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146 lines
5.1 KiB
Markdown
146 lines
5.1 KiB
Markdown
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[](https://github.com/marketplace/actions/arduino_ci)
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[](https://github.com/RobTillaart/AM232X/actions/workflows/arduino-lint.yml)
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[](https://github.com/RobTillaart/AM232X/actions/workflows/jsoncheck.yml)
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[](https://github.com/RobTillaart/AM232X/blob/master/LICENSE)
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[](https://github.com/RobTillaart/AM232X/releases)
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# AM232X
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Arduino library for AM2320 AM2321 and AM2322 I2C temperature and humidity sensor.
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## Description
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AM232X is a sensor similar to the DHT12 with an I2C interface.
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Although in theory this could enable multiple sensors on one bus
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the AM232X has a fixed address **0x5C** so one need to implement a
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multiplexing strategy to have multiple sensors in practice.
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See multiplexing below.
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Typical parameters
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| | range | accuracy | repeatability |
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|:------------|:----------:|:--------:|:-------------:|
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| Temperature | -40 - 80 | 0.5°C | ±0.1 |
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| Humidity | 0.0 - 99.9 | 3% | ±0.1 |
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| Sample time | 2 seconds | | |
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```
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// AM232X PIN layout AM2315 COLOR
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// ============================================
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// bottom view DESCRIPTION COLOR
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// +---+
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// |o | VDD RED
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// |o | SDA YELLOW
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// |o | GND BLACK
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// |o | SCL GREY
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// +---+
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//
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// do not forget pull up resistors between SDA, SCL and VDD.
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```
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## Interface
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### Constructor
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- **AM232X(TwoWire \*wire = &Wire)** constructor, optionally set Wire0..WireN.
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- **bool begin(uint8_t sda, uint8_t scl)** for ESP32 alike devices, returns true if device is connected.
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- **bool begin()** for AVR alike devices, returns true if device is connected.
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- **bool isConnected(uint16_t timeout = 3000)** returns true if device-address is found on I2C bus.
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As the device can be in sleep modus it will retry for the defined timeout (in micros) with a minimum of 1 try.
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minimum = 800 us and maximum = 3000 us according to datasheet.
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### Base calls
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- **int read()** fetches the values from the sensor.
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- **uint32_t lastRead()** returns milliseconds since start of last read.
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- **float getHumidity()** returns the last read humidity.
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- **float getTemperature()** returns the last read temperature.
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### Offset
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- **void setHumOffset(float offset)** set an offset to calibrate (1st order) the sensor.
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- **float getHumOffset()** return current offset, default 0.
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- **void setTempOffset(float offset)** set an offset to calibrate (1st order) the sensor
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- **float getTempOffset()** return current offset, default 0.
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### Control
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Functions to adjust the interval time the sensor may be called again.
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Default = 2000 ms (from datasheet).
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- **void setReadDelay(uint16_t rd = 0)** Tunes the time it waits before actual read can be done.
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Set readDelay to 0 will reset it to 2000 ms after a call to **read()**.
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- **uint16_t getReadDelay()** returns the above setting. Note that a value of zero (reset) will return 0 before the call and 2000 after the call to **read()**.
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### Misc
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check datasheet for details.
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- **int getModel()** idem
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- **int getVersion()** idem
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- **uint32_t getDeviceID()** idem
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- **int getStatus()**
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- **int getUserRegisterA()**
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- **int getUserRegisterB()**
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- **int setStatus(uint8_t value)**
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- **int setUserRegisterA(int value)**
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- **int setUserRegisterB(int value)**
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- **bool wakeUp()** function that will try for 3 milliseconds to wake up the sensor.
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## Operation
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See examples
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In setup() you have to call the **begin()** to initialize
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the Wire library and do an initial **read()** to fill the variables temperature and humidity.
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To access these values one must use **getTemperature()** and **getHumidity()**.
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Note that the sensor can go into sleep mode and one might need to call **wakeUp()**
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before the **read()**.
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## Multiplexing
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Multiplexing the AM232X can be done in several ways.
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This is not a complete list or tutorial but should get you started.
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1. Control the power line by means of an extra pin (+ transistor).
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Only switch on the sensor you want to use. Drawback might be time
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the sensor takes to boot and to be ready for the first measurement.
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2. Use an AND gate between the I2C SCL (clock) line and the I2C SCL
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pin of the sensors. This way one can enable / disable communication
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per sensor. This will still need an IO pin per sensor but does not
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have the "boot time" constraint mentioned above.
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3. Use a TCA9548A I2C Multiplexer, or similar. https://github.com/RobTillaart/TCA9548
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Which method fit your application depends on your requirements and constraints.
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## Warning
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The library has not been tested extensively yet so use at own risk.
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See also LICENSE
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## Future
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- update documentation
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- test more
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- add specific named classes ?
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- AM2320, AM2321, AM2322 ?
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- AM2315 - add type field ?
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