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ceiborg/piano.ino

Created September 5, 2020 01:19
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Almohadón Musical (Tutorial YouTube)
Raw
piano.ino
Joe Marshall 2011
// Resonant filter based on Meeblip (meeblip.noisepages.com)
// Interrupt setup code based on code by Martin Nawrath (http://interface.khm.de/index.php/lab/experiments/arduino-dds-sinewave-generator/)
// oscillators and inline assembler optimisation by me.
//
// key input is from 8 capacitive inputs on digital input 6,7, and analog inputs 0-6
// each input is a single wire, going to something metal to touch
// (I used a bunch of big carriage bolts)
//
// sensing of this is done by getNoteKeys, using the method described at:
// http://www.arduino.cc/playground/Code/CapacitiveSensor
//
// I use assembler with an unrolled loop using 16 registers to detect this
// this makes things much more accurate than the C loop described on the link above
// as we are measuring the relevant delay in single processor cycles.
// It seems to be happy even with battery power, detecting up to 8 concurrent
// touches.
// The waves are all defined at the very top, because we are forcing them to align to 256 byte boundaries
// doing this makes the oscillator code quicker (as calculating a wave offset is just
// a matter of replacing the low byte of the address).
// Having said that, other arduino stuff probably gets loaded in here first
// because the aligned attribute seems to add a couple of hundred bytes to the code
#define TEST_PATTERN_INTRO
//#define FILTER_LPF_NONE
#define FILTER_LPF_HACK
// table of 256 sine values / one sine period / stored in flash memory
char sine256[256] __attribute__ ((aligned(256))) = {
0 , 3 , 6 , 9 , 12 , 15 , 18 , 21 , 24 , 27 , 30 , 33 , 36 , 39 , 42 , 45 ,
48 , 51 , 54 , 57 , 59 , 62 , 65 , 67 , 70 , 73 , 75 , 78 , 80 , 82 , 85 , 87 ,
89 , 91 , 94 , 96 , 98 , 100 , 102 , 103 , 105 , 107 , 108 , 110 , 112 , 113 , 114 , 116 ,
117 , 118 , 119 , 120 , 121 , 122 , 123 , 123 , 124 , 125 , 125 , 126 , 126 , 126 , 126 , 126 ,
127 , 126 , 126 , 126 , 126 , 126 , 125 , 125 , 124 , 123 , 123 , 122 , 121 , 120 , 119 , 118 ,
117 , 116 , 114 , 113 , 112 , 110 , 108 , 107 , 105 , 103 , 102 , 100 , 98 , 96 , 94 , 91 ,
89 , 87 , 85 , 82 , 80 , 78 , 75 , 73 , 70 , 67 , 65 , 62 , 59 , 57 , 54 , 51 ,
48 , 45 , 42 , 39 , 36 , 33 , 30 , 27 , 24 , 21 , 18 , 15 , 12 , 9 , 6 , 3 ,
0 , -3 , -6 , -9 , -12 , -15 , -18 , -21 , -24 , -27 , -30 , -33 , -36 , -39 , -42 , -45 ,
-48 , -51 , -54 , -57 , -59 , -62 , -65 , -67 , -70 , -73 , -75 , -78 , -80 , -82 , -85 , -87 ,
-89 , -91 , -94 , -96 , -98 , -100 , -102 , -103 , -105 , -107 , -108 , -110 , -112 , -113 , -114 , -116 ,
-117 , -118 , -119 , -120 , -121 , -122 , -123 , -123 , -124 , -125 , -125 , -126 , -126 , -126 , -126 , -126 ,
-127 , -126 , -126 , -126 , -126 , -126 , -125 , -125 , -124 , -123 , -123 , -122 , -121 , -120 , -119 , -118 ,
-117 , -116 , -114 , -113 , -112 , -110 , -108 , -107 , -105 , -103 , -102 , -100 , -98 , -96 , -94 , -91 ,
-89 , -87 , -85 , -82 , -80 , -78 , -75 , -73 , -70 , -67 , -65 , -62 , -59 , -57 , -54 , -51 ,
-48 , -45 , -42 , -39 , -36 , -33 , -30 , -27 , -24 , -21 , -18 , -15 , -12 , -9 , -6 , -3
};
char square256[256] __attribute__ ((aligned(256))) = {
127 , 127 , 127 , 127 , 127 , 127 , 127 , 127 , 127 , 127 , 127 , 127 , 127 , 127 , 127 , 127 ,
127 , 127 , 127 , 127 , 127 , 127 , 127 , 127 , 127 , 127 , 127 , 127 , 127 , 127 , 127 , 127 ,
