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ADS1115 Module

Since Origin / Contributor Maintainer Source
2017-04-24 fetchbot fetchbot ads1115.c

This module provides access to the ADS1115 (16-Bit) and ADS1015 (12-Bit) analog-to-digital converters. Other chips from the same family (ADS1113, ADS1114, ADS1013 and ADS1014) are likely to work. Missing hardware features will be silently ignored.

This module supports multiple devices connected to I²C bus. The devices of different types can be mixed. The addressing of ADS family allows for maximum of 4 devices connected to the same I²C bus.

!!! caution

The **ABSOLUTE MAXIMUM RATINGS** for all analog inputs are `–0.3V to VDD+0.3V` referred to GND.

ads1115.ads1115()

Registers ADS1115 (ADS1113, ADS1114) device.

Syntax

ads1115.ADS1115(I2C_ID, I2C_ADDR)

Parameters

  • I2C_ID - always 0
  • ADDRESS - I²C address of a device
    • ads1115.ADDR_GND
    • ads1115.ADDR_VDD
    • ads1115.ADDR_SDA
    • ads1115.ADDR_SCL

Returns

Registered device object

Example

local id, sda, scl = 0, 6, 5
i2c.setup(id, sda, scl, i2c.SLOW)
ads1115.reset()
adc1 = ads1115.ads1115(id, ads1115.ADDR_GND)

ads1115.ads1015()

Registers ADS1015 (ADS1013, ADS1014) device.

Syntax

ads1115.ads1015(I2C_ID, I2C_ADDR)

Parameters

  • I2C_ID - always 0
  • ADDRESS - I²C address of a device
    • ads1115.ADDR_GND
    • ads1115.ADDR_VDD
    • ads1115.ADDR_SDA
    • ads1115.ADDR_SCL

Returns

Registered device object

Example

local id, sda, scl = 0, 6, 5
i2c.setup(id, sda, scl, i2c.SLOW)
ads1115.reset()
adc1 = ads1115.ads1015(id, ads1115.ADDR_VDD)
adc2 = ads1115.ads1115(id, ads1115.ADDR_SDA)

ads1115.reset()

Reset all devices connected to I²C interface.

Syntax

ads1115.reset()

Parameters

none

Returns

nil

Example

local id, alert_pin, sda, scl = 0, 7, 6, 5
i2c.setup(id, sda, scl, i2c.SLOW)
ads1115.reset()

ADS Device

ads1115.device:read()

Gets the result stored in the register of a previously issued conversion, e.g. in continuous mode or with a conversion ready interrupt.

Syntax

volt, volt_dec, raw, sign = device:read()

Parameters

none

Returns

  • volt voltage in mV (see note below)
  • volt_dec voltage decimal in uV (see note below)
  • adc raw adc register value
  • sign sign of the result (see note below)

!!! note

If using float firmware then `volt` is a floating point number, `volt_dec` and `sign` are nil. On an integer firmware, the final value has to be concatenated from `volt`, `volt_dec` and `sign`. On integer firmware `volt` and `volt_dec` are always positive, sign can be `-1`, `0`, `1`.

Example

local id, alert_pin, sda, scl = 0, 7, 6, 5
i2c.setup(id, sda, scl, i2c.SLOW)
ads1115.reset()
adc1 = ads1115.ads1115(id, ads1115.ADDR_GND)

-- continuous mode
adc1:setting(ads1115.GAIN_6_144V, ads1115.DR_128SPS, ads1115.SINGLE_0, ads1115.CONTINUOUS)
-- read adc result with read()
volt, volt_dec, adc, sign = ads1:read()
print(volt, volt_dec, adc, sign)

-- comparator
adc1:setting(ads1115.GAIN_6_144V, ads1115.DR_128SPS, ads1115.SINGLE_0, ads1115.CONTINUOUS, ads1115.COMP_1CONV, 1000, 2000)
local function comparator(level, when)
	-- read adc result with read() when threshold reached
	gpio.trig(alert_pin)
	volt, volt_dec, adc, sign = ads1:read()
	print(volt, volt_dec, adc, sign)
end
gpio.mode(alert_pin, gpio.INT)
gpio.trig(alert_pin, "both", comparator)

-- read adc result with read()
volt, volt_dec, adc, sign = ads1115:read()
print(volt, volt_dec, adc, sing)

-- format value in int build
if sign then
    -- int build
    print(string.format("%s%d.%03d mV", sign >= 0 and "+" or "-", volt, volt_dec))
else
    -- float build
    -- just use V as it is
end

ads1115.device:setting()

Configuration settings for the ADC.

