Working towards rev2

A project log for thumbMouse

Finger-mounted bluetooth pointer device, based on BlackBerry trackpad, for avoiding shoulder/wrist pain from mouse/laptop touchpad use

Matias N.Matias N. 06/30/2020 at 21:510 Comments

So recently I've been focused on BicycleCompanion, which I also submitted to HackadayPrize, since as I mentioned in last log I hit a bump with current design based on NRF51822. I still have no idea why I couldn't get Bluetooth to work but having only 16KB of RAM makes me wonder if it would work at all.

Anyways, yesterday I woke up to a first good news: I received another very kind donation on KoFi from someone interested in seeing thumbmouse move forward. After considering what I should do with the funds I realized the best would be to buy both an evaluation board and a module for a newer Nordic chip. This way, I could properly test any code before I finalize the PCB design. Then, I would already have a proper module for the PCB. I first try to see which Nordic chip to aim for. While I think nrf52840 is a very good option, I couldn't find BLE module for it with castellated pads from a respectable source. Since I already had a bad experience with the other module due to this, this was a must. In the end I decided to go with nrf52832, which is mostly similar. I found that Seeedstudio had some nice cheap options for both evaluation board and module. I decided to buy:

  • MDBT42Q, which uses a chip antenna
  • So, after ordering I decided to start revising the design I had, based on the SPI based BlackBerry trackpad series, to include this module. So far I have a reasonable layout of components without increasing the size too much, although I haven't put down traces yet. Right now the board looks something like this:

    The main changes are:

    And while taking a break from revising the design, I saw by chance that thubmouse was featured on hackaday! Really cool, aready got some feedback from there.

    The next step will probably be to buy some trackpads to check their size and see what is the best orientation for the connector. Anyways, as I have used cheap post por the Seeedstudio purchase, it may take about 30 days for stuff to arrive. So, I will probably have to wait for that to continue. My plan will probably be to again use Zephyr to have a quick test and then finalize the design. However, I'm considering working on adding Bluetooth handling on NuttX for the nRF52832, and base the code on that. That will take some time though, but I think it would be cool to do. However, once I have the design ready I can already order and test again with Zephyr. So expect this to be done not long after I receive these boards.