127 , 127 , 127 , 127 , 127 , 127 , 127 , 127 , 127 , 127 , 127 , 127 , 127 , 127 , 127 , 127 ,
127 , 127 , 127 , 127 , 127 , 127 , 127 , 127 , 127 , 127 , 127 , 127 , 127 , 127 , 127 , 127 ,
127 , 127 , 127 , 127 , 127 , 127 , 127 , 127 , 127 , 127 , 127 , 127 , 127 , 127 , 127 , 127 ,
127 , 127 , 127 , 127 , 127 , 127 , 127 , 127 , 127 , 127 , 127 , 127 , 127 , 127 , 127 , 127 ,
127 , 127 , 127 , 127 , 127 , 127 , 127 , 127 , 127 , 127 , 127 , 127 , 127 , 127 , 127 , 127 ,
127 , 127 , 127 , 127 , 127 , 127 , 127 , 127 , 127 , 127 , 127 , 127 , 127 , 127 , 127 , 127 ,
-127 , -127 , -127 , -127 , -127 , -127 , -127 , -127 , -127 , -127 , -127 , -127 , -127 , -127 , -127 , -127 ,
-127 , -127 , -127 , -127 , -127 , -127 , -127 , -127 , -127 , -127 , -127 , -127 , -127 , -127 , -127 , -127 ,
-127 , -127 , -127 , -127 , -127 , -127 , -127 , -127 , -127 , -127 , -127 , -127 , -127 , -127 , -127 , -127 ,
-127 , -127 , -127 , -127 , -127 , -127 , -127 , -127 , -127 , -127 , -127 , -127 , -127 , -127 , -127 , -127 ,
-127 , -127 , -127 , -127 , -127 , -127 , -127 , -127 , -127 , -127 , -127 , -127 , -127 , -127 , -127 , -127 ,
-127 , -127 , -127 , -127 , -127 , -127 , -127 , -127 , -127 , -127 , -127 , -127 , -127 , -127 , -127 , -127 ,
-127 , -127 , -127 , -127 , -127 , -127 , -127 , -127 , -127 , -127 , -127 , -127 , -127 , -127 , -127 , -127 ,
-127 , -127 , -127 , -127 , -127 , -127 , -127 , -127 , -127 , -127 , -127 , -127 , -127 , -127 , -127 , -127
};
char triangle256[256] __attribute__ ((aligned(256))) = {
-127 , -125 , -123 , -121 , -119 , -117 , -115 , -113 , -111 , -109 , -107 , -105 , -103 , -101 , -99 , -97 ,
-95 , -93 , -91 , -89 , -87 , -85 , -83 , -81 , -79 , -77 , -75 , -73 , -71 , -69 , -67 , -65 ,
-63 , -61 , -59 , -57 , -55 , -53 , -51 , -49 , -47 , -45 , -43 , -41 , -39 , -37 , -35 , -33 ,
-31 , -29 , -27 , -25 , -23 , -21 , -19 , -17 , -15 , -13 , -11 , -9 , -7 , -5 , -3 , -1 ,
1 , 3 , 5 , 7 , 9 , 11 , 13 , 15 , 17 , 19 , 21 , 23 , 25 , 27 , 29 , 31 ,
33 , 35 , 37 , 39 , 41 , 43 , 45 , 47 , 49 , 51 , 53 , 55 , 57 , 59 , 61 , 63 ,
65 , 67 , 69 , 71 , 73 , 75 , 77 , 79 , 81 , 83 , 85 , 87 , 89 , 91 , 93 , 95 ,
97 , 99 , 101 , 103 , 105 , 107 , 109 , 111 , 113 , 115 , 117 , 119 , 121 , 123 , 125 , 127 ,
129 , 127 , 125 , 123 , 121 , 119 , 117 , 115 , 113 , 111 , 109 , 107 , 105 , 103 , 101 , 99 ,
97 , 95 , 93 , 91 , 89 , 87 , 85 , 83 , 81 , 79 , 77 , 75 , 73 , 71 , 69 , 67 ,
65 , 63 , 61 , 59 , 57 , 55 , 53 , 51 , 49 , 47 , 45 , 43 , 41 , 39 , 37 , 35 ,
33 , 31 , 29 , 27 , 25 , 23 , 21 , 19 , 17 , 15 , 13 , 11 , 9 , 7 , 5 , 3 ,
1 , -1 , -3 , -5 , -7 , -9 , -11 , -13 , -15 , -17 , -19 , -21 , -23 , -25 , -27 , -29 ,
-31 , -33 , -35 , -37 , -39 , -41 , -43 , -45 , -47 , -49 , -51 , -53 , -55 , -57 , -59 , -61 ,
-63 , -65 , -67 , -69 , -71 , -73 , -75 , -77 , -79 , -81 , -83 , -85 , -87 , -89 , -91 , -93 ,
-95 , -97 , -99 , -101 , -103 , -105 , -107 , -109 , -111 , -113 , -115 , -117 , -119 , -121 , -123 , -125
};
char sawtooth256[256] __attribute__ ((aligned(256))) = {
-127 , -127 , -126 , -125 , -124 , -123 , -122 , -121 , -120 , -119 , -118 , -117 , -116 , -115 , -114 , -113 ,
-112 , -111 , -110 , -109 , -108 , -107 , -106 , -105 , -104 , -103 , -102 , -101 , -100 , -99 , -98 , -97 ,
-96 , -95 , -94 , -93 , -92 , -91 , -90 , -89 , -88 , -87 , -86 , -85 , -84 , -83 , -82 , -81 ,
-80 , -79 , -78 , -77 , -76 , -75 , -74 , -73 , -72 , -71 , -70 , -69 , -68 , -67 , -66 , -65 ,
-64 , -63 , -62 , -61 , -60 , -59 , -58 , -57 , -56 , -55 , -54 , -53 , -52 , -51 , -50 , -49 ,
