GY-63_MS5611/libraries/ADS1x15/README.md

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# ADS1X15

Arduino library for I2C ADC ADS1015, ADS1115, and similar.


## Description

This library should work for the devices mentioned below,
although not all sensors support all functionality.

| Device  | Channels | Resolution | Max sps | Comparator | ProgGainAMP | Notes  |
|:-------:|:--------:|:----------:|:-------:|:----------:|:-----------:|:-------|
| ADS1013 |    1     |     12     |  3300   |     N      |      N      |        |
| ADS1014 |    1     |     12     |  3300   |     Y      |      Y      |        |
| ADS1015 |    4     |     12     |  3300   |     Y      |      Y      |        |
| ADS1113 |    1     |     16     |  860    |     N      |      N      |        |
| ADS1114 |    1     |     16     |  860    |     Y      |      Y      |        |
| ADS1115 |    4     |     16     |  860    |     Y      |      Y      | Tested |

As the 1015 and the 1115 are both 4 channels these are the most
interesting from functionality point of view as these can also do
differential measurement.


## Interface

The address of the ADS1113/4/5 is determined by to which pin the **ADDR**
is connected to:

| ADDR pin connected to | Address | Notes   |
|:---------------------:|:-------:|:-------:|
|      GND              |   0x48  | default |
|      VDD              |   0x49  |         |
|      SDA              |   0x4A  |         |
|      SCL              |   0x4B  |         |


- **ADS1x15()** base constructor, should not be used.
- **ADS1013(address, TwoWire \*wire = &Wire)** Constructor with device address, 
and optional the Wire interface as parameter.
- **ADS1014(address, TwoWire \*wire = &Wire)** Constructor with device address, 
and optional the Wire interface as parameter.
- **ADS1015(address, TwoWire \*wire = &Wire)** Constructor with device address, 
and optional the Wire interface as parameter.
- **ADS1113(address, TwoWire \*wire = &Wire)** Constructor with device address, 
and optional the Wire interface as parameter.
- **ADS1114(address, TwoWire \*wire = &Wire)** Constructor with device address, 
and optional the Wire interface as parameter.
- **ADS1115(address, TwoWire \*wire = &Wire)** Constructor with device address, 
and optional the Wire interface as parameter.

The function **void setWireClock(uint32_t speed)** is used to set the clock speed 
of the used I2C interface. 

The function **uint32_t getWireClock()** is a prototype. 
It returns the value set by setWireClock().
This is not necessary the actual value. 
When no value is set **getWireClock()** returns 0.
Need to implement a read / calculate from low level I2C code (e.g. TWBR on AVR),
better the Arduino Wire lib should support this call (ESP32 does).

After construction the **ADS.begin()** need to be called. This will return false 
if an invalid address is used.
The function **bool isConnected()** can be used to verify the reading of the ADS.
The function **void reset()** is sets the parameters to their initial value as 
in the constructor.


#### Programmable Gain

- **void setGain(uint8_t gain)** set the gain value, indicating the maxVoltage that can be measured
Adjusting the gain allows one to make more precise measurements. 
Note: the gain is not set in the device until an explicit read/request of the ADC (any read call will do).
See table below.
- **uint8_t getGain()** returns the gain value (index).

| PGA value | Max Voltage | Notes   |
|:---------:|:-----------:|:-------:|
|      0    |   ±6.144V   | default |
|      1    |   ±4.096V   |         |
|      2    |   ±2.048V   |         |
|      4    |   ±1.024V   |         |
|      8    |   ±0.512V   |         |
|      16   |   ±0.256V   |         |

- **float getMaxVoltage()** returns the max voltage with the current gain.
- **float toVoltage(int16_t raw = 1)** converts a raw measurement to a voltage.
Can be used for normal and differential measurements.
The default value of 1 returns the conversion factor for any raw number.

