255) set pre-scaler for generator, default 255.
  • uint8_t getPrescaler(uint8_t gen) get the set value.

gen = 0 or 1

The main oscillator frequency can be divided by a pre-scaler. The period of BLINK = (PSC + 1) / 44 This gives the output a blink range of 0.172 Hz to 44 Hz.

Some "magic" pre-scalers. (to be confirmed).

psc Period Frequency
0 0.0227 44.00 Hz
1 0.0455 22.00 Hz
3 0.0909 11.00 Hz
7 0.1818 5.50 Hz
10 0.250 4.00 Hz
21 0.500 2.00 Hz
43 1.000 1.00 Hz
87 2.000 0.50 Hz
175 4.000 0.25 Hz
219 5.000 0.20 Hz
255 5.818 0.172 Hz

PWM

Get and set the duty cycle of the PWM generator.

  • void setPWM(uint8_t gen, uint8_t psc = 128) set PWM for generator, default value = 128.
  • uint8_t getPWM(uint8_t gen) get the set value.

gen = 0 or 1

The duty cycle of BLINK = (256 - PWM) / 256

pwm Duty Cycle
0 0%
64 25%
128 50%
192 75%
255 100%

Note: one might need a Gamma brightness correction - https://github.com/RobTillaart/GAMMA

Output Mode

  • uint8_t setOutputMode(uint8_t pin, uint8_t mode) set the mode for the selected output pin to one of 4 modi operandi. See table below.
    • pin == 0..7, mode == 0..3, see table below.
    • returns 0 if OK
    • returns error code if parameter is out of range.
  • uint8_t getOutputMode(uint8_t led) returns current setting.
    • pin == 0..7
    • returns mode, see table below.
    • returns error code if parameter is out of range.
Define Value Output pin
PCA9551_MODE_LOW 0 is set LOW (LED on)
PCA9551_MODE_HIGH 1 is set high-impedance (LED off; default)
PCA9551_MODE_PWM0 2 blinks at PWM0 rate
PCA9551_MODE_PWM1 3 blinks at PWM1 rate

Power On Reset

The PCA9551 will keep its settings as long as it is powered on. This means it can start with an previous configuration when uploading two different sketches short after each other.

To handle this the library has a reset() function which sets the device in the Power On state.

Error codes

These are kept similar to PCA9635 et al error codes.

Error code Value Description
PCA9551_OK 0x00 Everything went well
PCA9551_ERROR 0xFF Generic error
PCA9551_ERR_WRITE 0xFE
PCA9551_ERR_CHAN 0xFD output pin out of range / channel error
PCA9551_ERR_MODE 0xFC mode parameter out of range.
PCA9551_ERR_REG 0xFB
PCA9551_ERR_I2C 0xFA

Future

Must

  • improve documentation
  • keep in sync with PCA9553

Should

Could

Wont