-48 , -47 , -46 , -45 , -44 , -43 , -42 , -41 , -40 , -39 , -38 , -37 , -36 , -35 , -34 , -33 ,
-32 , -31 , -30 , -29 , -28 , -27 , -26 , -25 , -24 , -23 , -22 , -21 , -20 , -19 , -18 , -17 ,
-16 , -15 , -14 , -13 , -12 , -11 , -10 , -9 , -8 , -7 , -6 , -5 , -4 , -3 , -2 , -1 ,
0 , 1 , 2 , 3 , 4 , 5 , 6 , 7 , 8 , 9 , 10 , 11 , 12 , 13 , 14 , 15 ,
16 , 17 , 18 , 19 , 20 , 21 , 22 , 23 , 24 , 25 , 26 , 27 , 28 , 29 , 30 , 31 ,
32 , 33 , 34 , 35 , 36 , 37 , 38 , 39 , 40 , 41 , 42 , 43 , 44 , 45 , 46 , 47 ,
48 , 49 , 50 , 51 , 52 , 53 , 54 , 55 , 56 , 57 , 58 , 59 , 60 , 61 , 62 , 63 ,
64 , 65 , 66 , 67 , 68 , 69 , 70 , 71 , 72 , 73 , 74 , 75 , 76 , 77 , 78 , 79 ,
80 , 81 , 82 , 83 , 84 , 85 , 86 , 87 , 88 , 89 , 90 , 91 , 92 , 93 , 94 , 95 ,
96 , 97 , 98 , 99 , 100 , 101 , 102 , 103 , 104 , 105 , 106 , 107 , 108 , 109 , 110 , 111 ,
112 , 113 , 114 , 115 , 116 , 117 , 118 , 119 , 120 , 121 , 122 , 123 , 124 , 125 , 126 , 127
};
#include "avr/pgmspace.h"
// log table for 128 filter cutoffs
unsigned char logCutoffs[128] = {0x01,0x01,0x01,0x01,0x01,0x01,0x01,0x01,0x01,0x01,0x02,0x02,0x02,0x02,0x02,0x02,0x02,0x02,0x02,0x02,0x02,0x02,0x02,0x02,0x02,0x02,0x02,0x02,0x02,0x02,0x03,0x04,0x04,0x04,0x04,0x04,0x05,0x05,0x05,0x05,0x06,0x06,0x06,0x06,0x06,0x06,0x07,0x08,0x08,0x08,0x09,0x09,0x0A,0x0A,0x0A,0x0A,0x0B,0x0C,0x0C,0x0C,0x0C,0x0D,0x0E,0x0F,0x10,0x11,0x12,0x12,0x13,0x14,0x15,0x16,0x17,0x18,0x19,0x1A,0x1B,0x1C,0x1E,0x20,0x21,0x22,0x23,0x24,0x26,0x28,0x2A,0x2C,0x2E,0x30,0x32,0x34,0x36,0x38,0x3A,0x40,0x42,0x44,0x48,0x4C,0x4F,0x52,0x55,0x58,0x5D,0x61,0x65,0x68,0x6C,0x70,0x76,0x7E,0x85,0x8A,0x90,0x96,0x9D,0xA4,0xAB,0xB0,0xBA,0xC4,0xCE,0xD8,0xE0,0xE8,0xF4,0xFF};
volatile unsigned int WAIT_curTime;
#define WAIT_UNTIL_INTERRUPT() WAIT_curTime=loopSteps; while(WAIT_curTime==loopSteps){}
#define SERIAL_OUT 0
// attack,decay are in 1/64ths per 125th of a second - ie. 1 = 0->1 in half a second
const int DECAY=3;
const int ATTACK=4;
volatile char* curWave=square256;
#define cbi(sfr, bit) (_SFR_BYTE(sfr) &= ~_BV(bit))
#define sbi(sfr, bit) (_SFR_BYTE(sfr) |= _BV(bit))
// this is supposedly the audio clock frequency - as
// you can see, measured freq may vary a bit from supposed clock frequency
// I'm not quite sure why
// const double refclk=31372.549; // =16MHz / 510
// const double refclk=31376.6; // measured
// variables used inside interrupt service declared as voilatile
// these variables allow you to keep track of time - as delay / millis etc. are
// made inactive due to interrupts being disabled.
volatile unsigned char loopSteps=0; // once per sample
volatile unsigned int loopStepsHigh=0; // once per 256 samples
// information about the current state of a single oscillator
struct oscillatorPhase
{
unsigned int phaseStep;
char volume;
unsigned int phaseAccu;
};
// the oscillators (8 of them)
struct oscillatorPhase oscillators[8];
// tword_m=pow(2,32)*dfreq/refclk; // calulate DDS new tuning word
// to get hz -> tuning word do: (pow(2,16) * frequency) / 31376.6
const unsigned int NOTE_FREQS[25]={273,289,307,325,344,365,386,409,434,460,487,516,546,579,613,650,688,729,773,819,867,919,974,1032,1093};
// thresholds for the capacitive sensing buttons
int calibrationThresholds[8]={0,0,0,0,0,0,0,0};
inline int getNoteKeys(boolean calibrate=false)
{
char PORTD_PINS=0b11000000; // (pins 6-7 - avoid pins 0,1 as they are used for serial port comms)
char PORTC_PINS=0b111111; //(analog pins 0-5)
const int MAX_LOOPS=16;
char port_values[MAX_LOOPS*2];
WAIT_UNTIL_INTERRUPT();
asm volatile (
// port D reading loop:
