This week I worked on the software programmer, the testing/validation, and the slides for the final presentation. For the software, I sketched up and implemented the UART transport protocol to program the keys. The interface first sends a bracket, followed by a comma separated list of key assignments, followed by a closing bracket. I also devised special codes such as RAISE for layer and other modifier keys. I then programmed the software to be able to send this set of assignments to the receiver microcontroller over UART. On the pure software side, I updated the application code to allow the dynamic resizing of the window, as well as the ability for it to remember where each key is after a resize. Next, I worked on the testing and verification of the various requirements. I first tested the wireless charging capabilities by connecting an ammeter in series with the wireless charging module and then measuring the current received by the battery. Next, I tested the latency of the overall system by connecting all the keys and recording them being pressed using the slow motion option on Ben’s phone. The latency was measured from the instance the key was pressed down to the bottom to the time the letter took to show up on the screen of the connected computer. Through this measurement I found that the typical latency is no more than 9 frames in total. Next, I tested the power consumption of the switch assembly by connecting an ammeter in series with a power supply set to provide 3.7v to the battery input of the Seeed XIAO board. Through this method, I found that the keys drew around 6.5mA when active and 0.7mA when sleeping. With this series of tests finished, I updated the final presentation to reflect these changes. Finally, I tested the ultimate range of the BLE receiver by taking a key as far as possible without losing connection. Ultimately, I was able to take the key around 45 feet back before running out of space indoors. However, the key was still connected despite this.
I am slightly behind on the software, as I was supposed to test the integration of the software and hardware components this week, but unfortunately I did not have time to verify. However, since the protocol should be the same, I do believe that there should be minimal issues. I will catch up by performing this test and then fixing any issues that arise before the presentation next week.
Next week I plan on working on the final report and the poster, as well as ensuring that the keys work correctly under a variety of conditions.