I made a lot of changes since the last update. The entire system is solely on the arm now. At this point, the previous iteration was more capable than this however, I couldn’t get past that cord coming down the arm.
This version replaces the Pi 4 with a Pi Zero W. There is a LiPoly battery, a charging board, and a step up voltage board to power it. The PiTFT display remains. I put my sewing skills to the test with this. There is a plastic cover sewn over the main components. With two velcro buckle straps.
There are several sensors displaying on the screen in the image above. The circuit playground on top is attached with velcro. Its sending temperature, accelerometer, button states, and EMG data. The EMG sensor, by Myoware is attached underneath, by velcro, where its pads connect to my skin.
You can also see the MAXREFDES117# pulse oximeter at the bottom. Yep, its facing outward.
There are a few configuration choices worth discussing. First, I have the interface on the inside of the wrist with the display oriented vertically. Most wrist-ama-jigs you will see, including watches, are on the outside of the wrist, and the displays are oriented horizontally. My thinking is that the inside configuration is more natural, and protected making the device more personally oriented.
With this configuration, the display comes withing your gaze more often than on the outside of the wrist. If you are using your smartphone, say taking a selfish, the wrist display is already facing you. Or if you are reading, holding the sides of a book, its facing you. The inside of the wrist is more concealed and protected, naturally since that’s were the vital parts are. This makes the device more protected as well.
The second configuration decision was to place the pulse oximeter facing outward. Smart watches have their pulse sensors facing toward the skin on the outside of the wrist for continuous reading. My workings with these sensors found them very inaccurate at that position. I have read that these types of sensors are less effective on darker skinned people (the green light), and motion adds much noise. I placed it facing outward so that one could place, and hold their finger on the pad to get a reading. A little bit of volition involved.
I intend to make it look more appealing, with a 3D printed enclosure at some point. I think this setup will allow me to focus more on the gaming and utility side of using this peripheral, especially now that the sensors are in place.
Booman's Workshop 