// DDRD &= ~(PORTD_PINS = 0x3f); // set pins 8-12 to input mode
"in %[temp],0x0a" "\n\t"
"andi %[temp],0x3f" "\n\t"
"out 0x0a,%[temp]" "\n\t"
// PORTD |= (PORTD_PINS); // set pins 8-12 pullup on
"in %[temp],0x0b" "\n\t"
"ori %[temp],0xC0" "\n\t"
"out 0x0b,%[temp]" "\n\t"
"in %0,0x09" "\n\t"
"in %1,0x09" "\n\t"
"in %2,0x09" "\n\t"
"in %3,0x09" "\n\t"
"in %4,0x09" "\n\t"
"in %5,0x09" "\n\t"
"in %6,0x09" "\n\t"
"in %7,0x09" "\n\t"
"in %8,0x09" "\n\t"
"in %9,0x09" "\n\t"
"in %10,0x09" "\n\t"
"in %11,0x09" "\n\t"
"in %12,0x09" "\n\t"
"in %13,0x09" "\n\t"
"in %14,0x09" "\n\t"
"in %15,0x09" "\n\t"
:
// outputs
"=r" (port_values[0]),
"=r" (port_values[2]),
"=r" (port_values[4]),
"=r" (port_values[6]),
"=r" (port_values[8]),
"=r" (port_values[10]),
"=r" (port_values[12]),
"=r" (port_values[14]),
"=r" (port_values[16]),
"=r" (port_values[18]),
"=r" (port_values[20]),
"=r" (port_values[22]),
"=r" (port_values[24]),
"=r" (port_values[26]),
"=r" (port_values[28]),
"=r" (port_values[30])
:[temp] "d" (0));
WAIT_UNTIL_INTERRUPT();
asm volatile (
// port C reading loop:
// DDRC &= ~(PORTC_PINS = 0xc0); // set pins 5-7 to input mode
"in %[temp],0x07" "\n\t"
"andi %[temp],0xc0" "\n\t"
"out 0x07,%[temp]" "\n\t"
// PORTC |= (PORTC_PINS); // set pins 5-7 pullup on
"in %[temp],0x08" "\n\t"
"ori %[temp],0x3F" "\n\t"
"out 0x08,%[temp]" "\n\t"
"in %0,0x06" "\n\t"
"in %1,0x06" "\n\t"
"in %2,0x06" "\n\t"
"in %3,0x06" "\n\t"
"in %4,0x06" "\n\t"
"in %5,0x06" "\n\t"
"in %6,0x06" "\n\t"
"in %7,0x06" "\n\t"
"in %8,0x06" "\n\t"
"in %9,0x06" "\n\t"
"in %10,0x06" "\n\t"
"in %11,0x06" "\n\t"
"in %12,0x06" "\n\t"
"in %13,0x06" "\n\t"
"in %14,0x06" "\n\t"
"in %15,0x06" "\n\t"
:
// outputs
"=r" (port_values[1]),
"=r" (port_values[3]),
"=r" (port_values[5]),
"=r" (port_values[7]),
"=r" (port_values[9]),
"=r" (port_values[11]),
"=r" (port_values[13]),
"=r" (port_values[15]),
"=r" (port_values[17]),
"=r" (port_values[19]),
"=r" (port_values[21]),
"=r" (port_values[23]),
"=r" (port_values[25]),
"=r" (port_values[27]),
"=r" (port_values[29]),
"=r" (port_values[31])
:[temp] "d" (0));
PORTC &= ~(PORTC_PINS); // pullup off pins 8-12
PORTD &= ~(PORTD_PINS); // pullup off pins 5-7
DDRC |= (PORTC_PINS); // discharge
DDRD |= (PORTD_PINS); // discharge
if(calibrate)
{
for(int c=0;c<8;c++)
{
for(int d=0;d<MAX_LOOPS;d++)
{
int liveNotes=((int*)port_values)[d];
liveNotes&=0x3fc0;
liveNotes>>=6;
if(liveNotes&(1<<c))
{
if(calibrationThresholds[c]<=d)
{
calibrationThresholds[c]=d+1;
}
break;
}
}
}
}
int liveNotes=0;
for(int c=0;c<8;c++)
{
int val = ((int*)port_values)[calibrationThresholds[c]+1];
val&=0x3fc0;
val>>=6;
if((val&(1<<c))==0)
{
liveNotes|=(1<<c);
}
}
return liveNotes;
}
// get capacitive touch on input 4 and output 3
// used for filter modulator
inline int getfiltermodulationtime()
{
static int running_average=0;
static int running_min=1024;
static int running_min_inc_count=0;
static boolean initialise_running_min=true;
unsigned int delayTime=0;
char PINNUM_OUT=3;
char PINNUM_IN=4;
char PIN_OUT=1<<PINNUM_OUT;
char PIN_IN=1<<PINNUM_IN;
// make sure inputs / outputs are set right
DDRD|=PIN_OUT;
DDRD&=~(PIN_IN);
WAIT_UNTIL_INTERRUPT();
PORTD|=PIN_OUT;
asm volatile (
"loopstart%=:" "\n\t"
"sbic 0x09,%[PINNUM_IN]" "\n\t"
"rjmp outloop%=" "\n\t"
"adiw %[delayTime],0x01" "\n\t"
"cpi %B[delayTime],0x02" "\n\t"
"brne loopstart%=" "\n\t"
"outloop%=:" "\n\t"
:[delayTime] "+&w" (delayTime)
:[PINNUM_IN] "I" (PINNUM_IN));
// set pin down - maybe don't bother timing, if it doesn't seem to add
// much accuracy?
