I'm trying to put together a "Proof of Concept" to show a potential client. I hope to sell it to him and others. Initially I'm looking to assemble & program Inexpensive Wireless temperature sensors that will send a unique ID, temperature & voltage (battery condition) to a WiFi Gateway/Bridge (which also has to be designed). Low speed is fine.
I don't want to design a PCB at this point until there's some volume & a business case.
I was thinking of a TI CC1101 or a Nordic nRF905 433mhz transceiver connected to an Arduino Nano (for programming) and a DHT11 or a DHT18B20. The CC1101 has a built in Temp sensor that's not great quality but it could work for a test. I'm leaning towards 433mhz, not 2.4G WifI or BLE, because the sensors will be in refrigerators & freezers which typically have at least one layer of metal. I've tested it with low power 433mhz transceivers that do pretty well. I'll test 2.4G later this week.
There are more advanced sub 1Ghz tranceivers (TI CC1310, 1350) with built in MCUs, but they are a Chip only and require a PCB to be designed, tested, etc.
Expect that most users will have 4-8 sensors connecting to a single Gateway.
The information will go to the Cloud where it can be viewed. Ultimately each customer will be able to log in and set the temperature ranges for their sensors and when he/she will get a text or email notification. IFTTT, MQTT?
Most weather/temperature sensors send packets every 60 seconds. It's probably OK to send it every ~3 minutes to save battery.
I'm thinking of using 2 AA or AAA 1.5V Lithium batteries (3Volts total) for the sensor nodes. They perform better in a cold environment. The Gateway would be plugged in to AC and run on 3-5V DC.
For the initial test you could hard code the Gateway with the username and password to get on the Internet. I could have it connect though my phone's WiFi for demo purposes.
I was thinking that eventually the Gateway would broadcast it's own network name (Like an Amazon Alexa does) and you'd connect to it with iOS and then connect the Gateway to the local Wifi connection.
Haven't sorted out how to connect the individual sensors if/when we go beyond the Prototype/POC.
I am open to your ideas.
I am not an Engineer but I do my best to learn whatever tech necessary. I can send you the transceiver specs and a link to the Tranceiver Modules from China.
It will be done in phases, not all at once.
Since I will be selling th service it is important to get customer feedback and revise as necessary.
LMK what you need and if you are qualified and interested in this project.
Cambridge MA USA