Nanoshield_ADC

This is the Arduino software library to access the ADC Nanoshield (ADS1x15 IC) from Texas Instruments.

Library features include:

  • Analog to digital conversion with 16 bits resolution.
  • Continuous mode to capture measures with a given sample rate.
  • Gain adjust to pair the signal magnitude with the resolution.
  • Differential voltage measurements.
  • High threshold setting to trigger interruptions.

To install, just click Download ZIP and install it using Sketch > Include Library... > Add .ZIP Library in the Arduino IDE.

This library is based on the Adafruit_ADS1X15 library from Adafruit.

The following examples are provided:

  • Voltage: read a voltage in single-ended mode.
  • VoltageWithHighGain: read a voltage in single-ended mode with a high gain. Increasing the gain allows reading smaller voltages with increased resolution.
  • Voltage4Ch: read four voltages in a single ADC Nanoshield.
  • Voltage16Ch: using multiple boards. Read sixteen voltages across four units of the ADC Nanoshield. Make sure that the jumpers for the I2C address are properly configured to support this example.
  • DifferentialVoltage: read a differential voltage between inputs 2 (+) and 3 (-). The channels can be easily changed to 0 (+) and 1 (-).
  • Read4to20mA: how to read data from industrial 4-20mA sensors (or 4-20mA “transmistters”). Make sure to use the 4-20 ADC Nanoshield board for this example.
  • ContinuousMode: read data in continuous mode to achieve high sample rates.
  • ContinuousMode4Ch: read multiple channels in continuous mode.
  • Comparator: trigger interruptions on arduino using the ADC Nanoshield in comparator mode.
  • RawAdcValue: read the raw ADC value in single-ended mode.

Class Documentation

class Nanoshield_ADC

Public Functions

Nanoshield_ADC(uint8_t i2cAddress)

Constructor.

Instantiates an object to control the ADC Nanoshield converter.

See
begin()
Parameters
  • i2cAddress -

    The nanoshield I2C address on the bus.

void begin()

Initializes the module.

uint16_t readRegister(uint8_t i2cAddress, uint8_t reg)

Read an ADC Nanoshield register.

Return
The value of the addressed register.
Parameters
  • i2cAddress -

    I2C address of the ADC Nanoshield.

  • reg -

    Register address to read.

void writeRegister(uint8_t i2cAddress, uint8_t reg, uint16_t value)

Writes to Nanoshield ADC config register.

Parameters
  • i2cAddress -

    I2C address of the Nanoshield ADC.

  • reg -

    Config register address to write.

  • value -

    Value to write.

bool conversionDone()

Checks if there is data available to read.

Return
True if no conversion is being done and the value is ready to be read. Otherwise, false.

int16_t getLastConversionResults()

Reads the binary voltage requested when it is ready.

To use when in continuous mode. Same as readNext().

Return
The binary voltage representation.
See
readNext()

int16_t readNext()

Reads the binary voltage requested when it is ready.

To use when in continuous mode.

Return
The binary voltage representation.

int16_t readADC_SingleEnded(uint8_t channel)

Reads channel binary voltage.

Return
Binary representation of the voltage in the channel.
Parameters
  • channel -

    Channel to read. Must be in 0, 1, 2 or 3.

int16_t readADC_Differential_0_1()

Reads differential voltage in binary mode between channels 0(+) and 1(-).

Reads 16 or 12 bits representation of the difference between the voltage in channels 0(+) and 1(-).

Return
Binary representation of the differential voltage.

int16_t readADC_Differential_2_3()

Reads differential voltage in binary mode between channels 2(+) and 3(-).

Reads 16 or 12 bits representation of the difference between the voltage in channels 2(+) and 3(-).

Return
Binary representation of the differential voltage.

void setComparator(uint8_t channel, int16_t highThreshold, int16_t lowThreshold)

Sets the Nanoshield ADC in comparator mode.