WAIT_UNTIL_INTERRUPT();
PORTD&=~PIN_OUT;
asm(
"loopstart%=:" "\n\t"
"sbis 0x09,%[PINNUM_IN]" "\n\t"
"rjmp outloop%=" "\n\t"
"adiw %[delayTime],0x01" "\n\t"
"cpi %B[delayTime],0x02" "\n\t"
"brne loopstart%=" "\n\t"
"outloop%=:" "\n\t"
:[delayTime] "+&w" (delayTime)
:[PINNUM_IN] "I" (PINNUM_IN));
running_average=(running_average-(running_average>>4))+(delayTime>>4);
running_min_inc_count++;
if(running_min_inc_count==255)
{
if(initialise_running_min)
{
running_min=running_average;
running_min_inc_count=0;
initialise_running_min=false;
}else{
running_min_inc_count=0;
running_min++;
}
}
if(running_average<running_min)
{
running_min=running_average;
}
int touchVal=running_average-running_min;
if(touchVal>15)
{
touchVal-=15;
if(touchVal>99)
{
touchVal=99;
}
}else{
touchVal=0;
}
return touchVal;
}
// get capacitive touch on input 5 and output 3
// used for pitch bend
inline int getpitchbendtime()
{
static int running_average=0;
static int running_min=1024;
static int running_min_inc_count=0;
static boolean initialise_running_min=true;
unsigned int delayTime=0;
char PINNUM_OUT=3;
char PINNUM_IN=5;
char PIN_OUT=1<<PINNUM_OUT;
char PIN_IN=1<<PINNUM_IN;
// make sure inputs / outputs are set right
DDRD|=PIN_OUT;
DDRD&=~(PIN_IN);
WAIT_UNTIL_INTERRUPT();
PORTD|=PIN_OUT;
asm volatile (
"loopstart%=:" "\n\t"
"sbic 0x09,%[PINNUM_IN]" "\n\t"
"rjmp outloop%=" "\n\t"
"adiw %[delayTime],0x01" "\n\t"
"cpi %B[delayTime],0x02" "\n\t"
"brne loopstart%=" "\n\t"
"outloop%=:" "\n\t"
:[delayTime] "+&w" (delayTime)
:[PINNUM_IN] "I" (PINNUM_IN));
// set pin down - maybe don't bother timing, if it doesn't seem to add
// much accuracy?
WAIT_UNTIL_INTERRUPT();
PORTD&=~PIN_OUT;
asm(
"loopstart%=:" "\n\t"
"sbis 0x09,%[PINNUM_IN]" "\n\t"
"rjmp outloop%=" "\n\t"
"adiw %[delayTime],0x01" "\n\t"
"cpi %B[delayTime],0x02" "\n\t"
"brne loopstart%=" "\n\t"
"outloop%=:" "\n\t"
:[delayTime] "+&w" (delayTime)
:[PINNUM_IN] "I" (PINNUM_IN));
running_average=(running_average-(running_average>>4))+(delayTime>>4);
running_min_inc_count++;
if(running_min_inc_count==255)
{
if(initialise_running_min)
{
running_min=running_average;
running_min_inc_count=0;
initialise_running_min=false;
}else{
running_min_inc_count=0;
running_min++;
}
}
if(running_average<running_min)
{
running_min=running_average;
}
int touchVal=running_average-running_min;
if(touchVal>15)
{
touchVal-=15;
if(touchVal>99)
{
touchVal=99;
}
}else{
touchVal=0;
}
return touchVal;
}
unsigned int pitchBendTable[201]={241, 241, 241, 242, 242, 242, 242, 242, 242, 242, 243, 243, 243, 243, 243, 243, 243, 244, 244, 244, 244, 244, 244, 244, 245, 245, 245, 245, 245, 245, 245, 246, 246, 246, 246, 246, 246, 246, 247, 247, 247, 247, 247, 247, 247, 248, 248, 248, 248, 248, 248, 248, 249, 249, 249, 249, 249, 249, 249, 250, 250, 250, 250, 250, 250, 250, 251, 251, 251, 251, 251, 251, 251, 252, 252, 252, 252, 252, 252, 253, 253, 253, 253, 253, 253, 253, 254, 254, 254, 254, 254, 254, 254, 255, 255, 255, 255, 255, 255, 256,
256,256, 256, 256, 256, 256, 256, 256, 257, 257, 257, 257, 257, 257, 257, 258, 258, 258, 258, 258, 258, 259, 259, 259, 259, 259, 259, 259, 260, 260, 260, 260, 260, 260, 260, 261, 261, 261, 261, 261, 261, 262, 262, 262, 262, 262, 262, 262, 263, 263, 263, 263, 263, 263, 264, 264, 264, 264, 264, 264, 264, 265, 265, 265, 265, 265, 265, 266, 266, 266, 266, 266, 266, 266, 267, 267, 267, 267, 267, 267, 268, 268, 268, 268, 268, 268, 269, 269, 269, 269, 269, 269, 269, 270, 270, 270, 270, 270, 270, 271, 271};
void setupNoteFrequencies(int baseNote,int pitchBendVal /*-100 -> 100*/)
{
oscillators[0].phaseStep=NOTE_FREQS[baseNote];
oscillators[1].phaseStep=NOTE_FREQS[baseNote+2];
oscillators[2].phaseStep=NOTE_FREQS[baseNote+4];
oscillators[3].phaseStep=NOTE_FREQS[baseNote+5];
oscillators[4].phaseStep=NOTE_FREQS[baseNote+7];
oscillators[5].phaseStep=NOTE_FREQS[baseNote+9];
oscillators[6].phaseStep=NOTE_FREQS[baseNote+11];
