GY-63_MS5611/libraries/Max44009

MAX44009 I2C LUX sensor

Library for MAX44009 / GY-49 I2C lux sensor

Description

a.k.a. GY-49

The MAX44009 ambient light sensor is an I2C sensor, that has a 22 bit dynamic range from 0.045 lux to 188,000 lux.

Schema breakout max44009 / GY-49

//  breakout MAX44009 / GY-49
//
//      +--------+
//  VCC |o       |
//  GND |o       |
//  SCL |o      o| ADDRESS
//  SDA |o      o| -INT
//      +--------+
//
// ADDRESS:
// 0 = 0x4A
// 1 = 0x4B
//
// INT:
// Connect the INT pin to an pull up resistor
// 0 = interrupt
// 1 = no interrupt
// connect to an LED or an interrupt pin of an Arduino
//

Interface

• enum class Boolean { True, False } enum class to prevent bool to be implicitly casted to int

Constructor

• Max44009(address, dataPin, clockPin) Constructor with dataPin (sda) and clockPin (scl) for ESP32 and ESP8266
• Max44009(address, begin = Boolean::True) Constructor for other boards e.g. UNO.
• Max44009(begin = Boolean::True) Constructor with default I2C address 0x4A == 74.
• void configure(address, TwoWire *wire, begin = Boolean::True) Change I2C interface and address.
• bool isConnected() returns true if the device address configured is available on I2C bus.

Basic

• float getLux() read the sensor and return the value in LUX. If the value is negative, an error has occurred.
• int getError() returns last error.

// ERROR CODES
#define MAX44009_OK                     0
#define MAX44009_ERROR_WIRE_REQUEST    -10
#define MAX44009_ERROR_OVERFLOW        -20
#define MAX44009_ERROR_HIGH_BYTE       -30
#define MAX44009_ERROR_LOW_BYTE        -31

Configure thresholds

check datasheet for details

• void setHighThreshold(float) sets the upper threshold for the interrupt generation (INT pulls LOW). Works only if INTE bit is set by enableInterrupt().
• float getHighThreshold(void) returns the value set.
• void setLowThreshold(float) sets the lower threshold for the interrupt generation (INT pulls LOW). Works only if INTE bit is set by enableInterrupt().
• float getLowThreshold(void) returns the value set.
• void setThresholdTimer(uint8_t) Time the threshold needs to be exceeded, defined in steps of 100ms. 2 seems to be a practical minimum.
• uint8_t getThresholdTimer() returns the value set.

Configure interrupts

check datasheet for details

• void enableInterrupt() enables the upper and lower threshold interrupts.
• void disableInterrupt() disables the threshold interrupts.
• bool interruptEnabled() returns 1 if the interrupt mode is enabled.
• uint8_t getInterruptStatus() returns 1 if an interrupt has occurred.

Configure flags

check datasheet for details

• void setConfiguration(uint8_t) writes directly to configuration register. warning Use with care.
• uint8_t getConfiguration() reads the current configuration register.

Configure sample mode

check datasheet for details

CCR = Current Divisor Ratio.

TIM = Integration time.

• void setAutomaticMode() in automatic mode the MAX44009 determines the CDR and TIM parameters.
• void setContinuousMode() continuous mode uses more power than a "single" conversion. Advantage is that the latest data is always available fast.
• void clrContinuousMode() uses less power so better for LOW power configurations.
• void setManualMode(uint8_t CDR, uint8_t TIM) Set the Current Divisor Ratio and the integration time manually. Effectively disable automatic mode.
• int getIntegrationTime() returns the set integration time in milliseconds

    CDR = Current Divisor Ratio
    CDR = 1 ==> only 1/8th is measured

    TIM = Time Integration Measurement (table)
    000  800ms
    001  400ms
    010  200ms
    011  100ms
    100   50ms       manual only
    101   25ms       manual only
    110   12.5ms     manual only
    111    6.25ms    manual only

Examples

Max44009\examples\max44009_test01

• use for e.g. UNO (use voltage convertor!)

Max44009\examples\max44009_test02

• will not compile for UNO
• use for e.g. ESP32

Notes

Please be aware this is a 3.3 Volt device so it should not be connected to an Arduino or other 5 Volt device directly. Use a level convertor to solve this.

Do not forget to connect the address pin as you cannot read the sensor in a reliable way. As the line will float it will sometimes have the right address and sometimes not. (been there ;)