cuplTag is a battery-powered NFC tag that logs ambient temperature and humidity. Tap it with an NFC-enabled phone and you will see timestamped readings appear in a web application. It’s a one-step operation that requires no configuration and no app installation!
Tap to View
Tap cuplTag with your phone to see temperature and humidity in an instant. It works like this:
- cuplTag automatically reads temperature and humidity every ten minutes³.
- Readings are stored² in a long URL¹.
- When you tap cuplTag with your phone, that URL opens automatically in a web browser.
- The cupl web application decodes the URL and extracts readings and metadata.
- Readings are timestamped, stored in a database, and displayed graphically.
- You can share a link to these graphs with your friends or download the data as a CSV.
¹ Sensor readings are encoded in a ~1 KB circular buffer within the URL.
² The URL is written to a dual interface EEPROM using I²C, which is readable from a phone using NFC.
³ Time interval is configurable from 3 minutes to 65535 minutes.
Use cuplTag Anywhere, Anytime
The cuplTag system offers unparalleled ease-of-use in a low cost package. There are many uses for this zero-install sensor. Here are just a few:
At Home
- Preventing mold growth by keeping relative humidity below 60% (source)
- Deterring dust mites and other small insects (source)
- Providing specific temperature and humidity profiles to promote plant growth
- Safely storing film, art, and other sensitive media
In Professional Environments
- Monitoring laboratories and production environments
- Helping glues and epoxies cure more quickly
- Keeping tabs on environmental conditions in your warehouse
- Protecting goods in transit
cuplTag Demo
cupl Web Application
Your cuplTag will be fully operable as soon as you insert a battery. cuplTags are pre-configured to display data using an instance of cuplfrontend that is hosted by our company, Plotsensor, Ltd. You are free to re-configure your tag so it uses your own instance of the cupldeploy web application.
Newly captured data are seamlessly stitched together with data from previous tag scans. You can easily see graphs of sample data with high temporal resolution by scanning cuplTag every few days.
The cupldeploy project is the parent of cupltag and the web application, which consists of cuplbackend and cuplfrontend. A tagged commit of cupldeploy represents a system version number (e.g. D3.7). Interoperable versions of each child project will share the same version number.
cuplTag Authentication
Authentication is important because tag data will be written to a database. In order to deter spoofing, each cuplTag ships with a unique and random secret key, which is used to generate an HMAC that is updated whenever the contents of the circular buffer change. (You can learn more about the specifics in our documentation). The HMAC is verified by the cupl web application, which knows the secret key. This feature prevents anyone without a cuplTag from generating a URL that appears to have come from one. The HMAC also guards against replay attacks, where a valid URL is obtained by a third party and fed to the web application more than once. It is highly unlikely that a cuplTag will produce the same HMAC twice.
Features & Limitations
For more detailed technical specifications, please see the cuplTag datasheet.
Features
- Connectivity: NFC (passive, tap-to-read)
- Data points: 188 (temperature & humidity) or 376 (temperature only)
- Battery life: 7+ years expected (depending on the operating environment)
- No Phone app install required
- Open source
Limitations
- Tap-to-read functionality requires an Internet connection on the scanning device
- cuplTag is not water resistant (a conformal coating was omitted for the sake of hackability)
Support & Documentation
cuplTag is a system comprised of hardware, firmware, frontend software, and a backend web applications, all of which are open source. That includes:
- A one page schematic
- KiCAD PCBA design files
- cuplTag MSP430 (firmware, docs (to be extended))
- cuplTag MSP430 firmware employs cuplcodec encoder, which is written in C, to generate the tag URL (code)
- cuplbackend uses the cuplcodec decoder, which is written in Python (PyPI, code, docs)
- cuplbackend timestamps samples and saves them into a database (code, API docs)
- Data are passed to and received from the cuplbackend web application by cuplfrontend, which is written in ReactJS (code, screenshots)
We welcome your questions through the Ask a technical question link below.
Manufacturing Plan
The cuplTag PCBA will be assembled by our contract electronics manufacturer (CEM) in China. We have ordered 250 units up front. To prevent the global chip shortage from slowing production, we have acquired reels of four components in advance. They will be free-issued to the CEM.
In response to a shortage of the MSP430FR2155TDBTR microcontroller, we have sourced an alternate part (MSP430FR2355TDBTR) for the first batch. This component, which is in the same family, is identical but for the addition of one peripheral (SAC) that is unused by cuplTag and disabled by default.
PCBAs will be shipped from the CEM to Plotsensor, Ltd. in Oxfordshire, UK, at which point we will:
- Quality Check the HT07R3 PCBAs
- Program the MSP430 with cuplTag firmware
- Write configuration strings to the MSP430 over the serial port (these specify the cuplTag serial, web application URL, etc.)
- Scan the cuplTag using NFC to verify that the cupl web application opens
- Verify that temperature and humidity readings are in line with a calibrated hygrometer manufactured by a third party
- Assemble the PCBA into its white plastic enclosure
- Stick the cupl logo on top and a CE mark on the bottom of that enclosure
- Ship the cuplTags in anti-static bags, together with jumpers and through-hole headers
Fulfillment & Logistics
After testing and packaging the production batch of cuplTags, we will send them on to Crowd Supply’s fulfillment partner, Mouser Electronics, who will distribute them to backers worldwide. You can learn more about Crowd Supply’s fulfillment service under Ordering, Paying, and Shipping in their guide.
Risks & Challenges
The two most significant risks we face pertain to the global chip shortage and our decision to use a new contract electronics manufacturer (CEM) for the cuplTag production run.
Global Chip Shortage
No problems are expected with the first 250 units that ship from Crowd Supply. We obtained components in advance, and these units are already in production. After this first batch is shipped, however, we face the possibility of delays on subsequent manufacturing runs. Fortunately, with only 16 unique components in the BOM, cuplTag does not require us to source very many parts.
New CEM
To sell cuplTag at a lower price, we have switched to a larger Chinese CEM. Prototypes were made with a European PCBA manufacturer. In order to reduce the risk of delays caused by a misunderstandings or an error, the CEM will ship us 10 fully populated PCBAs for inspection before we approve the remaining 240.