oscillators[7].phaseStep=NOTE_FREQS[baseNote+12];
if(pitchBendVal<-99)
{
pitchBendVal=-99;
}else if(pitchBendVal>99)
{
pitchBendVal=99;
}
// Serial.print("*");
// Serial.print(pitchBendVal);
unsigned int pitchBendMultiplier=pitchBendTable[pitchBendVal+100];
// Serial.print(":");
// Serial.print(pitchBendMultiplier);
for(int c=0;c<8;c++)
{
// multiply 2 16 bit numbers together and shift 8 without precision loss
// requires assembler really
volatile unsigned char zeroReg=0;
volatile unsigned int multipliedCounter=oscillators[c].phaseStep;
asm volatile
(
// high bytes mult together = high byte
"ldi %A[outVal],0" "\n\t"
"mul %B[phaseStep],%B[pitchBend]" "\n\t"
"mov %B[outVal],r0" "\n\t"
// ignore overflow into r1 (should never overflow)
// low byte * high byte -> both bytes
"mul %A[phaseStep],%B[pitchBend]" "\n\t"
"add %A[outVal],r0" "\n\t"
// carry into high byte
"adc %B[outVal],r1" "\n\t"
// high byte* low byte -> both bytes
"mul %B[phaseStep],%A[pitchBend]" "\n\t"
"add %A[outVal],r0" "\n\t"
// carry into high byte
"adc %B[outVal],r1" "\n\t"
// low byte * low byte -> round
"mul %A[phaseStep],%A[pitchBend]" "\n\t"
// the adc below is to round up based on high bit of low*low:
"adc %A[outVal],r1" "\n\t"
"adc %B[outVal],%[ZERO]" "\n\t"
"clr r1" "\n\t"
:[outVal] "=&d" (multipliedCounter)
:[phaseStep] "d" (oscillators[c].phaseStep),[pitchBend] "d"( pitchBendMultiplier),[ZERO] "d" (zeroReg)
:"r1","r0"
);
oscillators[c].phaseStep=multipliedCounter;
}
// Serial.print(":");
// Serial.print(NOTE_FREQS[baseNote]);
// Serial.print(":");
// Serial.println(oscillators[0].phaseStep);
}
void setup()
{
Serial.begin(9600); // connect to the serial port
#ifndef FILTER_LPF_NONE
setFilter(127, 0);
#endif
pinMode(11, OUTPUT); // pin11= PWM output / frequency output
setupNoteFrequencies(12,0);
for(int c=0;c<8;c++)
{
oscillators[c].volume=0;
}
Setup_timer2();
// disable interrupts to avoid timing distortion
cbi (TIMSK0,TOIE0); // disable Timer0 !!! delay() is now not available
sbi (TIMSK2,TOIE2); // enable Timer2 Interrupt
// calibrate the unpressed key values
for(int x=0;x<1024;x++)
{
getNoteKeys(true);
int steps=loopSteps;
WAIT_UNTIL_INTERRUPT();
// int afterSteps=loopSteps;
// Serial.println(afterSteps-steps);
}
// test pattern intro
#ifdef TEST_PATTERN_INTRO
int filtValue=255;
byte notes[]={0x1,0x4,0x10,0x80,0x80,0x80,0x1,0x2,0x4,0x8,0x10,0x20,0x40,0x80,0x40,0x20,0x10,0x8,0x4,0x2,0x1,0x1,0x1,0x00,0x00,0x1,0x1,0x1,0x1,0x00,0x00,0x5,0x5,0x5,0x5,0x00,0x00,0x15,0x15,0x15,0x15,0x15,0x00,0x00,0x95,0x95,0x95,0x95,0x95,0x95,0x00};
for(int note=0;note<sizeof(notes)/sizeof(byte);note++)
{
int noteCount=0;
for(int c=0;c<8;c++)
{
if(notes[note]&(1<<c))
{
noteCount+=1;
}
}
for(int c=0;c<8;c++)
{
if(notes[note]&(1<<c))
{
oscillators[c].volume=63/noteCount;
}else
{
oscillators[c].volume=0;
}
}
for(int c=0;c<50;c++)
{
// might as well keep calibrating here
// nb: each calibration loop = at least 1 interrupt
getNoteKeys(true);
#ifndef FILTER_LPF_NONE
setFilter(127-c, 64);
#endif
}
}
#else
// just beep to show calibration is done
oscillators[0].volume=63;
for(int c=0;c<20;c++)
{
WAIT_UNTIL_INTERRUPT();
}
oscillators[0].volume=63;
#endif
Serial.println("Calibrations:");
for(int c=0;c<8;c++)
{
Serial.print(c);
Serial.print(":");
Serial.println(calibrationThresholds[c]);
}
}
void loop()
{
// we keep a list of 'raw' volumes - and turn down the volume if a chord is taking >64 volume total
// this is to allow chording without reducing the volume of single notes
int rawVolumes[8]={0,0,0,0,0,0,0,0};
int curNote=0;
unsigned int filterSweep=64;
const int MIN_SWEEP=64;
const int MAX_SWEEP=127;
const int SWEEP_SPEED=3;
int sweepDir=SWEEP_SPEED;
unsigned int lastStep=loopStepsHigh;
unsigned curStep=loopStepsHigh;
while(1)
{
lastStep=curStep;
curStep=loopStepsHigh;
// NOTE: timers do not work in this code (interrupts disabled / speeds changed), so don't even think about calling: delay(), millis / micros etc.
