Designing the Open Muscle Band

The design of Open Muscle has gone through a few changes and the latest iteration has taken a more simplistic form.

Currently being developed on the RP2040 chip found in a version of the raspberry pi pico by waveshare, the Open Muscle band is utilizing the four ADCs provided by the main chip. Although one of them is used for internal temperature sensing it still gives enough feedback when it is directly connected to the Hall effect sensors we employ. Because the PCB architecture, and the schematic for that matter, that are being developed for version 3 are still a little way off we decided to produce a more simplistic working model using just those four ADCs provided by the RP2040.

The designs for the four sensor cells are still being worked on but until the new prototype PCB\’s come in we are focusing our efforts on creating a simple single Hall Effect cell and computer module unit together.
This design will have 4 pcb\’s with the same exact footprint but only one will contain a Waveshare version of the RP2040 zero. We have built 4 solder jumpers to assign the hall effect sensor to the right bus while also allowing all of the boards to have the same architecture.

So there will be four links in the Open Muscle proto-band. One will contain an RP2040 and a hall sensor while the other 3 will only have a single hall sensor and a solder jumper designating the proper output channel. With this version we also added the surface mounted hall sensor pads as well as the pin through ICs that we have used in prior prototypes.

Again, all of the design choices have been centered around two things: Keep the cost of materials to a minimum while providing ample specs, and making the unit in groups called Cells that can be arranged in a variety of use cases.