Add powerful sensors to your next project! What will you make next?

The SensorCape is a BeagleBone Black add-on cape that provides extensive sensing capability to the already very capable BeagleBone Black platform. The SensorCape was developed for the Texas Instruments Intern Design Competition (2013).

I wanted to design an add-on that was as versatile and capable as the BeagleBone itself. Accomplishing this meant adding general functionality not included with the BeagleBone that would be useful in a variety of contexts.

The simplest way to add functionality is to increase the possibilities for interacting with the BeagleBone. For me, this meant adding various sensors to enable the BeagleBone to know more about the world around it.

Some broad requirements set for the SensorCape were:

  • Wide range of sensing capability
  • Relatively low power draw as compared to similar sensing products
  • Fast enough sensing to be useful in a broad range of applications
  • Minimal use of the BeagleBone GPIO pins

Starting off, I knew that I wanted to add some type of motion sensing as well as a temperature sensor. After browsing around Mouser and DigiKey I decided on a set of sensors that give the SensorCape the following capability:

  • 3-axis gyroscope
  • 3-axis accelerometer
  • 3-axis compass
  • Ambient light sensor
  • Ambient temperature sensor
  • Non-contact temperature sensor
  • Humidity sensor
  • Pressure sensor (Can detect changes in altitude)
  • 38 kHz IR sensor (Interfaces with common consumer electronics)
  • 4 push-buttons

In addition to these sensors, the SensorCape has also been designed with four user configurable LED’s and a production ready cape EEPROM which conforms to the requirements set in the BeagleBone Black System Reference Manual.

While he isn’t using the BeagleBone for the demo, this video from Sebastian Madgwick shows how the 9-axis device can be used to determine precise location and movements.

For more details on the sensors included on the SensorCape and how to use them you are referred to the SensorCape reference manual.

The SensorCape hardware has been designed by me (Michael Leonard) and will be released into the public domain under the Open Source Hardware license. The source files (KiCad) for this project are hosted at SolderPad which is a highly enabling platform that allows makers to easily share their designs. Additionally, you can download a .zip file of the source files below, including the bill of materials.

SensorCape Software Library

In addition to designing the hardware, I wanted to provide a software library that would allow users of the SensorCape to easily interact with the sensors on the board. I believe that one of the greatest assets of the Arduino environment is the incredible amount of libraries the community has provided, I hope that the BeagleBone community can meet that demand in the same way.

The software project is underway and is hosted at this repository on GitHub. The SensorCape library will eventually support both C and Python, with initial development focused on C. The intent is to finish developing the C library and to add a Python wrapper afterwards.

Thoughts on the SensorCape

The quotes below come from members of the BeagleBone community that have contacted me and expressed interest in the SensorCape. This makes it clear that, not only is the SensorCape ready for the community, but the community is ready for the SensorCape.

  • I am interested in using your SensorCape in a prototyping project for a potential new product, but haven’t found it on the BBB website or in the distribution channels – is there a sales outlet where I can buy some?

    Chuck B. via Email
  • I have been reading with much interest about your new BeagleBone Black cape. I was hoping that you were getting ready to sell them someday soon.

    Bobb C. via Email
  • I am interested in the sensor board for BeagleBone Black you designed, do they come pre-assembled?

    Mark R. via Email
  • This may become a milestone in the life of the #BeagleBone Black!

    Jason Z. via Google+
  • Hi there Michael. Just wanted to know if you have a spare SensorCape for sale right now? I would love to give it a spin in a show-off on our CarPC project.

    Luis L. via Google+
  • Agreed… I would buy one right now – depending on price, of course =)

    1
  • So, how do I get a sensor cape? That thing is loaded! I just put the BBB in the Adafruit enclosure so that cape would fit in there nicely and have this temperature sensor (among other things) that I’m after…

    Josh D. via fortune datko
  • This may become a milestone in the life of the #BeagleBone Black!

    Jason Z. via Google+

First Run Test

Here is the video from my Version 0.2 tests, I ran in to quite a few problems but everything is easily fixed or caused by manufacturing.

Version 0.9 Summary

After getting my version 0.2 boards back from manufacturing and assembly (a 3-week process) I have found and fixed all of the issues that plagued this first run. Some of the highlights;

  • I removed the Humidity sensor, the humidity sensor is a $10 part and I don’t think it is useful enough to warrant the extra cost.
  • I removed the LED’s, there are already four LED’s on the BBB so it would be redundant to include any more.
  • I switched to smaller, through hole push buttons.
  • I squeezed the design together to save space.
  • All of these changes together have saved about $15 in raw materials and that savings will be passed on to you.

What we are left with is a beautifully minimalistic board that still has a host of functionality. However, since this is a hobbyist board, I don’t think we’re aiming for minimal! :)

The amount of space I gained by making these changes was pretty significant, about half of the board is now free for other use, I am considering the following additions.

  • Two single row 6-pin headers spaced a few millimeters apart. I will send the I2C bus to these pins, as well as a few GPIO pins, all of the power signals (including ground), and two of the analog inputs. This will allow me, and others, to create single board add-ons for the SensorCape. Not that we need another platform to create add-on’s for, but this will allow people to customize their SensorCape without needing to add another cape entirely.
  • A prototyping grid. Using breadboard spacing I will fill the remaining area with a through hole prototyping area.

I wouldn’t have even added this update if it wasn’t absolutely necessary, but our design projects are due at midnight so here we are! If you have a better idea for use of this free space, let me know in the comments below.

If you would like to download the source files for this version of the SensorCape for BeagleBone Black then you can use the link below. This includes a zipped version of the KiCad source files, as well as the Gerber files and a bill of materials.

SensorCape for BeagleBone Black v0.9
SensorCape for BeagleBone Black v0.9
BBB_SensorCape_rev0.9_final_nocopfill.zip
Version: 0.9
597.3 KiB
663 Downloads
Details

Share your thoughts! Do you have a good idea for using this cape? Do you see something that could be done better? Let me know in the comments below.