Converts an RTTL ringtone into verilog and plays it back using differential PWM modulation.
Provide 12kHz clock on io_in[0], briefly hit reset io_in[1] (L->H->L) and io_out[1:0] will play a differential sound wave over piezo speaker (Bad Apple)
Piezo speaker connected across io_out[1:0]
| # | Input | Output |
|---|---|---|
| 0 | clock | piezo_speaker_p |
| 1 | reset | piezo_speaker_n |
| 2 | ||
| 3 | ||
| 4 | ||
| 5 | ||
| 6 | ||
| 7 |