This week, I worked with Rahul on integrating the Raspberry Pi with the computer’s local application. Since the computer will be sending and receiving measure numbers as points of reference for where in the piece to start playing and what part of the piece to display on the screen, I had to restructure the code so that the measure numbers were the keys in the dictionary that holds all the notes. This would make it easier for the RPi to look up which notes to play at specific times. With Rahul’s guidance, I re-implemented the scheduler to be compatible with this data structure change. Thanks to Rahul’s suggestion, I also changed the code so that the RPi loops continuously while checking the system time instead of sleeping unnecessarily as was done in the previous version. I was able to alter the code and get it back to a working implementation.
Another area I worked on was introducing the serial communication to the Raspberry Pi. As mentioned by Rahul, we did not have the required USB to UART converter that would allow us to interface with the RPi’s TX and RX pins. To avoid the extra cost and delay to our schedule that would result from purchasing an adapter, we decided to use Arduino microcontrollers that have built in serial ports. In tandem with Rahul, I experimented with using the Arduino MKRZero which has two serial ports: one between the Arduino and the computer and another to the on-board TX and RX pins. By using these two pins, and having the Arduino read the data from the USB and write to the TX/read from the RX and write back to the USB, I was able to set up the system to send and receive strings between my computer and the RPi. While one risk of this implementation is that there may be added latency, the fact that the serial communication is buffered should allow the Arduino to pass the information through at roughly the same baud rate. Tomorrow I will write a more comprehensive test using the system time to find the round trip latency between sending bytes from the computer and receiving a response from the RPi.
At the moment I am behind schedule since we have not completed the integration. However, we did anticipate that this part of the project would take more time and had incorporated slack time for it accordingly. Thus this is on schedule when considering that slack time.
Next week I will focus on further developing the serial communication. I will be meeting with Rahul to agree upon the command bytes that will be sent for various situations that are required by the application.