Yuu Kobayashi
Nucleo F401REでFM音源を実装するやつ 外部DACとオペアンプを利用 現在はMCP4922とNJM2737
Dependencies: AOTTrigon I2CEEPROM MCP4922 AQM0802A mbed
Fork of
NuMidi401
by 
Yuu Kobayashi
NuFM401
Nucleo F401用の自作ソフトウェアMIDI音源
概要
だいたいそんなもんです。
特徴
- ブレッドボードの上で組める程度には簡単な回路構成
- 外部のDACにMCP4922を採用
- 念のためのボルテージフォロアとしてNJM2737Dを採用
- バンク用EEPROMに24FC1025を採用
- シリアル経由でMIDIデータを受信することで操作
補足
シリアル <=> MIDI のドライバにはHairless-MIDISerialをオススメします。 仮想MIDIケーブルはとりあえずMIDI Yokeで。
Diff: FMOscillator/FMOperator.cpp
- Revision:
- 13:e11380ceb460
- Parent:
- 12:7408b85fba39
- Child:
- 21:e3014c1bdf9c
diff -r 7408b85fba39 -r e11380ceb460 FMOscillator/FMOperator.cpp
--- /dev/null Thu Jan 01 00:00:00 1970 +0000
+++ b/FMOscillator/FMOperator.cpp Sat Jan 17 03:57:58 2015 +0000
@@ -0,0 +1,98 @@
+#include "FMOperator.h"
+
+static const float pi2 = 6.283185307179586476925286766559f;
+inline float getFloatRate(char cr);
+
+FMOperator::FMOperator()
+{
+ attack = 0.0f;
+ decay = 0.0f;
+ sustain = 1.0f;
+ sustainRate = 0.0f;
+ release = 0.0f;
+
+ frequencyMultiple = 1.0f;
+ totalLevel = 1.0f;
+ modulation = 0.0f;
+
+ startTime = 0.0;
+ releaseTime = 0.0;
+ baseFrequency = 1.0f;
+ feedback = 0.0f;
+ prev = 0.0f;
+ released = false;
+}
+
+FMOperator::FMOperator(Timer *tm, AOTTrigon *t)
+{
+ attack = 0.0f;
+ decay = 0.0f;
+ sustain = 0.0f;
+ sustainRate = 1.0f;
+ release = 0.0f;
+
+ frequencyMultiple = 1.0f;
+ totalLevel = 1.0f;
+ modulation = 1.0f;
+
+ tri = t;
+ master = tm;
+ startTime = 0.0;
+ releaseTime = 0.0;
+ baseFrequency = 1.0f;
+ feedback = 0.0f;
+ prev = 0.0f;
+ released = false;
+}
+
+float FMOperator::calculate(double time, float fmIn) {
+ if (startTime == 0.0) return 0.0f;
+ float pos = (pi2 * baseFrequency * frequencyMultiple);
+ double abt = master->read_us() / 1000000.0;
+ double nt = abt - startTime;
+ float e;
+ if (released) {
+ e = getEnvelopeReleaseRate(abt - releaseTime,getEnvelopeRate(nt));
+ } else {
+ e = getEnvelopeRate(nt);
+ }
+ if (feedback != 0.0f) {
+ return prev = tri->sin((float)(pos * nt) + prev * feedback) * e * totalLevel * modulation;
+ }
+ return tri->sin(fmIn + (float)(pos * nt)) * e * totalLevel * modulation;
+}
+
+void FMOperator::attackNote(float freq, double time) {
+ baseFrequency = freq;
+ startTime = time;
+ released = false;
+}
+
+void FMOperator::releaseNote(double time) {
+ releaseTime = time;
+ released = true;
+}
+
+float FMOperator::getEnvelopeRate(double reltime) {
+ //アタック・ディケイ・リリースに要する時間は
+ //127の時0s、0のとき1s
+ if (attack != 0.0f && reltime <= attack) {
+ return reltime * (1.0f / attack);
+ }
+ if (decay != 0.0f && reltime <= (attack + decay)) {
+ reltime -= attack;
+ return 1.0f - reltime * (1.0f - sustain) / (decay);
+ }
+ return (sustainRate != 0.0f) ? sustain - (reltime - decay) * (sustain / sustainRate) : sustain;
+}
+
+float FMOperator::getEnvelopeReleaseRate(double rlst,float orate) {
+ //どう考えても無音・1回も鳴らしてない・リリースなし
+ //ってどれが一番頻度高いかね
+ if (rlst >= (attack + decay + release) || release == 0.0f || startTime == 0.0) {
+ return 0;
+ } else {
+ return orate - rlst * (orate / release);
+ }
+}
+