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@@ -81,6 +81,7 @@ bool inited = false;
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audio_config_t audio_config;
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+uint16_t envelope_index = 0;
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void audio_toggle(void) {
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audio_config.enable ^= 1;
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@@ -298,6 +299,26 @@ float vibrato(float average_freq) {
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#endif
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+float envelope(float f) {
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+ uint16_t compensated_index = (uint16_t)((float)envelope_index * (880.0 / f));
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+ switch (compensated_index) {
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+ case 0:
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+ note_timbre = TIMBRE_50;
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+ break;
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+ case 20:
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+ note_timbre = TIMBRE_25;
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+ break;
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+ case 32:
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+ note_timbre = TIMBRE_12;
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+ break;
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+ case 40 ... 60:
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+ f = f / 2;
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+ note_timbre = TIMBRE_50;
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+ break;
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+ }
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+ return f;
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+}
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+
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ISR(TIMER3_COMPA_vect) {
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if (note) {
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#ifdef PWM_AUDIO
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@@ -387,6 +408,12 @@ ISR(TIMER3_COMPA_vect) {
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freq = frequency;
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}
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}
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+
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+ if (envelope_index < 65535) {
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+ envelope_index++;
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+ }
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+ freq = envelope(freq);
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+
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ICR3 = (int)(((double)F_CPU) / (freq * CPU_PRESCALER)); // Set max to the period
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OCR3A = (int)((((double)F_CPU) / (freq * CPU_PRESCALER)) * note_timbre); // Set compare to half the period
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}
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@@ -495,6 +522,7 @@ if (audio_config.enable && voices < 8) {
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if (notes)
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stop_all_notes();
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note = true;
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+ envelope_index = 0;
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#ifdef PWM_AUDIO
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freq = freq / SAMPLE_RATE;
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#endif
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