From 4e99625f7cd9ccd10251c871670b286536483333 Mon Sep 17 00:00:00 2001 From: Dean Camera Date: Tue, 23 Mar 2010 10:09:49 +0000 Subject: Change over MIDIToneGenerator to use only a single channel (MIDI channel 1) due to cycle constraints. --- .../MIDIToneGenerator/MIDIToneGenerator.c | 48 ++++++---------------- 1 file changed, 12 insertions(+), 36 deletions(-) diff --git a/Projects/Incomplete/MIDIToneGenerator/MIDIToneGenerator.c b/Projects/Incomplete/MIDIToneGenerator/MIDIToneGenerator.c index 8d5cd05c9..4df37504f 100644 --- a/Projects/Incomplete/MIDIToneGenerator/MIDIToneGenerator.c +++ b/Projects/Incomplete/MIDIToneGenerator/MIDIToneGenerator.c @@ -76,14 +76,9 @@ const uint8_t SineTable[] PROGMEM = 0x4f, 0x51, 0x54, 0x57, 0x5a, 0x5d, 0x60, 0x63, 0x67, 0x6a, 0x6d, 0x70, 0x73, 0x76, 0x79, 0x7c }; -struct -{ - uint8_t Pitch; - uint8_t Velocity; - - uint8_t CurrentPos; - uint8_t ElapsedTicks; -} ChannelStates[10]; +uint8_t Pitch; +uint8_t Velocity; +uint8_t CurrentPos; /** Main program entry point. This routine contains the overall program flow, including initial * setup of all components and the main program loop. @@ -99,16 +94,16 @@ int main(void) MIDI_EventPacket_t ReceivedMIDIEvent; if (MIDI_Device_ReceiveEventPacket(&Keyboard_MIDI_Interface, &ReceivedMIDIEvent)) { - if (ReceivedMIDIEvent.Command == (MIDI_COMMAND_NOTE_ON >> 4)) + if ((ReceivedMIDIEvent.Command == (MIDI_COMMAND_NOTE_ON >> 4)) && ((ReceivedMIDIEvent.Data1 & 0x0F) == 0)) { - ChannelStates[ReceivedMIDIEvent.Data1 & 0x0F].Pitch = ReceivedMIDIEvent.Data2; - ChannelStates[ReceivedMIDIEvent.Data1 & 0x0F].Velocity = ReceivedMIDIEvent.Data3; + Pitch = ReceivedMIDIEvent.Data2; + Velocity = ReceivedMIDIEvent.Data3; LEDs_SetAllLEDs(LEDS_LED1); } - else if (ReceivedMIDIEvent.Command == (MIDI_COMMAND_NOTE_OFF >> 4)) + else if ((ReceivedMIDIEvent.Command == (MIDI_COMMAND_NOTE_OFF >> 4)) && ((ReceivedMIDIEvent.Data1 & 0x0F) == 0)) { - ChannelStates[ReceivedMIDIEvent.Data1 & 0x0F].Velocity = 0; + Velocity = 0; LEDs_SetAllLEDs(LEDS_NO_LEDS); } @@ -120,30 +115,11 @@ int main(void) /* Clear the sample reload timer */ TIFR0 |= (1 << OCF0A); - uint8_t OutputSample = 0; - - /* Loop through the channels (excluding percussion channel 10) and generate next sample */ - for (uint8_t Channel = 0; Channel < 9; Channel++) - { - /* Channel only contributes if it is not muted */ - if (ChannelStates[Channel].Velocity) - { - /* Fetch the current sample from the sine lookup table */ - uint8_t TableValue = pgm_read_byte(&SineTable[ChannelStates[Channel].CurrentPos]); + /* Fetch the current sample from the sine lookup table */ + OCR3A = Velocity ? pgm_read_byte(&SineTable[CurrentPos]) : 0; - /* Scale sample value by the velocity of the channel */ - TableValue = ((uint16_t)TableValue << 6) / ChannelStates[Channel].Velocity; - - /* Add the sample to the output waveform */ - OutputSample += TableValue; - } - - /* Calculate next sample table position for this channel */ - ChannelStates[Channel].CurrentPos += ChannelStates[Channel].Pitch; - } - - /* Output the sample to the PWM timer */ - OCR3A = OutputSample; + /* Calculate next sample table position for this channel */ + CurrentPos += (Pitch >> 1); } MIDI_Device_USBTask(&Keyboard_MIDI_Interface); -- cgit v1.2.3