Flush Detection

Created on 22 Oct 2018

An IoT sensor for detecting toilet flushes and extracting insights

What if you could track every toilet flush on CMU campus in real-time? Improved maintenance, better environmentalism, traffic control: the possibilities are limitless.


Mitchell Yang


Alan Qiu


Raghu Venkatesh


Bobbie Chen

Part Cost Quantity Total
Particle Electron $69.99 3 $209.97
IoT connectivity + microcontroller
LIS3DH Triple-Axis Accelerometer $5.50 3 $16.50
Detecting flushes by vibration
Clear polycarbonate sheet $41.54 1 $41.54
Polycarbonate for an enclosure
Project Totals: 7 $268.01
Track 1 Base Budget: $250.00
Preferred Vendor Budget Bonus: $50.00
Remaining Budget: $31.99
Raghu Venkatesh 18 Jan 2019, 1:09 p.m. EST
1/16 - We connected Sara Z, the third and final sensor, to a urinal. Although the urinals only use 3.8 liters per flush compared to 6 liters per flush for the full toilets, the pipe still vibrates enough to activate the unit. Sara T has been performing questionably, but we gathered good data for Sara U over the course of Friday.
Bobbie Chen 17 Jan 2019, 5:53 p.m. EST
Wow, I didn't know marquee was still in style
Bobbie Chen 17 Jan 2019, 5:52 p.m. EST
mfy: "So how do you feel about hardware now?"
raghuv: "Why is it so hard to connect wires?"
Raghu Venkatesh 13 Jan 2019, 8:13 p.m. EST
10/22 - We created a project, the culmination of several semesters of plumbing projects on the part of Bobbie.
Raghu Venkatesh 13 Jan 2019, 8:13 p.m. EST
11/16 - We created a design document, inspired by the 18500 Capstone version.
Raghu Venkatesh 17 Jan 2019, 3:08 a.m. EST
1/13 - Struggling to receive a vibration, we created a secure mock toilet using Amazon package to model intense vibrational events sure to exceed 2, 4, and even 16gs of force. Although we eventually decided to cut sensitivity in half, our primary issue was faulty connections.
Raghu Venkatesh 17 Jan 2019, 3:01 a.m. EST
1/16 - Rather than struggling with soldering irons to melt plastic bags or carefully laying double sided tape down, we created our more elegant and resilient waterproof seal using cute little resealable bags from a mini kit and some hand-chewed Trident. We hesitate to submerge or jetstream our accelerometer, but we believe our device can handle the exhaust of almost any toilet flush.
Raghu Venkatesh 17 Jan 2019, 2:57 a.m. EST
1/15 - Rather than soldering 7 wires to each accelerometer, we decided to solder parts of a Nx1 female header strip. These were much easier to solder, though we had troubled when a wire broke off inside the header and we were forced to replace the entire thing.
Raghu Venkatesh 17 Jan 2019, 2:43 a.m. EST
Two flush detectors have been mounted to the toilets of WEH Men's 5, complete with a water resistant design. Data from the toilets is sent to a website POSTing JSON information about the event and battery.
Raghu Venkatesh 16 Jan 2019, 7:08 p.m. EST
We have maintained continuous detections with two devices. Our waterproof design with longer wires fails to send acceleration events, however. We continue to check the accuracy and tightness of our wiring.
Raghu Venkatesh 15 Jan 2019, 11:42 p.m. EST
We have set up our project so that when an event occurs, it can notify the appropriate audiences by text and.or email. Furthermore, we have included a geographic database of all the toilets we will be using. Lastly, we switched from the I2C to SPI interface, allowing us to receive several minutes of continuous data from the accelerometer. We duplicated our successful prototype, only to again struggle to maintain continuous communication.
Raghu Venkatesh 15 Jan 2019, 1:04 a.m. EST
1/15 - we connected our Electron to a Mac over a USB cable, to aid in debugging
Raghu Venkatesh 14 Jan 2019, 10:40 p.m. EST
1/14 - we read the accelerometer over the air
Raghu Venkatesh 14 Jan 2019, 7:49 p.m. EST
1/14 - we have met as a gang of four for the first time
Raghu Venkatesh 13 Jan 2019, 8:22 p.m. EST
1/13 - after giving our credit card information to Particle, we connected our board to the cellular network and successfully sent sample code.
Raghu Venkatesh 13 Jan 2019, 8:15 p.m. EST
1/7 - we checked in to see the progress we had made over break.
Raghu Venkatesh 13 Jan 2019, 8:14 p.m. EST
1/13 - we picked up all of our supplies from HH.
Raghu Venkatesh 13 Jan 2019, 8:14 p.m. EST
12/6 - we held a group meeting to divide up responsibilities and set goals for the project.
Raghu Venkatesh 13 Jan 2019, 8:13 p.m. EST
11/30 - we submitted our final parts list.