For this exercise split into four groups. We will be building a drum machine that comprises 3 audio instruments and a sequencer. Each group should work on a separate part and integrate them together at the end.
A hihat is produced by a small metal cymbal. It contains a lot of rich metalic harmonics. You may use FM, additive or other methods of your choice to make the instrument. Make it possible to vary the tone, and have two input triggers for a short and long decay version of the sound.
A bass/kick drum is a short low frequency pulse produced when you hit a large damped plastic skin/membrane. The sound decays from about 200Hz to about 80Hz in a short time. Add controls to vary the decay, tone and sweep of the drum.
The snare is a composition of a smaller drum than the kick and a metal wire that rattles against the skin to produce a noisy effect. The frequency of a snare is higher, around 200-400Hz. Work out a way to get the rattle of the snare using noise or other techniques. Add controls for decay and tone.
Make a drum sequencer that has 16 steps and 4 tracks. Each track should contain a number of toggle buttons to switch the instrument on or off for that step. On each step it should output a bang/trigger message for each instrument and then proceed to the next step. On the last step cycle back to the first step so that a loop plays continuously.
Connect together the above modules to create a simple drum machine. A mixer to combine the instruments at nice levels and a tempo control will complete the exercise.