Introduction
Last year element14 challenged us to create an IoT Holiday Light and we delivered. This year, we were challenged to use the Texas Instruments TPS92512 and Wurth Elektronik parts and LEDs to create something useful. So I set out to utilise the LEDs as best as I can. My initial proposal was to create a lighting solution that can be used for home as well as industrial use. The solution included the capability to be accessed via a mobile device like a remote and wifi connectivity was proposed. My initial proposal is available at Multipurpose Modular Light Bar Project: [01]: The idea
As the challenge evolved, so did my understanding of our requirement and the design became more specific. I ended up designing a modular plug and play lighting solutions for our unborn child’s room such that it had enough brightness to compete with commercial solutions as well as double as a dimmable light to be useful as a night light. Unlike philips HUEs which comes in sets of 3 bulbs that are point sources of light and need a central hub to work, my solution consists of larger light panels that can connects to the internet directly and accessed individually. The proof of concept is demonstrated here and can be expanded to work with other types of requirements such as work bench lighting etc.
All the design documents are available as design logs and the source code is available at github should you choose to make one yourself. We are thankful to Texas Instruments, Wurth Elektronik and Element 14 for this opportunity and their support.
I received a kit as well as budget and the details are presented in the post at Multipurpose Modular Light Bar Project: [02]: The UnBoxing and Multipurpose Modular Light Bar Project: [03] Shopping for Parts
The design and build
The hero of this design is the TPS92512 LED driver module which is used to control the brightness of the LEDs. Initially, we tested the module with a variety of lights to understand the response of the LEDs and the heat generated by the LEDs. It was concluded that an array of LEDs can be connected such that they operate at much lower average current levels thus producing less heat per LED. This results in a larger spread of light in a panel format all the while reducing eliminating the need for heatsinks.
We also tested our functionality with the CC3200 as a source of PWM which will be responsible for the dimming effect in the panel. The only thing to beware of with the CC3200 is the rate at which analogWrite is called. We need to create a small delay such that the main loop does not refresh the PWM signal over and over again. More on this later. I wrote a guide to the CC3200 and explained my code in the post at Multipurpose Modular Light Bar Project: [06] Setting up a TI CC3200 with Energia.
We also designed PCBs for the system such that the TPS92512 module was converted into a booster pack. We are still awaiting production on that end but the complete instructions for design are given in my blogs post at Multipurpose Modular Light Bar Project: [04] PCBs in the making and Multipurpose Modular Light Bar Project: [05] Creating the Layout: Parts from Wurth Electronics DE
Thank you Wurth Elektronik for their excellent library support for the parts they sell.
The last part is the enclosure which must be aesthetically pleasing while serving its purpose and then we recycled an old PC monitor, emptied it’s electronics and fitted it with our own parts. The font was replaced with frosted glass and the empty space was covered using a greeting card that my wife gave me on our first anniversary. The complete story of the build is available at our post at Multipurpose Modular Light Bar Project: [09] Recycling a Computer Monitor with a little love and romance
This prototype was designed to be hung on a wall and we did.
The Interface
The last part is the user interface which is also very important and I created a website that uses javascript to turn your PC, laptop, tablet or smartphone into a remote. The same page is designed to work on a multitude of devices and the javascript exposes four buttons on the page titled “Baby Room”. Each of these four buttons is responsible for sending the relevant command to the iot.eclipse.org MQTT broker to which our CC3200 is listening. The received commands are translated into actions and our entire project works. The details of the webpage design are given in the post Multipurpose Modular Light Bar Project: [07] A little web development for a GUI
A more detailed explanation is presented with code of the javascript at Multipurpose Modular Light Bar Project: [08] MQTT Communications at the CC3200 - Javascript, PAHO and TLV protocol
The demonstration
The final demonstration is shown in the video below. Its’ a short video on the summary and the working of our project.
Conclusion
This project is a proof of concept and has no limits. I am hoping to receive the PCBs I designed soon and will be upgrading the project to an RGB model and creating a duplicate to work as my bench light. I have already had friends come over and ask me what this would cost if I made some for them hence I am also looking at reducing the BOM cost to create a commercial version. The website will add a security feature such that not everyone can access the page.
This was a very different experience from my past projects as I concentrated on a smaller portion rather than making a large build and I hope it helps someone out there. Once again our thanks to Texas Instruments and Wurth Electronic and element14 for their support.
Thanks.
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