Nora is our most recent approach to cramming in the features from recent prototypes, using only two layers and populating all of the components on one side. Nora is our smallest board with a LiPo charger yet, measuring just 23.5 mm x 23.5 mm.
Nora is the first version having the IRQ (or ‘interrupt’) from the nRF24L01+ radio connected to the micro controller. Additionally, the accelerometer and gyroscope IRQ is also connected to the micro controller, which was not the case with the Avoccado° prototypes before.
With this new IRQ connection, the an Avoccado° micro controller can be woken up by the gyroscope or accelerometer when there is movement, creating more opportunities for energy saving modes.
This round of PCBs was made through dirtypcbs.com, a panelizing service started by friendly hackers from dangerousprototypes.com. The castellated connectors (plated half holes) didn’t work well and silkscreen turned out real dirty, but that’s just as advertised. The PCBs are working fine as they are 100% e-tested and the faulty ones are included in the shipment, marked with a sharpie. There is no solder resist between the TQFP pins, next time with tweaked CAM settings for the mask layer. All in all I can recommend dirtypcbs.com and their website is not only hassle free but pretty funny!