1 introduction

1.1 back in Ohio using my regular voice

1.2 espeak is no worse than operat0rs audio and we all love his shows.

2 the problem

2.1 where i live the water table is high and basement flooding is a problem https://en.wikipedia.org/wiki/Great_Black_Swamp

2.2 to counteract the water table problem houses have sumps in the basement

sump closet

sump close up

2.2.1 sumps consist of a basin where outside water is collected

2.2.2 a pump, usually electric, that drains the sump

2.2.3 also a good sump system will have some type of backup pump

2.3 the 'real' problem happens when the sump pump(s) fail

2.3.1 primary pumps fail in many ways, mechanical motor failures, floats sticking electrical outage

2.3.2 secondary pumps also fail battery problems, mechanical problems

2.3.3 i wanted a notification system that would let me know that the water level in my sump was rising. i wanted it set so that if the water level hits where the secondary system kicks in i would get some ind of notification. i wanted a system that would not use python or some kind of 'home spy' system available from some friendly corporation.

3 the solution

3.1 a raspberrry pi, a simple transistor circuit, a c library that allows access to the pi's gpio's, mutt mail client, some bash scripting and a cron job

The probe is meerly 2 wires on the end of a pvc pipe. one wire is higher up on the pipe than the other when both wires are submerged, the circuit is complete. the wires are just some old stuff from a stripped out ethernet cable. you could easily cascade anumber of these circuits and provide a water level meter something like this,

, instead of running leds, you'd hook each end to a gpio pin on the pie.

In picture 2, the closeup you can see the probe its the small pvc pipe with the blue wires running along the side. I attached the end of the wires to the pipe by stripping the ends and wrapping them around a small 1/2" self tapping screw. then I screwed one in towards the bottom and on higher up. the one higer up determines when the water alarm goes off.

4 implementation

4.1 raspberry pi 3b+

4.1.1 install slackware

https://sarpi.fatdog.eu/

slackware-arm

http://arm.slackware.com/

podcast

https://shows.acast.com/slackchat

4.1.2 access to gpio's

4.1.2.1 initially sysfs, its deprecated

https://www.kernel.org/doc/Documentation/ABI/obsolete/sysfs-gpio

4.1.2.2 i was unable to get libgpio to compile

4.1.2.3 other solutions python. wiringpi, project dead

4.1.2.4 a library pigpiod

http://abyz.me.uk/rpi/pigpio/pigpiod.html

4.1.2.5 slackbuilds pigpiod

https://slackbuilds.org/

4.1.3 the circuit

4.1.3.1 a rework of a forrest mims water alarm circuit

https://en.wikipedia.org/wiki/Forrest_Mims

circuit diagram