Syntax

device:setting(GAIN, SAMPLES, CHANNEL, MODE[, CONVERSION_RDY][, COMPARATOR, THRESHOLD_LOW, THRESHOLD_HI[,COMP_MODE]])

Parameters

  • GAIN Programmable gain amplifier
    • ads1115.GAIN_6_144V 2/3x Gain
    • ads1115.GAIN_4_096V 1x Gain
    • ads1115.GAIN_2_048V 2x Gain
    • ads1115.GAIN_1_024V 4x Gain
    • ads1115.GAIN_0_512V 8x Gain
    • ads1115.GAIN_0_256V 16x Gain
  • SAMPLES Data rate in samples per second
    • ads1115.DR_8SPS ADS1115 only
    • ads1115.DR_16SPS ADS1115 only
    • ads1115.DR_32SPS ADS1115 only
    • ads1115.DR_64SPS ADS1115 only
    • ads1115.DR_128SPS
    • ads1115.DR_250SPS
    • ads1115.DR_475SPS ADS1115 only
    • ads1115.DR_490SPS ADS1015 only
    • ads1115.DR_860SPS ADS1115 only
    • ads1115.DR_920SPS ADS1015 only
    • ads1115.DR_1600SPS ADS1015 only
    • ads1115.DR_2400SPS ADS1015 only
    • ads1115.DR_3300SPS ADS1015 only
  • CHANNEL Input multiplexer for single-ended or differential measurement
    • ads1115.SINGLE_0 channel 0 to GND
    • ads1115.SINGLE_1 channel 1 to GND
    • ads1115.SINGLE_2 channel 2 to GND
    • ads1115.SINGLE_3 channel 3 to GND
    • ads1115.DIFF_0_1 channel 0 to 1
    • ads1115.DIFF_0_3 channel 0 to 3
    • ads1115.DIFF_1_3 channel 1 to 3
    • ads1115.DIFF_2_3 channel 2 to 3
  • MODE Device operating mode
    • ads1115.SINGLE_SHOT single-shot mode
    • ads1115.CONTINUOUS continuous mode
  • CONVERSION_RDY Number of conversions after conversion ready asserts (optional)
    • ads1115.CONV_RDY_1
    • ads1115.CONV_RDY_2
    • ads1115.CONV_RDY_4
  • COMPARATOR Number of conversions after comparator asserts (optional)
    • ads1115.COMP_1CONV
    • ads1115.COMP_2CONV
    • ads1115.COMP_4CONV
  • THRESHOLD_LOW
    • 0 - + GAIN_MAX in mV for single-ended inputs
    • - GAIN_MAX - + GAIN_MAX in mV for differential inputs
  • THRESHOLD_HI
    • 0 - + GAIN_MAX in mV for single-ended inputs
    • - GAIN_MAX - + GAIN_MAX in mV for differential inputs
  • COMP_MODE Comparator mode
    • ads1115.CMODE_TRAD traditional comparator mode (with hysteresis)
    • ads1115.CMODE_WINDOW window comparator mode

note: Comparator and conversion ready are always configured to non-latching, active low.

Returns

nil

Example

local id, sda, scl = 0, 6, 5
i2c.setup(id, sda, scl, i2c.SLOW)
ads1115.reset()
adc1 = ads1115.ads1015(id, ads1115.ADDR_GND)

adc1:setting(ads1115.GAIN_6_144V, ads1115.DR_3300SPS, ads1115.SINGLE_0, ads1115.SINGLE_SHOT)

ads1115.device:startread()

Starts the ADC reading for single-shot mode and after the conversion is done it will invoke an optional callback function in which the ADC conversion result can be obtained.

Syntax

device:startread([CALLBACK])

Parameters

  • CALLBACK callback function which will be invoked after the adc conversion is done
    • function(volt, volt_dec, adc, sign) end

Returns

  • nil

Example

local id, alert_pin, sda, scl = 0, 7, 6, 5
i2c.setup(id, sda, scl, i2c.SLOW)
ads1115.reset()
adc1 = ads1115.ads1115(id, ads1115.ADDR_VDD)

-- single shot
adc1:setting(ads1115.GAIN_6_144V, ads1115.DR_128SPS, ads1115.SINGLE_0, ads1115.SINGLE_SHOT)
-- start adc conversion and get result in callback after conversion is ready
adc1:startread(function(volt, volt_dec, adc, sign) print(volt, volt_dec, adc, sign) end)

-- conversion ready
adc1:setting(ads1115.GAIN_6_144V, ads1115.DR_128SPS, ads1115.SINGLE_0, ads1115.SINGLE_SHOT, ads1115.CONV_RDY_1)
local function conversion_ready(level, when)
	gpio.trig(alert_pin)
	volt, volt_dec, adc, sign = adc1:read()
	print(volt, volt_dec, adc, sign)
end
gpio.mode(alert_pin, gpio.INT)
gpio.trig(alert_pin, "down", conversion_ready)
-- start conversion and get result with read() after conversion ready pin asserts
adc1:startread()