// each loopstep is roughly 31250 / second
// this main loop will get called once every 3 or 4 samples if the serial output is turned off, maybe slower otherwise
int liveNotes=getNoteKeys();
// we are right after an interrupt (as loopStep has just been incremented)
// so we should have enough time to do the capacitative key checks
if(lastStep!=curStep)
{
int totalVolume=0;
for(int c=0;c<8;c++)
{
if((liveNotes&(1<<c))==0)
{
rawVolumes[c]-=DECAY*(curStep-lastStep);
if(rawVolumes[c]<0)rawVolumes[c]=0;
if(SERIAL_OUT)Serial.print(".");
}
else
{
rawVolumes[c]+=ATTACK*(curStep-lastStep);
if(rawVolumes[c]>63)rawVolumes[c]=63;
if(SERIAL_OUT)Serial.print(c);
}
totalVolume+=rawVolumes[c];
}
WAIT_UNTIL_INTERRUPT();
if( totalVolume<64 )
{
for(int c=0;c<8;c++)
{
oscillators[c].volume=rawVolumes[c];
}
}else
{
// total volume too much, scale down to avoid clipping
for(int c=0;c<8;c++)
{
oscillators[c].volume=(rawVolumes[c]*63)/totalVolume;
}
}
}
if(SERIAL_OUT)Serial.println("");
#ifndef FILTER_LPF_NONE
/* if(liveNotes==0)
{
filterSweep=64;
sweepDir=SWEEP_SPEED;
}
filterSweep+=sweepDir;
if(filterSweep>=MAX_SWEEP)
{
filterSweep=MAX_SWEEP;
sweepDir=-sweepDir;
}
else if (filterSweep<=MIN_SWEEP)
{
sweepDir=-sweepDir;
filterSweep=MIN_SWEEP;
}*/
// Serial.println((int)filterValue);
// filterSweep=127-(getpitchbendtime()>>1);
WAIT_UNTIL_INTERRUPT();
setFilter(150-(getfiltermodulationtime()),220);
#endif
WAIT_UNTIL_INTERRUPT();
setupNoteFrequencies(12,-getpitchbendtime());
// we are right after an interrupt again (as loopStep has just been incremented)
// so we should have enough time to check the pitch bend capacitance without going over another sample, timing is quite important here
// need to balance using a big enough resistor to get decent sensing distance with taking too long to sample
// check the pitch bend input
}
}
//******************************************************************
// timer2 setup
// set prscaler to 1, PWM mode to phase correct PWM, 16000000/510 = 31372.55 Hz clock
void Setup_timer2() {
// Timer2 Clock Prescaler to : 1
sbi (TCCR2B, CS20);
cbi (TCCR2B, CS21);
cbi (TCCR2B, CS22);
// Timer2 PWM Mode set to Phase Correct PWM
cbi (TCCR2A, COM2A0); // clear Compare Match
sbi (TCCR2A, COM2A1);
sbi (TCCR2A, WGM20); // Mode 1 / Phase Correct PWM
cbi (TCCR2A, WGM21);
cbi (TCCR2B, WGM22);
}
#ifdef FILTER_LPF_BIQUAD
char filtValueA1=0,filtValueA2=0,filtValueA3=0,filtValueB1=0,filtValueB2=0;
volatile unsigned char filtCoeffA1=255;
volatile char filtCoeffB1=127;
volatile unsigned char filtCoeffB2=255;
#endif
#ifdef FILTER_LPF_HACK
// hacked low pass filter - 2 pole resonant -
// a += f*((in-a)+ q*(a-b)
// b+= f* (a-b)
int filterA=0;
int filterB=0;
unsigned char filterQ=0;
unsigned char filterF=255;
inline void setFilterRaw(unsigned char filterF, unsigned char resonance)
{
unsigned char tempReg=0,tempReg2=0;
asm volatile("ldi %[tempReg], 0xff" "\n\t"
"sub %[tempReg],%[filtF] " "\n\t"
"lsr %[tempReg]" "\n\t"
"ldi %[tempReg2],0x04" "\n\t"
"add %[tempReg],%[tempReg2]" "\n\t"
"sub %[reso],%[tempReg]" "\n\t"
"brcc Res_Overflow%=" "\n\t"
"ldi %[reso],0x00" "\n\t"
"Res_Overflow%=:" "\n\t"
"mov %[filtQ],%[reso]" "\n\t"
:[tempReg] "=&d" (tempReg),[tempReg2] "=&d" (tempReg2),[filtQ] "=&d" (filterQ): [reso] "d" (resonance), [filtF] "d" (filterF) );
}
inline void setFilter(unsigned char f, unsigned char resonance)
{
if(f>127)f=127;
filterF=logCutoffs[f];
setFilterRaw(filterF,resonance);
}
#endif
#define HIBYTE(__x) ((char)(((unsigned int)__x)>>8))
#define LOBYTE(__x) ((char)(((unsigned int)__x)&0xff))
// oscillator main loop (increment wavetable pointer, and add it to the output registers)
// 13 instructions - should take 14 processor cycles according to the datasheet
// in theory I think this means that each oscillator should take 1.5% of cpu
// (plus a constant overhead for interrupt calls etc.)
