Follow along with me in this video series as I build an IoT product from start to finish – check out the project page!

This Week’s Summary

Here’s a summary of what happened last week on my “Designing an IoT Product” video series:

• Did some background development testing with Arduino and Wi-Fi (see example), also have some older code I am going to reuse for an Arduino LCD temperature display (see example)
• Researched different types of sensors (air temp, water temp, light exposure, etc.) that would be useful to have in pool monitoring system (read full write up)
• Researched different types of pH and ORP probes for measuring pool water quality (read about them here) and ordered pH probe, ORP probe, and electronic conversion board
  • 3550_0 – ASP200-2-1M-BNC pH Lab Electrode – $25 USD from Phidgets
  • 1130_0 – pH/ORP Adapter – $30 USD from Phidgets
  • American Marine PINPOINT ORP/REDOX Probe – $54.95 from Amazon
• Researched alternative to Arduino board and looked at the Espressif ESP8266 (read post here)
• Purchased stand-alone pH meter for testing/verification against system – $ 10.99 USD from Amazon
• Purchased calibration solution test kit – $18.95 USD from Amazon

Design Notes and Current Challenges

• Probes: There are some cheaper probes available but some of them are not intended to be left in liquid for a pro-longed period of time so need to be careful what I purchase. Also some specifically state that they are not for use in salt water – probably because they will corrode quickly. I bought a pH and ORP probe that should be good to leave in my pool to test for extended period of time. I have a sand filter so don’t have to currently worry about salt systems yet.
• Going to focus on using Arduino board with probes and sensors submerged in pool to get first prototype working. Most important question to answer is can the probes be used to accurately predict overall water quality? Can this data be translated to customer in a way they understand it i.e. it’s time to add chlorine to your pool etc.
• Espressif ESP8266 only has one analog input so may not be enough for number of analog probes/sensors I want to use. The ESP32 would be perfect but as of to date it’s not quite ready for mainstream use. Sticking with Arduino is fine for time being but adding Wi-Fi and Bluetooth to it is more cumbersome and expensive potentially.
• Don’t like the screen options available on market for Arduino. Mostly character LCD screens or basic graphic LCD displays – neither option seem to be good fit for end product. Need to see what else is out there. I know 32 bit microcontrollers from ST Micro and Microchip have really good graphics options.

Business Notes and Current Challenges

• Final product will need high end (more expensive) probes that can withstand salt.
• What’s the breakdown of sand to salt to other pool filtration systems in the US? Need to get some numbers on this.
• How important is the physical display screen to end product? Will an LCD text display be good enough? Do I need a more advanced graphics display like color? Important decision to make after working prototype is proved out.

Plans for Next Week

• Get pH probe and conversion board up and running with Arduino board with LCD display. Compare results to commercial stand-alone pH meter to test accuracy. [Doesn’t look like I will be getting the probes until end of next week]
• Need to do more research on how to use measured pH and ORP to predict pool water quality. Chlorine levels? Try to compare to pH strips that report 6 or 7 chemicals.
• Need to start thinking about packaging and how to put probes in pool and how to make a quick prototype.