Risks:
The turnaround time for PCBs added with the shipping time of the XKT ICs and testing the PCB is cutting off much of our margin for error allowance and is dangerously late. 3 weeks for PCB turnaround, 1 week for IC chip shipping, and 1 week for PCB testing goes for a total of 5 weeks, which would not leave us enough time to remake the PCB if anything goes wrong.
To manage this, we will make the PCB layout next week without specific values for the capacitors to have the PCB design basically ready except for specific values. Additionally, we will test the circuit on a breadboard before sending the PCBs out to fabricate, and ideally, we can choose a fabrication lab that will have a faster than 3-week turnaround.
Another risk is the latency of the BLE communication, since BLE only allows one server to be connect to one client at a time, and there is a minimum connection time of ~7ms required. Our current mitigation strategy is to daisy-chain multiple keys together so each seeed BLE board can connect as a client to one other board and also connect as a server to a different board. Aka the boards can for a chain of board1 -> board2 -> board3 -> board4 -> … -> Main board and board9-> board10 -> etc to minimize the connection switching necessary. The number of chains that would give the fastest connection is still to be determined next week.
Changes:
No changes were made to the design of the system since last week.
Schedule updates:
Since the IC and PCB will take at least a week to ship and our design was delayed due to having issues figuring out the wireless charging system, we have shifted later tasks such as writing/designing the configurator software up.
Team Work Adjustments:
The new design challenge of delivering enough current through the wireless inductive charging transmitter resulted in a week of much research and comparing pros and cons to creating the circuit ourselves and what types of chips we could feasibly get and use, and has pushed around our schedule such that we will have to push back integration of our entire wireless charging system to when the IC chips and coils arrive. Additionally, the PCB send out for fabrication was also delayed by this week and the IC chip shipping week, so in order to maximally use the weeks of waiting, we have adjusted our work assignments to preparing for when components arrive and focusing on other parts of our project that don’t require those components.