This week, I was focused on 2 main things: helping to restructure our circuit power design to be much safer and getting a basic web app interface initialized.
In terms of the power redesign, Professor Tamal pointed out the large safety issue with our power supply in his feedback for our design documentation. Originally, we wired all 69 of our solenoids in parallel to a main power bus that would carry current to distribute amongst all the solenoids. This would mean that the bus would need a whopping ~30A supplied to it. This introduced a large safety concern and difficulty getting large enough wires for the bus that we could connect the solenoids to directly. Luckily, with some help from the player piano builders Discord we are a part of, I got some inspiration from the pictures showing people using multiple power supplies. With this we decided to split our large power supply into 9 smaller ones. This would allow us to group together batches of 8 solenoids and power them each with a 3A power supply. This is a much safer option since household and microcontroller electronics run on this amperage. This also allows us to also use more standard wire gauges and connectors for the solenoids.
In terms of the web app initialization, I created a preliminary app using Django as the overall framework and sqlite3 as the backend database. For our web app, we will be hosting a basic user audio playback interface consisting of controls to upload recordings, save recordings, and pause/play the piano playing. The only data we need to store are processed .wav files saved as text files describing the scheduled notes. We are using sqlite3 for the backend management engine since it is simple to use and I am familiar with it from learning web development in the CMU webapps course. With sqlite3, it is not very tailored to storing large files, however we will be keeping our processed files in a media folder on the AWS EC2 instance, as it can hold more data anyways, then we will store file references in the sqlite3 backend.
For the next week, I will begin getting our audio processing modules on the web app and being able to interact in basic ways. I will work with the team to flush out an interface protocol to know how the user interface will be sending commands to the audio processing and note scheduler.