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96 lines
3.8 KiB
Markdown
96 lines
3.8 KiB
Markdown
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[](https://github.com/marketplace/actions/arduino_ci)
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[](https://github.com/RobTillaart/TSL235R/actions/workflows/arduino-lint.yml)
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[](https://github.com/RobTillaart/TSL235R/actions/workflows/jsoncheck.yml)
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[](https://github.com/RobTillaart/TSL235R/blob/master/LICENSE)
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[](https://github.com/RobTillaart/TSL235R/releases)
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# TSL235R
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Arduino library for the TSL235R light to frequency convertor.
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## Description
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This library does not measure the frequency.
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That should be done with an interrupt function (user code).
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The library provides functions to calculate the radiation and
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has functions to compensate e.g. for wavelength and voltage used.
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The library is not tested extensively yet.
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The sensor operating voltage is between 2.7 and 5.5 max.
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This can be set in the constructor, or runtime adjusted.
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For measurements below 1 uW/cm2 one should measure for multiple seconds.
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Above 1 uW/cm2 1 second or shorter is OK.
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Note that for longer and shorter measurements than 1 second one must
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convert the value to Hz, which is the number of pulses in 1 second.
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The library provides functions **irradiance()** to do that for you.
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## Connection
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Always check the datasheet.
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```
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// PIN 1 - GND
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// PIN 2 - VDD 2.7 V .. 5.5 V
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// PIN 3 - SIGNAL 1 Hz .. 800 KHz
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```
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## Interface
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- **TSL235R(float voltage = 5.0)** constructor, optionally one can give the operational voltage
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to add a small correction (< 1.5%).
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Default voltage is 5.0 Volts.
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- **float irradiance(uint32_t Hz)** returns the irradiance in uW/cm2.
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Note that Hz implies the measured pulses for 1 second.
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- **float irradiance(uint32_t pulses, uint32_t milliseconds)** returns the irradiance in uW/cm2.
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This formula is used for other duration than 1 second.
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To get irradiance in W/m2 one must divide by 100.
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- **float irradiance_HS(uint32_t pulses, uint32_t microseconds)** returns the irradiance in uW/cm2.
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This formula is used when the time is measured in microseconds.
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This is the most accurate measurement.
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- **float getFactor()** returns the inner conversion factor from Hz to Watt/cm2.
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- **void setWavelength(uint16_t wavelength = 635)** sets the wavelength so the formulas can use a
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correction factor.
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At the default wavelength of 635 nm the wavelength correction factor == 1.0.
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- **uint16_t getWavelength()** returns the set wavelength.
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- **float getWaveLengthFactor()** returns the wavelength correction factor.
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As the sensor is most sensitive around 750 nm this value helps to normalize the signal.
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This works only for (almost) monochromatic light.
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- **void setVoltage(float voltage)** sets the voltage so the formulas can use a correction factor.
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This voltage correction factor is rather small < 1.5%.
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Note: this voltage can be changed runtime.
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- **float getVoltage()** returns the set voltage, by constructor or by **setVoltage()**.
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Default voltage is 5.0 Volts.
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## Operations
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See examples for typical usage.
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## Future
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#### must
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- improve documentation
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- test test test
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#### should
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- default voltage should be a #define so people who use 3.3V processor
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can change the library with minimal effort.
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- irradiance(pulses, millis) can be given a default of 1000 millis.
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makes irradiance(Hz) obsolete.
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- move code from .h to .cpp
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#### could
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- investigate hardware solutions for e.g. divide by 100 or 1000 or so.
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- investigate correction factor for white light and mixed light sources.
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- investigate calibration factor for timing of processor used.
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