Poop Valve

poop-meter

Source code and design for the ultrasnoic septic tank monitor and main water shutoff.

• Doc: Documentation and technical notes.
• Deprecated Arduino and Perl code for the previous incarnation.
• Poop-Valve: Schematic for the water main shutoff valve.
• etc: Support files (Raspberry Pi startup script, crontab).
• src: Python source code.

TL;DR

Tracks the depth of the effluent in the septic holding tank. Notifies a human (SMS text) at intervals, more frequently as the tank gets more full. Shuts off the main water valve if the tank gets to a panic level.

Notable Notes

Software dependencies are spelled out in poopWatcher.py, but we also need a confguration file that tells us how to authenticate with Twilio to send text messages. This file can reside twilio.conf tin any of the curerent directory, in './etc/twilio.conf', or in '/usr/local/etc/twilio.conf'. For security reasons this file is not in the repository. Create the file and fill out at least the [twilio] stanza and add users to the recipient stanza as desired.

[twilio]
account_sid = **********************************
auth_token  = ********************************
from_phone = +1xxxyyyzzzz

[recipient]
dave = +1xxxyyyzzzz

A more detailed explanation is forthcoming.

Detailed Design

Super high level: we are multi-threaded and are a mix between polled and GPIO event driven threads. A side effect of this is that software bugs do not generally cause fatal errors. Polling is handled by poop.Poop.perSecond() which, first thing, schedules itself to run again in one second. It then, as prescribed by the poopinterval dictionary, dispatches an ADC sample of the poop tank, flashes the heartbeat LED, prints a status report to the log, does housekeeping, and (regarless of the dictionary) decides if we need to page a human and/or open/close the mains valve.

Simple, no?