177 lines
5.2 KiB
Markdown
177 lines
5.2 KiB
Markdown
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# ADS1115 Module
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| Since | Origin / Contributor | Maintainer | Source |
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| :----- | :-------------------- | :---------- | :------ |
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| 2017-04-24 | [fetchbot](https://github.com/fetchbot) | [fetchbot](https://github.com/fetchbot) | [ads1115.c](../../../app/modules/ads1115.c)|
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This module provides access to the ADS1115 16-Bit analog-to-digital converter.
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!!! caution
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The **ABSOLUTE MAXIMUM RATINGS** for all analog inputs are `–0.3V to VDD+0.3V` referred to GND.
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## ads1115.read()
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Gets the result stored in the register of a previously issued conversion, e.g. in continuous mode or with a conversion ready interrupt.
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#### Syntax
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`volt, volt_dec, adc = ads1115.read()`
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#### Parameters
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none
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#### Returns
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- `volt` voltage in mV (see note below)
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- `volt_dec` voltage decimal (see note below)
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- `adc` raw adc value
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!!! note
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If using float firmware then `volt` is a floating point number. On an integer firmware, the final value has to be concatenated from `volt` and `volt_dec`.
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#### Example
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```lua
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local id, alert_pin, sda, scl = 0, 7, 6, 5
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i2c.setup(id, sda, scl, i2c.SLOW)
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ads1115.setup(ads1115.ADDR_GND)
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-- continuous mode
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ads1115.setting(ads1115.GAIN_6_144V, ads1115.DR_128SPS, ads1115.SINGLE_0, ads1115.CONTINUOUS)
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-- read adc result with read()
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volt, volt_dec, adc = ads1115.read()
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print(volt, volt_dec, adc)
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-- comparator
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ads1115.setting(ads1115.GAIN_6_144V, ads1115.DR_128SPS, ads1115.SINGLE_0, ads1115.CONTINUOUS, ads1115.COMP_1CONV, 1000, 2000)
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local function comparator(level, when)
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-- read adc result with read() when threshold reached
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volt, volt_dec, adc = ads1115.read()
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print(volt, volt_dec, adc)
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end
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gpio.mode(alert_pin, gpio.INT)
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gpio.trig(alert_pin, "both", comparator)
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-- read adc result with read()
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volt, volt_dec, adc = ads1115.read()
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print(volt, volt_dec, adc)
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```
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## ads1115.setting()
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Configuration settings for the ADC.
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#### Syntax
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`ads1115.setting(GAIN, SAMPLES, CHANNEL, MODE[, CONVERSION_RDY][, COMPARATOR, THRESHOLD_LOW, THRESHOLD_HI])`
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#### Parameters
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- `GAIN` Programmable gain amplifier
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* `ads1115.GAIN_6_144V` 2/3x Gain
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* `ads1115.GAIN_4_096V` 1x Gain
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* `ads1115.GAIN_2_048V` 2x Gain
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* `ads1115.GAIN_1_024V` 4x Gain
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* `ads1115.GAIN_0_512V` 8x Gain
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* `ads1115.GAIN_0_256V` 16x Gain
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- `SAMPLES` Data rate in samples per second
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* `ads1115.DR_8SPS`
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* `ads1115.DR_16SPS`
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* `ads1115.DR_32SPS`
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* `ads1115.DR_64SPS`
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* `ads1115.DR_128SPS`
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* `ads1115.DR_250SPS`
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* `ads1115.DR_475SPS`
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* `ads1115.DR_860SPS`
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- `CHANNEL` Input multiplexer for single-ended or differential measurement
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* `ads1115.SINGLE_0` channel 0 to GND
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* `ads1115.SINGLE_1` channel 1 to GND
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* `ads1115.SINGLE_2` channel 2 to GND
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* `ads1115.SINGLE_3` channel 3 to GND
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* `ads1115.DIFF_0_1` channel 0 to 1
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* `ads1115.DIFF_0_3` channel 0 to 3
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* `ads1115.DIFF_1_3` channel 1 to 3
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* `ads1115.DIFF_2_3` channel 2 to 3
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- `MODE` Device operating mode
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* `ads1115.SINGLE_SHOT` single-shot mode
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* `ads1115.CONTINUOUS` continuous mode
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- `CONVERSION_RDY` Number of conversions after conversion ready asserts (optional)
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* `ads1115.CONV_RDY_1`
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* `ads1115.CONV_RDY_2`
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* `ads1115.CONV_RDY_4`
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- `COMPARATOR` Number of conversions after comparator asserts (optional)
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* `ads1115.COMP_1CONV`
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* `ads1115.COMP_2CONV`
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* `ads1115.COMP_4CONV`
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- `THRESHOLD_LOW`
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* `0` - `+ GAIN_MAX` in mV for single-ended inputs
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* `- GAIN_MAX` - `+ GAIN_MAX` in mV for differential inputs
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- `THRESHOLD_HI`
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* `0` - `+ GAIN_MAX` in mV for single-ended inputs
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* `- GAIN_MAX` - `+ GAIN_MAX` in mV for differential inputs
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#### Returns
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`nil`
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#### Example
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```lua
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local id, sda, scl = 0, 6, 5
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i2c.setup(id, sda, scl, i2c.SLOW)
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ads1115.setup(ads1115.ADDR_GND)
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ads1115.setting(ads1115.GAIN_6_144V, ads1115.DR_128SPS, ads1115.SINGLE_0, ads1115.SINGLE_SHOT)
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```
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## ads1115.setup()
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Initializes the device on the defined I²C device address.
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#### Syntax
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`ads1115.setup(ADDRESS)`
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#### Parameters
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- `ADDRESS`
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* `ads1115.ADDR_GND`
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* `ads1115.ADDR_VDD`
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* `ads1115.ADDR_SDA`
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* `ads1115.ADDR_SCL`
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#### Returns
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`nil`
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#### Example
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```lua
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local id, sda, scl = 0, 6, 5
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i2c.setup(id, sda, scl, i2c.SLOW)
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ads1115.setup(ads1115.ADDR_GND)
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```
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## ads1115.startread()
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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.
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#### Syntax
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`ads1115.startread([CALLBACK])`
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#### Parameters
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- `CALLBACK` callback function which will be invoked after the adc conversion is done
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* `function(volt, volt_dec, adc) end`
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#### Returns
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- `nil`
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#### Example
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```lua
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local id, alert_pin, sda, scl = 0, 7, 6, 5
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i2c.setup(id, sda, scl, i2c.SLOW)
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ads1115.setup(ads1115.ADDR_GND)
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-- single shot
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ads1115.setting(ads1115.GAIN_6_144V, ads1115.DR_128SPS, ads1115.SINGLE_0, ads1115.SINGLE_SHOT)
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-- start adc conversion and get result in callback after conversion is ready
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ads1115.startread(function(volt, volt_dec, adc) print(volt, volt_dec, adc) end)
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-- conversion ready
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ads1115.setting(ads1115.GAIN_6_144V, ads1115.DR_128SPS, ads1115.SINGLE_0, ads1115.SINGLE_SHOT, ads1115.CONV_RDY_1)
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local function conversion_ready(level, when)
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volt, volt_dec, adc = ads1115.read()
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print(volt, volt_dec, adc)
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end
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gpio.mode(alert_pin, gpio.INT)
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gpio.trig(alert_pin, "down", conversion_ready)
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-- start conversion and get result with read() after conversion ready pin asserts
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ads1115.startread()
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```
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