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:
- nRF52832 Micro Development board (includes a debugger chip on-board)
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:
- 20-pin FPC connector for 8250 series of trackpads (actually, I suspect many other models have the same pinout, will have to check)
- Battery Charger IC, to charge via
- Micro USB port
- Voltage level translation IC: since I have many lines to translate between 3.3v and 2.8v I had to use this chip
- Various pads exposing I/Os, VCC and GND for easy connection of switches, mouse wheel encoder or whatever one wants to add (someone mentioned a trackpoint, for example)
- 18.8 x 17.3 mm in size (22.2 x 17.3 mm including the protruding BLE module). This is almost the same in length as rev1 but about 3mm wider. I think it is still small enough to be usable.
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.