Add data from Pi GPIO

[NeilPatel84]

Hi! Running aqualinkD 2.5.2 on Raspi 3b and have it integrated with mqtt to home assistant.

I want to add a pressure sensor to my system and was planning on capturing the data through the GPIO pins. Anyway to route this through aqualinkd or would I need to set up a seperate workflow to get the pressure data to home assistant. For reference looking at this sensor.

https://a.co/d/eo7jSJM

[sfeakes]

In the current release, no AqualinkD can't do this. This functionality is in the development (and the dev release on GitHub has an early implementation). Should be ready in a few weeks.

[NeilPatel84]

Hey! Any update on this feature?

[sfeakes]

If you pull the latest dev release, it's there. I just haven't had time to write the documentation yet.
In aqualinkd.conf the below is an example of how to read the cpu temperature.

sensor_01_path=/sys/class/thermal/thermal_zone0/temp
sensor_01_label=CPU
sensor_01_factor=0.001000

the factor is simply a number to times the value in the file by. In case of a GPIO all you want is 1 or 0, so factor would be 1.
In the above example AqualinkD will post the converted value to MQTT aqualinkd/sensor/CPU with a value like 42.77

To read GPIO 11 you would need something like the below.

sensor_01_path=/sys/class/gpio/gpio11/value
sensor_01_label=GPIO11
sensor_01_factor=1

BUT, you will need to enable exporting the GPIO to the OS filesystem. How to do this will depend on your OS Release & Version

[petedavey]

@NeilPatel84 Did you ever complete this project? I had a similar idea and found your question. I, too would like to hook up a pressure sensor to my pentair DE filter to detect clogged filters. Did you use that sensor you linked and an ADC to the PI's GPIO I2S inputs? If you did, can you give me a full list of what you bought, how you connected it and how you configured it so I don't have to reinvent the wheel? Thank you!

[sfeakes]

AqualinkD will read any sensor that posts its information to the file system (Ie has kernel, sysfs, iio subsystem support). So any industrial sensor linked to an ADC converter based on ADS115 since they have great kernel support should be good.
I have not tried these components but if I was doing this I’d go with something like
ADC - https://www.sparkfun.com/sparkfun-qwiic-12-bit-adc-4-channel-ads1015.html
Sensor - https://www.dfrobot.com/product-1675.html

then add the below to /boot/config.txt
dtoverlay=ads1015,(probably need some other parameters)

The device should show up under /sys/bus/iio/devices/iio:device0/xxxxx. and use that in AqualinkD sensor config.

again I have not tested any of the above, but I have tested AqualinkD with other sensors, 1-wire, i2c etc

[petedavey]

Got it working! That was a fun project.

Used:

1. A ADC1115 at 3.3v https://www.amazon.com/dp/B0D9VTYRDR?ref=ppx_yo2ov_dt_b_fed_asin_title
2. a 5V 0-80 PSI sensor https://www.amazon.com/dp/B0F1FSNJ8P?ref=ppx_yo2ov_dt_b_fed_asin_title
3. a 10k / 20k resistor voltage divider to keep the sensor output below 3.3v (to not break GPIO inputs as the sensor is 5v it dumped 5v right out)

4. A python script to poll the sensor -
   import time
   import os
   import tempfile

import board
import busio
import adafruit_ads1x15.ads1115 as ADS
from adafruit_ads1x15.analog_in import AnalogIn

====== CONFIG ======

DIVIDER_RATIO = 0.6667 # 20k/(10k+20k) for 10k top, 20k bottom
ZERO_V = 0.50 # sensor output at 0 PSI (typically ~0.5V)
PSI_PER_V = 20.0 # (80psi)/(4.0V span) = 20 psi/volt above 0.5V
OUTFILE = "/run/aqualinkd/filter_psi"
INTERVAL_S = 2

====================

def atomic_write(path: str, text: str) -> None:
d = os.path.dirname(path)
os.makedirs(d, exist_ok=True)
fd, tmppath = tempfile.mkstemp(dir=d, prefix=".tmp_filterpsi_", text=True)
try:
with os.fdopen(fd, "w") as f:
f.write(text)
os.replace(tmppath, path)
os.chmod(path, 0o644)
finally:
try:
if os.path.exists(tmppath):
os.unlink(tmppath)
except Exception:
pass

def main():
i2c = busio.I2C(board.SCL, board.SDA)
ads = ADS.ADS1115(i2c)
ads.gain = 1 # +/-4.096V (stable for our ~0–3.1V at ADC)
chan = AnalogIn(ads, ADS.P0) # A0

# discard startup samples
for _ in range(10):
    _ = chan.voltage
    time.sleep(0.05)

while True:
    v_adc = chan.voltage
    v_sensor = v_adc / DIVIDER_RATIO
    psi = (v_sensor - ZERO_V) * PSI_PER_V
    if psi < 0:
        psi = 0.0

    atomic_write(OUTFILE, f"{psi:.2f}\n")
    time.sleep(INTERVAL_S)

if name == "main":
main()

5. Adding this to aqualinkd.conf
   sensor_poll_time = 5

sensor_01_path=/tmp/filter_psi
sensor_01_label=Filter PSI
sensor_01_factor=1
sensor_01_uom=psi

6. And a few brass fittings to tee the sensor underneath the pressure gauge on top of the DE filter

[sfeakes]

Very cool, well done.

just a thought, I’m sure you’ve already enabled i2c, so it you add “ dtoverlay=ads1115 ” to /boot/firmware/config.txt you should have a file in /sys/class/hwmon/hwmonX/device/ or /sys/bus/iio/devices/iio:deviceX/ you could point AqualinkD at directly and not have to use the python script.

[petedavey]

yeah i had issues with that running older buster image but yea.

the sensor when exposed to homebridge using your plugin shows as a celcius temp sensor and fluctuates between the right value (8.5) and 47 lol. but i can open a thread over there if you want. homekit sucks anyway, setting up HA instead.

[sfeakes]

The fluctuations are an issue that needs to be looked at, but the temp sensor is the only option available to HomeKit since the default home app doesn’t support much. If you are using AqualinkD’s HA autodiscovery it should already be in HA.
Let me know if you see fluctuations in HA as well?
If you have a way to monitor MQTT you should also look at the messages there as well.