The voltage factor can also be used to set HIGH and LOW threshold registers 
with a voltage in the comparator mode.
Check the examples.

```cpp
  float f = ADS.toVoltage();
  ADS.setComparatorThresholdLow( 3.0 / f );
  ADS.setComparatorThresholdLow( 4.3 / f );
```


#### Operational mode

The ADS sensor can operate in single shot or continuous mode. 
Depending on how often one needs a conversion one can tune the mode.
- **void setMode(uint8_t mode)** 0 = CONTINUOUS, 1 = SINGLE (default)
Note: the mode is not set in the device until an explicit read/request of the ADC (any read call will do).
- **uint8_t getMode()** returns current mode 0 or 1, or ADS1X15_INVALID_MODE = 0xFE.



#### Data rate

- **void setDataRate(uint8_t dataRate)** Data rate depends on type of device.
For all devices the index 0..7 can be used, see table below.
Values above 7 ==> will be set to the default 4.
Note: the data rate is not set in the device until an explicit read/request of the ADC (any read call will do).
- **uint8_t getDataRate()** returns the current data rate (index).

The library has no means to convert this index to the actual numbers
as that would take 32 bytes. 

Data rate in samples per second, based on datasheet numbers.

| data rate | ADS101x | ADS 111x | Notes   |
|:---------:|--------:|---------:|:-------:|
|     0     |   128   |   8      | slowest |
|     1     |   250   |   16     |         |
|     2     |   490   |   32     |         |
|     3     |   920   |   64     |         |
|     4     |   1600  |   128    | default |
|     5     |   2400  |   250    |         |
|     6     |   3300  |   475    |         |
|     7     |   3300  |   860    | fastest |


#### ReadADC Single mode

Reading the ADC is very straightforward, the **readADC()** function handles
all in one call. Under the hood it uses the asynchronous calls.
- **int16_t readADC(uint8_t pin)** normal ADC functionality, pin = 0..3. 
If the pin number is out of range, this function will return 0.

To read the ADC in an asynchronous way (e.g. to minimize blocking) one has to use three calls:
- **void requestADC(uint8_t pin)**  Start the conversion. pin = 0..3. 
- **bool isBusy()** Is the conversion not ready yet? Works only in SINGLE mode!
- **bool isReady()** Is the conversion ready? Works only in SINGLE mode!  (= wrapper around **isBusy()** )  
- **int16_t getValue()** Read the result of the conversion.


in terms of code
```cpp

  void setup()
  {
    // other setup things here
    ADS.setMode(1);               // SINGLE SHOT MODE
    ADS.requestADC(pin);
  }


  void loop()
  {
    if (ADS.isReady())
    {
      value = ADS.getValue();
      ADS.requestADC(pin);       // request new conversion
    }
    // do other things here
  }

```
See examples


## ReadADC Differential

For reading the ADC in a differential way there are 4 calls possible.

- **int16_t readADC_Differential_0_1()** returns the difference between 2 ADC pins.
- **int16_t readADC_Differential_0_3()** ADS1x15 only
- **int16_t readADC_Differential_1_3()** ADS1x15 only
- **int16_t readADC_Differential_2_3()** ADS1x15 only
- **int16_t readADC_Differential_0_2()** ADS1x15 only - in software (no async equivalent)
- **int16_t readADC_Differential_1_2()** ADS1x15 only - in software (no async equivalent)

The differential reading of the ADC can also be done with asynchronous calls.

- **void requestADC_Differential_0_1()** starts conversion for differential reading
- **void requestADC_Differential_0_3()** ADS1x15 only
- **void requestADC_Differential_1_3()** ADS1x15 only
- **void requestADC_Differential_2_3()** ADS1x15 only

After one of these calls one need to call
- **int16_t getValue()** Read the result of the last conversion.

The readiness of a CONTINUOUS conversion can only be detected by the **RDY** line.
Best to use an interrupt for this, see examples.


#### ReadADC continuous mode

To use the continuous mode one need three calls
- **void setMode(0)** 0 = CONTINUOUS, 1 = SINGLE (default).
Note: the mode is not set in the device until an explicit read/request of the ADC (any read call will do).
- **int16_t readADC(uint8_t pin)** or **void requestADC(uint8_t pin)** to get the continuous mode started.
- **int16_t getValue()** to return the last value read by the device. 
Note this can be a different pin, so be warned.
Calling this over and over again can give the same value multiple times.

