Building your own board for a specific Internet of Things project has many advantages. Well first, it means that you don’t end up with an ugly breadboard with wires going everywhere. This also adds a layer of safety and reliability to your project, as no wire can get disconnected during the use of the project. Finally, it means that in case your board is also interesting for other people, you already have a project that’s nearly ready for production & reselling.
However, building your own board for the Internet of Things can be tricky. And once it’s done, you are facing another issue: you need to find the right IoT platform that will support your project. In this article, we are going to see how the Particle Photon board can really help us solve these issues. Let’s start!
Introducing the Particle Photon
The Particle Photon is a development board developed by Particle, and it’s the perfect board for any IoT projects. Here is a picture of the board with headers assembled:
The board itself has several digital & analog I/Os, as well as an onboard WiFi chip and processor. But that’s not all: by default, the Photon board connects automatically to the Particle platform, which is an online cloud platform from which you can control your board. Therefore, you don’t have to find any cloud platform provider for the project: it’s all done for you automatically.
In this project, we are going to use the Photon board itself, but in the version that comes without the headers. With this version, we’ll be able to integrate it in a PCB design.
Specifications of the Board
As an example, we are going to build a very simple sensor board based on the Photon: a board with a temperature & humidity sensor, and an ambient light sensor. You can see the details of the project & the configuration on the corresponding article on the Open Home Automation blog:
We’ll also add a simple DC barrel connect and a voltage regulator so you can also power the board directly from a power source, without having your computer around.
This is the list of all the components that will be used in this project:
- Particle Photon without headers
- DHT11 sensor with 4.7 Ohm resistor
- 10K Ohm resistor
- MCP1825S 3.3V voltage regulator
- 1uF capacitor
- 4.7uF capacitor
- DC barrel jack
On the software side, you will need the latest version of the EAGLE software, that you can get from:
Designing the Schematic
We’ll now move to the first step: designing the schematic of the board. You first need to get the Particle library from the official GitHub repository:
To get the library, simply grab all the repository, and then get the .lbr file from the libraries folder. Then, place this file into the lbr folder of your Eagle repository. After that, restart Eagle.
It’s now time to make the design of the schematic. As it’s a relatively simple project, I won’t put all the steps here. I basically started by placing the Photon (without headers) on the schematic, and then I placed all the other components, ending with the sensors. This is the final result:
Making the Layout
We are now going to make the layout for the board. As it’s a very simple board that is there to illustrate the integration of the Photon board into a PCB design, I simply put all the components next to each other, without looking for the best optimisation of the available space.
After that, I changed the dimensions of the board, and then I routed the signals on the design. This is the final result:
Note that you can find all the design files on the GitHub repository of the project:
Building the Board
You can now actually build the board that we just designed. I recommend ordering the PCB from an online manufacturer, for example OSHPark. You can also find several articles on that topic on other articles of this blog.
Note that the article will be updated as soon as I receive the boards from production.
How to Go Further
In this article, we built a simple Internet of Things board based on the Particle Photon. Because this sensor board is using the Photon, it will automatically connect to the Particle platform as soon as it’s plugged in & configured with your WiFi name & password.
There are many ways to improve this project. You can for example integrate more sensors on the board, and monitor all the data from the Particle cloud platform. You could also replace the Photon board by what’s called the P1 chip, which is simply the chip used on the Photon board (plus an antenna), but without all the electronics around. Using the P1 chip, you will have more challenges to build the board, but it will result in a more compact board at the end.