In comparator mode, the Nanoshield sets the ALERT/RDY pin to LOW when the voltage read exceed a high threshold. This pin is set to HIGH again when the voltage read falls below a low threshold. The ALERT/RDY pin is connected to arduino D3 pin.

Parameters
  • channel -

    The channel to compare.

  • highThreshold -

    The high threshold.

  • lowThreshold -

    The low threshold.

void setNotComparator()

Turns comparator mode off.

Note that comparator mode needs the continuous mode. So when comparator mode is unset, continuous mode still set. Unset continuous mode too if necessary.

See
setContinuous()

bool isComparator()

Checks if in comparator mode.

Return
True if comparator mode is active. False if not.

void startComparator_SingleEnded(uint8_t channel, int16_t highThreshold, int16_t lowThreshold)

Sets the high threshold value to comparator mode.

The ADS1115 has a interrupt signal connected to arduino ALERT/RDY pin (D3) to notify voltages over a high threshold. To use this feature, the alert jumper on arduino must be closed and a interrupt handler must be set with attachinterrupt(6, <interruptHandler>, LOW), where <interruptHandler> is the function to be called on interrupt signal.

Parameters
  • channel -

    The channel to keep track of value. Must be in 0, 1, 2 or 3.

  • highThreshold -

    The high threshold set ALERT/RDY pin LOW.

  • lowThreshold -

    The low threshold to set ALERT/RDY pin HIGH.

void setContinuous(bool c)

Sets the library to work on continuous mode.

In continuous mode, the library will reads the voltage value based on a sample rate. For example, if reading at 860Hz, then 860 measures will be done in a second.

See

setSampleRate()

getSampleRate()

readNext()

conversionDone()

Parameters
  • c -

    True to activate continuous mode, false to deactivate continuous mode.

bool isContinuous()

Checks if in continuous mode.

Return
Ture if in continuous mode, false if not.

void setGain(Gain_t gain)

Sets the input gain.

The input gain is used to adjust the converter resolution to the signal magnitude. Greater gains adjusts lower voltages over the resolution.

See
Gain_t
Parameters
  • gain -

    A available gain from the Gain_t enumerator.

Gain_t getGain()

Gets the gain set on the Nanoshield ADC.

Return
A value from Gain_t enumerator.
See

Gain_t

setGain()

float getRange()

[brief description]

[long description]

Return
[description]

virtual void setSampleRate(uint16_t sps)

Sets the conversor sample rate on continuous mode.

See
setContiuous()
Parameters
  • sps -

    Sample rate. Possible values are:

    • If using Nanoshield_ADC12 (12 bits): 128, 250, 490, 920, 1600, 2400, 3300
    • If using Nanoshield_ADC (16 bits): 8, 16, 32, 64, 128, 250, 475, 860 If no one of the above, the closest lower value will be selected.

virtual uint16_t getSampleRate()

Gets actual Nanoshield_ADC sample rate.

Return
Actual sample rate set.

float read4to20mA(uint8_t channel)

Reads channel current from 4mA to 20mA.

Return
The current on channel from 4mA to 20mA.
Parameters
  • channel -

    Channel to read. Must be one of 0, 1, 2 or 3.

float readVoltage(uint8_t channel)

Reads channel voltage.

Return
The voltage read up to 5V.
Parameters
  • channel -

    Channel to read. Must be one of 0, 1, 2 or 3.

float readDifferentialVoltage01()

Reads voltage in differential mode between channels 0(+) and 1(-).

Reads the difference between voltages in channel 0(+) and 1(-). For example, if the voltage in both channels is the same, then the differential voltage is zero. Notice that the voltage margin in channels still 0V to 5V in relation to GND.

Return
The difference between the voltages in channel 0(+) and 1(-).

float readDifferentialVoltage23()

Reads voltage in differential mode between channels 2(+) and 3(-).

Reads the difference between voltages in channel 2(+) and 3(-). For example, if the voltage in both channels is the same, then the differential voltage is zero. Notice that the voltage margin in channels still 0V to 5V in relation to GND.

Return
The difference between the voltages in channel 2(+) and 3(-).

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