Open joewreschnig opened 2 years ago
The wrap and level in the Pico SDK are passed as uint16_t, but the calculations in play are done with uint32_t. This leads to incorrect tones or no sound being played at all for many values. E.g. if you play(523):
play
play(523)
uint32_t wrap = clock_get_hz(clk_sys)/freq - 1; uint32_t level = (uint32_t)(wrap * (duty / 65535.0f)); // i.e. uint32_t wrap = 125000000/523 - 1; uint32_t wrap = 239004; // and so uint32_t level = (uint32_t)(239004 * (32768 / 65535.0f)); uint32_t level = 119502;
When truncated to 16 bits during passing to pwm_set_wrap and pwm_set_chan_level, results in wrap = 42396 and level = 53967, i.e. a 0% duty cycle.
pwm_set_wrap
pwm_set_chan_level
wrap = 42396
level = 53967
Instead, to handle frequencies below ~2kHz, you need to adjust the clock divider as well. E.g. the similar code in MicroPython.
The wrap and level in the Pico SDK are passed as uint16_t, but the calculations in
playare done with uint32_t. This leads to incorrect tones or no sound being played at all for many values. E.g. if youplay(523):When truncated to 16 bits during passing to
pwm_set_wrapandpwm_set_chan_level, results inwrap = 42396andlevel = 53967, i.e. a 0% duty cycle.Instead, to handle frequencies below ~2kHz, you need to adjust the clock divider as well. E.g. the similar code in MicroPython.