Hello everyone in the LPC Forums; we’re seniors in Electrical Engineering from Penn State University. Our senior design class topic was Embedded Digital Audio, and our project is based on the LPCXpresso54608 that NXP graciously provided us. Thank you for that, and also for your prompt replies to our debug posts and messages about the board before it was available to the general public. Our project, Embedded Audio Mixer, is a graphical user interface derived from DJ mixing software, where we mix or cascade different Biquad filters such as Lowpass, Notch, and PeakingEQ, and allow the user to pick their own center frequency and Q factor to create a unique listening experience.
For our project, we used the Cirrus Logic Chip, the WM8904 onboard the device, and a custom graphics library running on the LCD Touchscreen. The user selects when to start/stop the playback, pick a comfortable volume range, adjust filters type and their respective characteristics such as center frequency, dB Gain, etc., and add up to 3 filters in cascade. After the user selects the filters, we used interrupts to bring in audio data, process it and output it. This process is done in real time and therefore we limited the number of cascading filters to three.
Attached with this post is the Final Design Report detailing the project from concept to delivery. In addition, the links to our Youtube video demonstrating the project and the source code are listed below:
GitHub: https://github.com/MattPennock/Embedded-Audio-Mixer (Embeded Audio Mixer)
https://github.com/MattPennock/Biquad (Biquad Filters Standalone)
https://github.com/MattPennock/Interaction (Graphics Library Standalone)
Youtube: Team Echo- Embedded Audio Mixer Demo