Never understand why a piano has so many keys? Think a single octave is more than enough? The FPGA piano allows you to practice your favorite scales or chords and even lets you listen to some of your favorite tunes while you take a break. Our piano has two different modes Piano Mode and Song mode. In Piano Mode, the user can toggle the switches to play different tones and chords from the eight notes in an octave. In Song Mode, the user can depress the buttons on the FPGA to play four different recorded sequences: scales, a simple repeating pattern, Happy Birthday, and (FPGA)Piano Man.

We undertook this project because it offers a synthesis of digital logic synthesized on an FPGA and the world of analog signals that show up in other classes. Additionally, the piano provides a fun opportunity to explore musical interactions with the FPGA and translate between the frequencies of electronics and the frequencies of hearing. Also we spent a lot of time this semester modulating clock frequencies and coordinating timing, so we wanted a final project that allowed us to demonstrate our understanding of these concepts.

Note Tones The basis of the piano’s functionality is its ability to produce a variety of square waves of different frequencies that match the tones humans associate with the keys of a piano. We accomplished this in verilog by creating a module which takes a clock divider value as a parameter. The module counts the positive edges of the 25 MHz FPGA clock signal and inverts the value of an output wire whenever the count reaches the clock divider parameter. We created instances of this module to output each of the 8 base tones we desired: C4 (262 Hz), D (294 Hz), E (330 Hz), etc., all the way to C5 (523 Hz). We later added a few extra tones that we needed for Song Mode. If the FPGA clock is altered to 50 or 100 MHz using the external jumper, the counter will increment twice or four times faster, increasing the output by one or two octaves.

Piano Mode

Song Mode

Song Data Generation