I have good news ! Our PCB is ready for production ! You can find the final electrical schematic : PCB_DROP.
We chose to use internal LDO with our nRF51822. Since last time, I added a kind of connector which is similar to SWD debugger to be able to connect an external circuit with a minimum place. With Alexis, we added ground planes in top and bottom layers. Moreover, we had to add a lot of via. Thanks to that, the ground would be equipotential. We also change the width of some path such as alimentation, or for the antenna, because there are some important constraints on them.
When we were done, Alexis said that we have to wait almost one night, to check if we had not done any mistake. And he was right ! Yersterday, I realize that since the beginning, I have wrong connections for the 16Mhz quartz ! It would have been a desaster if we send earlier the PCB to production ! But now, all issues are fixed.
I have taken a screenshot of our PCB top layer. The bottom layer only include our battery mount, and a few electrical path.
So… our drop circuit will not be any larger than 3 cm * 3 cm.
I hope we will receive the 30 of them really soon. But we probably will have to wait around two weeks, maybe more.
Yersterday, I also worked on the nRF51822 eval kit with Matthieu while Lau was doing the Android application. I was in charge with the drop program which has to create a table of messages, and to write the callback functions of a new BLE service for exchanging message. That is to say I write the processing part, while Matthieu wrote the BLE Service part (much more complicated). After that, we wanted to test our new service on our eval kit… but for a weird reason, when we should receive “message 1”, we only receive 4 characters “mess” and then, we was disconnected. We looked for the problem. I think we found it, but there was no more time to change the code and check it.
Then, I decided to update a little our website. If you are reading this blog with attention, their are not a lot of things you will learn, but elsewhere, it would help you to follow us 🙂
See you !