260 lines
7.5 KiB
Markdown
260 lines
7.5 KiB
Markdown
# 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) and ADS1015 (12-Bit) analog-to-digital converters.
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Other chips from the same family (ADS1113, ADS1114, ADS1013 and ADS1014) are likely to work. Missing hardware features will be silently ignored.
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This module supports multiple devices connected to I²C bus. The devices of different types can be mixed.
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The addressing of ADS family allows for maximum of 4 devices connected to the same I²C bus.
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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.ads1115()
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Registers ADS1115 (ADS1113, ADS1114) device.
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#### Syntax
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`ads1115.ADS1115(I2C_ID, I2C_ADDR)`
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#### Parameters
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- `I2C_ID` - always 0
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- `ADDRESS` - I²C address of a device
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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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Registered `device` object
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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.reset()
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adc1 = ads1115.ads1115(id, ads1115.ADDR_GND)
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```
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## ads1115.ads1015()
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Registers ADS1015 (ADS1013, ADS1014) device.
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#### Syntax
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`ads1115.ads1015(I2C_ID, I2C_ADDR)`
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#### Parameters
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- `I2C_ID` - always 0
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- `ADDRESS` - I²C address of a device
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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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Registered `device` object
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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.reset()
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adc1 = ads1115.ads1015(id, ads1115.ADDR_VDD)
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adc2 = ads1115.ads1115(id, ads1115.ADDR_SDA)
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```
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## ads1115.reset()
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Reset all devices connected to I²C interface.
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### Syntax
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ads1115.reset()
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#### Parameters
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none
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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.reset()
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```
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# ADS Device
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## ads1115.device: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, raw, sign = device: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 in uV (see note below)
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- `adc` raw adc register value
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- `sign` sign of the result (see note below)
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!!! note
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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`.
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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.reset()
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adc1 = ads1115.ads1115(id, ads1115.ADDR_GND)
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-- continuous mode
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adc1: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, sign = ads1:read()
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print(volt, volt_dec, adc, sign)
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-- comparator
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adc1: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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gpio.trig(alert_pin)
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volt, volt_dec, adc, sign = ads1:read()
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print(volt, volt_dec, adc, sign)
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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, sign = ads1115:read()
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print(volt, volt_dec, adc, sing)
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-- format value in int build
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if sign then
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-- int build
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print(string.format("%s%d.%03d mV", sign >= 0 and "+" or "-", volt, volt_dec))
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else
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-- float build
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-- just use V as it is
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end
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```
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## ads1115.device:setting()
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Configuration settings for the ADC.
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#### Syntax
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`device:setting(GAIN, SAMPLES, CHANNEL, MODE[, CONVERSION_RDY][, COMPARATOR, THRESHOLD_LOW, THRESHOLD_HI[,COMP_MODE]])`
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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` ADS1115 only
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* `ads1115.DR_16SPS` ADS1115 only
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* `ads1115.DR_32SPS` ADS1115 only
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* `ads1115.DR_64SPS` ADS1115 only
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* `ads1115.DR_128SPS`
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* `ads1115.DR_250SPS`
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* `ads1115.DR_475SPS` ADS1115 only
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* `ads1115.DR_490SPS` ADS1015 only
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* `ads1115.DR_860SPS` ADS1115 only
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* `ads1115.DR_920SPS` ADS1015 only
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* `ads1115.DR_1600SPS` ADS1015 only
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* `ads1115.DR_2400SPS` ADS1015 only
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* `ads1115.DR_3300SPS` ADS1015 only
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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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- `COMP_MODE` Comparator mode
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* `ads1115.CMODE_TRAD` traditional comparator mode (with hysteresis)
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* `ads1115.CMODE_WINDOW` window comparator mode
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note: Comparator and conversion ready are always configured to non-latching, active low.
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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.reset()
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adc1 = ads1115.ads1015(id, ads1115.ADDR_GND)
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adc1:setting(ads1115.GAIN_6_144V, ads1115.DR_3300SPS, ads1115.SINGLE_0, ads1115.SINGLE_SHOT)
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```
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## ads1115.device: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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`device: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, sign) 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.reset()
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adc1 = ads1115.ads1115(id, ads1115.ADDR_VDD)
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-- single shot
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adc1: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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adc1:startread(function(volt, volt_dec, adc, sign) print(volt, volt_dec, adc, sign) end)
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-- conversion ready
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adc1: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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gpio.trig(alert_pin)
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volt, volt_dec, adc, sign = adc1:read()
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print(volt, volt_dec, adc, sign)
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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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adc1:startread()
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```
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