This will be another picture-less entry, but mainly to keep to rhythm of project logs.
Tomorrow I get the "smart" charger (integrated protection) and bluetooth (HC05) from the post-office (yay, another in-traffic biking experience). While I will not be able to play with this before the weekend (my laptop sleeps at work during week-days), good news is that I've found a pile of unused small LiPo cells at work. While some are a little puffed, some others are quite well. Most are 420mAh, a nice number at least for initial tests.
So, besides some other simple components (push-buttons, coin-battery) I think I have mostly what I will need for a while. I will have to wait for the hall sensor for another week, although I don't really need it to start some code for it.
Regarding the code, last weekend I've added ADC support to Teensy 3.x on NuttX and it seems to be working nicely. With this I will be able to measure the battery and detect charging/dis-charging condition.
Also, I've been thinking about the GUI and doing some crude sketches for guidance. As a test, I attempted to create a battery icon with different states (charging, critical, etc.) and for this I drew it on Gimp and converted it to XBM and the loaded it on the teensy. This worked great. I will probably try to sketch a logo/splash-screen for the device.
So next goal will probably be to complete a circuit on the protoboard featuring the charger and the battery and being able to detect charging and displaying charge level. For this I will probably deal with designing a GUI system based on pages (display-only for now, but including configuration screens later), which will change based on button presses.
On a final note, I created some repositories on GitLab for source-code and schematics, in case someone wants to check it out.