ADS1X15

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

For using I2C ADC with Raspberry pi or other SBC with Linux OS, you can check similar library here.

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.

Installation

Using the Arduino IDE Library Manager

Choose Tools -> Manage Libraries...
Type ADS1X15 into the search box.
Search a row with title ADS1X15 by Rob Tillaart.
Click the Install button to install the library.

Using Git

To using latest update of the library, you can clone this repository in Arduino library folder. Default library folder for windows is C:\Users{username}\Documents\Arduino and for linux is ~/Documents/Arduino/libraries/.

git clone https://github.com/chandrawi/LoRaRF-Arduino.git

Initializing

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

To initialize the library you must call constructor as described below.

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.

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.

For example.

#include "ADS1X15.h"

// initialize ADS1115 on I2C bus 1 with default address 0x48
ADS1115 ADS(0x48);

void begin() {
  if (!ADS.isConnected()) {
    // error ADS1115 not connected
  }
}

I2C clock speed

The function void setWireClock(uint32_t speed = 100000) is used to set the clock speed in Hz of the used I2C interface. typical value is 100 KHz.

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).

See - arduino/Arduino#11457

Question: should this functionality be in this library?

Configuration

Programmable Gain

void setGain(uint8_t gain) set the gain value, indicating the maxVoltage that can be measured Adjusting the gain allowing 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.

  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 conversions needed you 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 is described on table below.

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.

// read ADC in pin 0
ADS.readADC(0);

See examples.

To read the ADC in an asynchronous way (e.g. to minimize blocking) you need call three functions:

void requestADC(uint8_t pin) Start the conversion. pin = 0..3.
isBusy() (Is the conversion not ready yet?) or 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

  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)

// read differential ADC between pin 0 and 1
ADS.readADC_Differential_0_1(0);

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 you need to call

int16_t getValue() Read the result of the last conversion.

See examples.

ReadADC continuous mode

To use the continuous mode you need call three functions:

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.

void setup() {
  // configuration things here
  ADS.setMode(ADS.MODE_CONTINUOUS);
  ADS.requestADC(0);              // request on pin 0
}

void loop() {
  value = ADS.getValue()
  sleep(1)
}

See examples.

In continuous mode, you can't use isBusy() or isReady() functions to wait until new data available. Instead you can configure ALERT/RDY pin to trigger an interrupt signal when conversion data ready.

Configure RDY pin interrupt signal

Interrupt signals on the ALERT/RDY pin can be triggered every conversion data ready. This is done by setting Hi_thresh register MSB to 1 and the Lo_thresh register MSB to 0.

void setComparatorThresholdLow(0x8000)
void setComparatorThresholdHigh(0x7FFF)

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 calling readADC() or requestADC() functions.

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?

Examples

See examples.

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README.md

README.md

ADS1X15

Description

Installation

Using the Arduino IDE Library Manager

Using Git

Initializing

I2C clock speed

Configuration

Programmable Gain

Operational mode

Data rate

ReadADC Single mode

ReadADC Differential

ReadADC continuous mode

Configure RDY pin interrupt signal

Comparator

Comparator Mode

Polarity

Latch

QueConvert

Threshold registers comparator mode

Future ideas & improvements

Examples

Files

README.md

Latest commit

History

README.md

File metadata and controls

ADS1X15

Description

Installation

Using the Arduino IDE Library Manager

Using Git

Initializing

I2C clock speed

Configuration

Programmable Gain

Operational mode

Data rate

ReadADC Single mode

ReadADC Differential

ReadADC continuous mode

Configure RDY pin interrupt signal

Comparator

Comparator Mode

Polarity

Latch

QueConvert

Threshold registers comparator mode

Future ideas & improvements

Examples