By using **bool isBusy()** or **bool isReady()** one can wait until new data is available.
Note this only works in the SINGLE_SHOT modus.

In continuous mode one should use the **ALERT/RDY** pin to trigger via hardware the readiness of the conversion.
This can be done by using an interrupt.

See examples.


#### Threshold registers ==> mode RDY pin

If the thresholdHigh is set to 0x0100 and the thresholdLow to 0x0000
the **ALERT/RDY** pin is triggered when a conversion is ready.

- **void setComparatorThresholdLow(int16_t lo)** writes value to device directly.
- **void setComparatorThresholdHigh(int16_t hi)** writes value to device directly.
- **int16_t getComparatorThresholdLow()** reads value from device.
- **int16_t getComparatorThresholdHigh()** reads value from device.

See examples.


## Comparator

Please read Page 15 of the datasheet as the behaviour of the
comparator is not trivial.

NOTE: all comparator settings are copied to the device only after an explicit 
**readADC()** or **requestADC()**


#### Comparator Mode

When configured as a **TRADITIONAL** comparator, the **ALERT/RDY** pin asserts
(active low by default) when conversion data exceed the limit set in the
high threshold register. The comparator then de-asserts when the input
signal falls below the low threshold register value.

- **void setComparatorMode(uint8_t mode)** value 0 = TRADITIONAL 1 = WINDOW, 
- **uint8_t getComparatorMode()** returns value set.
  
  
If the comparator **LATCH** is set, the **ALERT/RDY** pin asserts and it will be
reset after reading the sensor (conversion register) again.
*An SMB alert command (00011001) on the I2C bus will also reset the alert state.*
*Not implemented in the library (yet)*

In **WINDOW** comparator mode, the **ALERT/RDY** pin asserts if conversion data exceeds
the high threshold register or falls below the low threshold register.
In this mode the alert is held if the **LATCH** is set. This is similar as above.


#### Polarity

Default state of the **ALERT/RDY** pin is **LOW**, can be to set **HIGH**.

- **void setComparatorPolarity(uint8_t pol)** 
Flag is only explicitly set after a **readADC()** or a **requestADC()**
- **uint8_t getComparatorPolarity()** returns value set. 
  

#### Latch

Holds the **ALERT/RDY** to **HIGH** (or **LOW** depending on polarity) after triggered
even if actual value has been 'restored to normal' value.

- **void setComparatorLatch(uint8_t latch)** 0 = NO LATCH, not 0 = LATCH
- **uint8_t getComparatorLatch()** returns value set.


#### QueConvert

Set the number of conversions before trigger activates.
The **void setComparatorQueConvert(uint8_t mode)** is used to set the number of
conversions that exceed the threshold before the **ALERT/RDY** pin is set **HIGH**.
A value of 3 (or above) effectively disables the comparator. See table below.

- **void setComparatorQueConvert(uint8_t mode)** See table below.
- **uint8_t getComparatorQueConvert()**  returns value set.

| value | meaning                           | Notes   |
|:-----:|:----------------------------------|:--------|
|   0   | trigger alert after 1 conversion  |         |
|   1   | trigger alert after 2 conversions |         |
|   2   | trigger alert after 4 conversions |         |
|   3   | Disable comparator                | default |


#### Threshold registers comparator mode

Depending on the comparator mode **TRADITIONAL** or **WINDOW** the thresholds registers
mean something different see - Comparator Mode above or datasheet.

- **void setComparatorThresholdLow(int16_t lo)** set the low threshold; take care the hi >= lo.
- **void setComparatorThresholdHigh(int16_t hi)**  set the high threshold; take care the hi >= lo.
- **int16_t getComparatorThresholdLow()** reads value from device.
- **int16_t getComparatorThresholdHigh()** reads value from device.


## Future ideas & improvements

- Improve documentation
- More examples ?
- SMB alert command (00011001) on I2C bus?


## Operation

See examples