use ads1015

[VitorFrost]

I am planning to use this to read an ADS1115 to read an pH sensor for Arduino. Do you have any suggestion where to start it? What should I look first?

[VitorFrost]

Does this helps you? https://github.com/msurguy/processing-mqtt-sensor-demo and https://github.com/adafruit/Adafruit_CircuitPython_ADS1x15/tree/e11d0414d695fc7d50e9a79c732e4901c27ceeb2

[CamDavidsonPilon]

Our current development HATs use the ADS1115, but we plan to use 1015 for production.

I am planning to use this to read an ADS1115 to read an pH sensor for Arduino.

Is it correct that Raspberry Pi <-> Arduino <-> ADS1115? What is the purpose of the Arduino?

Currently there aren't any Arduino tools in Pioreactor.

[VitorFrost]

Our current development HATs use the ADS1115, but we plan to use 1015 for production.

I am planning to use this to read an ADS1115 to read an pH sensor for Arduino.

Is it correct that Raspberry Pi <-> Arduino <-> ADS1115? What is the purpose of the Arduino?

Currently there aren't any Arduino tools in Pioreactor.

Actually, no. I am planning to use this sensor/module : https://www.e-tinkers.com/2019/11/measure-ph-with-a-low-cost-arduino-ph-sensor-board/ There are 3,3V of it, but they are very rare and expensiver . I am planning to use like this: Raspberry Pi <-> Logic level shifter <-> ADS1x15 <- pH Sensor

[VitorFrost]

Actually, pH sensing can be a must for bioreactors! Sometimes, it is more precise to control growth media addition by pH level, then by turbidimetry.

[CamDavidsonPilon]

Your setup makes sense to me. And it's over i2c, so like:

             i2c                     i2c      voltage
Raspberry Pi <-> Logic level shifter <-> ADS1x15 <- pH Sensor

Here's a really quick sketch of what the Pioreactor software might look like to read from the ADS1115:

# -*- coding: utf-8 -*-
# filename: ~/.pioreactor/plugins/sense_ph.py
import click

from pioreactor.whoami import get_unit_name, get_latest_experiment_name
from pioreactor.config import config
from pioreactor.background_jobs.base import BackgroundJob
from pioreactor.utils import local_persistant_storage
from pioreactor.utils.timing import RepeatedTimer
from pioreactor.hardware import SCL, SDA

from adafruit_ads1x15.analog_in import AnalogIn 
from adafruit_ads1x15.ads1115 import ADS1115 as ADS
from busio import I2C 

class PHSensor(BackgroundJob):

    published_settings = {
        "pH": {"datatype": "float", "settable": False},
    }

    def __init__(self, sample_rate, unit, experiment):

        self.ads = ADS(I2C(SCL, SDA), data_rate=128, gain=1)
        self.analog_in = AnalogIn(self.ads, 0)
        self.pH = None

        self.read_ph_timer = RepeatedTimer(
            interval=1/sample_rate, # convert to seconds
            function=self.read_ph,
            run_immediately=True,
        ).start()

    def read_ph(self):
        raw = self.analog_in.voltage

        with local_persistant_storage("ph_calibration") as cache:
            # this published to MQTT
            self.pH = raw_to_calibrated(raw, cache) #raw_to_calibrated to be defined... 

    def on_ready_to_sleeping(self) -> None:
        self.read_ph_timer.pause()

    def on_sleeping_to_ready(self) -> None:
        self.read_ph_timer.unpause()

    def on_disconnect(self) -> None:
        self.read_ph_timer.cancel()

@click.command(name="sense_ph")
def click_sense_ph():
    """
    Start the pH sensor
    """

    job = PHSensor(
        sample_rate=config.getfloat(),
        unit=get_unit_name(),
        experiment=get_latest_experiment_name(),
    )
    job.block_until_disconnected()

and it can be run with pio run sense_ph in the command line.

I'm guessing there's no additional work to do to "tell" the Raspberry Pi there's a level shifter...

[VitorFrost]

Thanks for the file sense_ph.py Just to clarify, if I am doing it wright: I need to put this file in the folder /home/pi/.pioreactor/plugins then run the command pio run sense_ph ? Tried it, and got the error (tried to reboot it too):

pi@pioreactor:~ $ pio run sense_ph
Usage: pio run [OPTIONS] COMMAND [ARGS]...
Try 'pio run --help' for help.

Error: No such command 'sense_ph'.

Should the Web interface show anything? My /plugins page was empty too:

I have also installed de pip adafruit-ads1x15 library (https://learn.adafruit.com/raspberry-pi-analog-to-digital-converters/ads1015-slash-ads1115) and it worked fine.

Then I tried:

pio update --app
pio update --ui

NOTE: not able to do justpio update, it asked me what to update.

Nothing YET. Then, after another reboot, It showed on the Web UI, and also on the pio list-plugins. Beside this, when I try to run pio run sense_ph got:

Usage: pio run [OPTIONS] COMMAND [ARGS]...
Try 'pio run --help' for help.

Error: No such command 'sense_ph'.

And the webpage plugin link points to /Unknown (Can a plugin point to other pages outside pioreacors default plugins?)

Any suggestion? Is the problem related to not having a proper Pioreactor HAT? If so, can I bypass any HAT self-check?

[CamDavidsonPilon]

I don't think it's HAT related.

Hm, you shouldn't need to reboot so often. Things should "just work". If you run pio run --help, what shows up? I'm guessing:

Usage: pio run [OPTIONS] COMMAND [ARGS]...

Options:
  --help  Show this message and exit.

Commands:
  backup_database         (leader only) Backup db to workers.
  export_experiment_data  (leader only) Export tables from db.

If so, it's because your Pioreactor isn't set as a worker.

---

Ah! Looking back, this is an issue with first_boot again! I actually didn't give you the full list commands to run in my comment here.

You'll need to run the rest:

touch ~/home/pi/config_$(hostname).ini
printf "# Any settings here are specific to $(hostname), and override the settings in config.ini\n\n" >> /home/pi/.pioreactor/config_$(hostname).ini
cp ~/home/pi/config_$(hostname).ini ~/home/pi/.pioreactor/unit_config.ini
crudini --set ~/home/pi/config.ini network.inventory $(hostname) 1

The above edits your configuration file to make your Pioreactor a worker - then you should be able to run pio run sense_ph.

---

The script I gave you is just a demo, but there were a few silly bugs in it. Try this updated version, plus that provides some metadata so information on the /plugins page is filled in.

More full docs on plugins is available here

[VitorFrost]

@CamDavidsonPilon Thanks for the diagnosis! Yes, you was wright about pio run --help But the command above has an error! you have added a ~/home/pi/ where should be only ~/ I got this kind of error:

$ touch ~/home/pi/config_$(hostname).ini
touch: cannot touch '/home/pi/home/pi/config_pioreactor.ini': No such file or directory

Now I can finally see the reactor on the page /pioreactors

And only after a reboot I was able to run pio run sense_ph Thanks a lot for the work on the pH sensor! Now I have to figure out how to proper program in python and fix the name 'raw_to_calibrated' is not defined LOL