<aside> 💡 In this post I want to share about TimeStat, a project turned to SaaS that has gained traction and is in use across 200+ construction companies through out NYC. With over 3000 API calls being handled by the backend daily.

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Identifying problems for Contractors

• Contractors/Sub-contractors have multiple sites. Often workers must go from one site to another, as needed, this opens the door to accounting problems.
• Various trades are present at the same time, having a dedicated “office space” is sometimes impossible. What ends up happening is contractors send the crew to a job site, and expect them to show up on time, respect their break time, and of course to leave on time. You trust they show do all this, but how can one make sure?
• A paycheck error is the last thing a worker wants to see on a Friday. A situation that adds stress to both employer and employee.
  • For the employers, he must check his sheets which obviously adds to his workload. It add. Most use archaic methods like paper timesheets which are prone to human error and fraud, and at times difficult to read peoples handwriting, overall archaic and cumbersome for the digital age.

My Solution.

I developed a biometric attendance embedded device to keep track of workers throughout multiple job-sites. With the following requirements:

1. Wi-Fi Independent: because there is yet to be any infrastructure in a construction site.
2. Fraud-proof, to prevent workers from clocking in as other workers, or any other form of fraud.
3. Ease of use, the less the worker has to fiddle with it the better.

Device Demo

https://vimeo.com/850412571

Architecture- A broad view view:

https://www.figma.com/embed?embed_host=notion&url=https%3A%2F%2Fwww.figma.com%2Ffile%2F6IasDyK9rUrj11USUfZibM%2FTimeStat-Overview%3Ftype%3Dwhiteboard%26node-id%3D0%253A1%26t%3DEsmwNNFFWthJezyH-1

Embedded Systems Engineering

I knew nothing of PCB or 3D design, communication protocols, even soldering! . Below is my journey:

Research:How Cell Phones communicate:

I knew I could not depend on WiFi in a construction site, and from personal experience I knew cell phone signal can be limited (in basements and the higher up you go), especially if a building has thick walls. Keeping it short, after much research I discovered there exists a narrowband(NB) that improves upon signal penetration because of its wavelength.

I needed a modem capable of connect to existing NB networks of T-mobile, AT&T and Verizon. So looked up microcontrollers that had capable built in Modems. Now the question was…. ok how do I connect to a tower?

I heard of Twilio by watching a stock talk on MSNBC. So I decided to use their superSim to get my device online. After much documentation reading about AT commands, I succeeded.

Research: Communication Protocols. SPI, i2C, UART

Protocols used by various peripherals to connect to the microcontroller.

2)MQTT vs HTTP

• MQTT is lightweight in comparison with HTTP

3) Fingerprinting algorithm.

Not trying to re-invent the wheel, I went ahead and used open source modeling algorithms to match fingerprint input with stored data.