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188 lines
5.9 KiB
Markdown
188 lines
5.9 KiB
Markdown
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[](https://github.com/marketplace/actions/arduino_ci)
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[](https://github.com/RobTillaart/Max44009/actions/workflows/arduino-lint.yml)
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[](https://github.com/RobTillaart/Max44009/actions/workflows/jsoncheck.yml)
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[](https://github.com/RobTillaart/MAX44009/blob/master/LICENSE)
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[](https://github.com/RobTillaart/MAX44009/releases)
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# MAX44009 I2C LUX sensor
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Library for MAX44009 / GY-49 I2C lux sensor.
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## Description
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a.k.a. GY-49
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The MAX44009 ambient light sensor is an I2C sensor, that has a 22 bit
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dynamic range from 0.045 lux to 188,000 lux.
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relates to https://github.com/RobTillaart/Max44007
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## Schema breakout max44009 / GY-49
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```cpp
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// breakout MAX44009 / GY-49
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//
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// +--------+
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// VCC |o |
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// GND |o |
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// SCL |o o| ADDRESS
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// SDA |o o| -INT
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// +--------+
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//
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// ADDRESS:
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// 0 = 0x4A
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// 1 = 0x4B
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//
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// INT:
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// Connect the INT pin to an pull up resistor
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// 0 = interrupt
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// 1 = no interrupt
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// connect to an LED or an interrupt pin of an Arduino
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//
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```
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## Interface
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- **enum class Boolean { True, False }** enum class to prevent bool to be implicitly casted to int.
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### Constructor
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- **Max44009(uint8_t address, uint8_t dataPin, uint8_t clockPin)** Constructor with dataPin (sda) and clockPin (scl) for ESP32 and ESP8266.
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- **Max44009(uint8_t address, begin = Boolean::True)** Constructor for other boards e.g. UNO.
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- **Max44009(begin = Boolean::True)** Constructor with default I2C address 0x4A == 74.
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- **void configure(uint8_t address, TwoWire \*wire, begin = Boolean::True)** Change I2C interface and address.
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- **bool isConnected()** returns true if the device address configured is available on I2C bus.
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### Basic
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- **float getLux()** read the sensor and return the value in LUX. If the value is negative, an error has occurred.
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- **int getError()** returns last error.
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```cpp
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// ERROR CODES
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#define MAX44009_OK 0
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#define MAX44009_ERROR_WIRE_REQUEST -10
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#define MAX44009_ERROR_OVERFLOW -20
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#define MAX44009_ERROR_HIGH_BYTE -30
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#define MAX44009_ERROR_LOW_BYTE -31
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```
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### Configure thresholds
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check datasheet for details
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- **bool setHighThreshold(float value)** sets the upper threshold for the interrupt
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generation (INT pulls LOW). Works only if INTE bit is set by **enableInterrupt()**.
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Function returns false if the value is out of range.
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- **float getHighThreshold()** returns the value set.
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- **bool setLowThreshold(float value)** sets the lower threshold for the interrupt
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generation (INT pulls LOW). Works only if INTE bit is set by **enableInterrupt()**.
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Function returns false if the value is out of range.
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- **float getLowThreshold()** returns the value set.
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- **void setThresholdTimer(uint8_t value)** Time the threshold needs to be exceeded,
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defined in steps of 100ms. 2 seems to be a practical minimum.
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- **uint8_t getThresholdTimer()** returns the value set.
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### Configure interrupts
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check datasheet for details
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- **void enableInterrupt()** enables the upper and lower threshold interrupts.
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- **void disableInterrupt()** disables the threshold interrupts.
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- **bool interruptEnabled()** returns 1 if the interrupt mode is enabled.
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- **uint8_t getInterruptStatus()** returns 1 if an interrupt has occurred.
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### Configure flags
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check datasheet for details
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- **void setConfiguration(uint8_t)** writes directly to configuration register.
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**warning** Use with care.
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- **uint8_t getConfiguration()** reads the current configuration register.
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### Configure sample mode
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check datasheet for details
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CCR = Current Divisor Ratio.
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TIM = Integration time.
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- **void setAutomaticMode()** in automatic mode the MAX44009 determines the CDR and TIM
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parameters.
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- **void setContinuousMode()** continuous mode uses more power than a "single" conversion.
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Advantage is that the latest data is always available fast.
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- **void clrContinuousMode()** uses less power so better for LOW power configurations.
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- **void setManualMode(uint8_t CDR, uint8_t TIM)** Set the Current Divisor Ratio and the
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integration time manually. Effectively disable automatic mode.
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- **int getIntegrationTime()** returns the set integration time in milliseconds
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```
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CDR = Current Divisor Ratio
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CDR = 1 ==> only 1/8th is measured
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TIM = Time Integration Measurement (table)
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000 800ms
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001 400ms
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010 200ms
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011 100ms
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100 50ms manual only
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101 25ms manual only
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110 12.5ms manual only
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111 6.25ms manual only
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```
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### Test functions
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Function for the conversion math, not meant to be used directly,
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but by making them public they become testable.
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- **float convertToLux(uint8_t datahigh, uint8_t datalow)** convert intern register
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format to a LUX value.
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## Examples
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**Max44009\examples\max44009_test01**
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- use for e.g. UNO (use voltage convertor!)
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**Max44009\examples\max44009_test02**
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- will **not** compile for UNO
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- use for e.g. ESP32
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## Notes
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Please be aware this is a **3.3 Volt device** so it should not be connected
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to an Arduino or other 5 Volt device directly. Use a level convertor to
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solve this.
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Do not forget to connect the address pin as you cannot read the sensor
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in a reliable way. As the line will float it will sometimes have the
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right address and sometimes not. (been there ;)
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## Future
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- improve documentation
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- merge MAX44007 library in the future. (shared base class?)
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#### MAX44007
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The MAX44007 is an almost identical sensor that uses a step size of 0.025.
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That implies the library is not useable 1 to 1 for the MAX4007, however some
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