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 = adc1: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()