// Note: this used to do all the stepvolume loads near the start, but they are now interleaved in the
// code, this is because ldd (load with offset) takes 2 instructions,
// versus ld,+1 (load with post increment) and st,+1 which are 1 instruction - we can do this because:
//
// a)the step (which doesn't need to be stored back) is in memory before the
// phase accumulator (which does need to be stored back once the step is added
//
// b)the phase assumulator is stored in low byte, high byte order, meaning that we
// can add the first bytes together, then store that byte incrementing the pointer,
// then load the high byte, add the high bytes together and store incrementing the pointer
//
// I think this is the minimum number of operations possible to code this oscillator in, because
// 1)There are 6 load operations required (to load stepHigh/Low,phaseH/L,volume, and the value from the wave)
// 2)There are 2 add operations required to add to the phase accumulator
// 3)There are 2 store operations required to save the phase accumulator
// 4)There is 1 multiply (2 instruction cycles) required to do the volume
// 5)There are 2 add operations required to add to the final output
//
// 6+2+2+2+2 = 14 instruction cycles
#define OSCILLATOR_ASM \
/* load phase step and volume*/ \
"ld %A[tempStep],%a[stepVolume]+" "\n\t" \
"ld %B[tempStep],%a[stepVolume]+" "\n\t" \
"ld %[tempVolume],%a[stepVolume]+" "\n\t" \
/* load phase accumulator - high byte goes straight*/ \
/* into the wave lookup array (wave is on 256 byte boundary*/ \
/* so we can do this without any adds */ \
/* Do the phase adds in between the two loads, as load with offset is slower than
just a normal load
*/\
"ld %A[tempPhaseLow],%a[stepVolume]" "\n\t" \
/* add phase step low */ \
"add %[tempPhaseLow],%A[tempStep]" "\n\t"\
/* store phase accumulator low */ \
"st %a[stepVolume]+,%[tempPhaseLow]" "\n\t" \
/* load phase accumulator high*/\
"ld %A[waveBase],%a[stepVolume]" "\n\t" \
/* add phase step high - with carry from the add above */\
"adc %A[waveBase],%B[tempStep]" "\n\t"\
/* store phase step high */\
"st %a[stepVolume]+,%A[waveBase]" "\n\t" \
/* now lookup from the wave - high byte = wave pointer, low byte=offset*/ \
"ld %[tempPhaseLow],%a[waveBase]" "\n\t" \
/* now multiply by volume*/ \
"muls %[tempPhaseLow],%[tempVolume]" "\n\t" \
/* r0 now contains a sample - add it to output value*/ \
"add %A[outValue],r0" "\n\t" \
"adc %B[outValue],r1" "\n\t" \
/* go to next oscillator - stepVolume is pointing at next*/ \
/* oscillator already */ \
//******************************************************************
// Timer2 Interrupt Service at 31372,550 KHz = 32uSec
// this is the timebase REFCLOCK for the DDS generator
// FOUT = (M (REFCLK)) / (2 exp 32)
// runtime : ?
ISR(TIMER2_OVF_vect) {
// now set up the next value
// this loop takes roughly 172 cycles (214 including the push/pops) - we have 510, so roughly 50% of the processor going spare for non-audio tasks
// the low pass filter also takes some cycles
int outValue;
// pointers:
// X = oscillator phase accumulator
// Y = oscillator step and volume
// Z = wave pos - needs to add to base
int tempStep=0;
char tempPhaseLow=0,tempVolume=0;
int tempWaveBase=0;
asm volatile (
"ldi %A[outValue],0" "\n\t"
"ldi %B[outValue],0" "\n\t"
// oscillator 0
// uncomment the code below to check
// that registers aren't getting double assigned
/* "lds %A[outValue],0x00" "\n\t"
"lds %B[outValue],0x01" "\n\t"
"lds %A[tempPhaseLow],0x02" "\n\t"
// "lds %B[tempPhase],0x03" "\n\t"
"lds %A[tempStep],0x04" "\n\t"
"lds %B[tempStep],0x05" "\n\t"
"lds %[tempVolume],0x06" "\n\t"
"lds %[ZERO],0x07" "\n\t"
"lds %A[tempWaveBase],0x08" "\n\t"
"lds %B[tempWaveBase],0x09" "\n\t"
"lds %A[phaseAccu],0x0a" "\n\t"
"lds %B[phaseAccu],0x0b" "\n\t"
"lds %A[stepVolume],0x0c" "\n\t"
"lds %B[stepVolume],0x0d" "\n\t"
"lds %A[waveBase],0x0e" "\n\t"
"lds %B[waveBase],0x0f" "\n\t"*/
OSCILLATOR_ASM
OSCILLATOR_ASM
OSCILLATOR_ASM
OSCILLATOR_ASM
OSCILLATOR_ASM
OSCILLATOR_ASM
OSCILLATOR_ASM
OSCILLATOR_ASM
:
// outputs
[tempPhaseLow] "=&d" (tempPhaseLow),
[tempStep] "=&d" (tempStep),
[tempVolume] "=&d" (tempVolume),
[outValue] "=&d" (outValue)
:
// inputs
[stepVolume] "y" (&oscillators[0].phaseStep),
[waveBase] "z" (256*(((unsigned int)curWave)>>8))
:
// other registers we clobber (by doing multiplications)
"r1"
);
// at this point outValue = oscillator value
// it is currently maxed to full volume / 4
// to allow some headroom for filtering
#ifdef FILTER_LPF_HACK
// a low pass filter based on the one from MeeBlip (http://meeblip.noisepages.com)
// a += f*((in-a)+ q*(a-b)
// b+= f* (a-b)
// outValue>>=3;
// started at 4700
// 4686
int tempReg,tempReg2=0;
unsigned char zeroRegFilt=0;
// de-volatilisati
unsigned char filtF=filterF;
unsigned char filtQ=filterQ;
asm volatile(
"sub %A[outVal],%A[filtA]" "\n\t"
"sbc %B[outVal],%B[filtA]" "\n\t"
"brvc No_overflow1%=" "\n\t"
"ldi %A[outVal],0b00000001" "\n\t"
"ldi %B[outVal],0b10000000" "\n\t"
"No_overflow1%=:" "\n\t"
// outVal = (in - filtA)
"mov %A[tempReg],%A[filtA]" "\n\t"
"mov %B[tempReg],%B[filtA]" "\n\t"
"sub %A[tempReg],%A[filtB]" "\n\t"
"sbc %B[tempReg],%B[filtB]" "\n\t"
"brvc No_overflow3%=" "\n\t"
"ldi %A[tempReg],0b00000001" "\n\t"
"ldi %B[tempReg],0b10000000" "\n\t"
"No_overflow3%=:" "\n\t"
// tempReg = (a-b)
"mulsu %B[tempReg],%[filtQ]" "\n\t"
"movw %A[tempReg2],r0" "\n\t"
// tempReg2 = (HIBYTE(a-b))*Q
"mul %A[tempReg],%[filtQ]" "\n\t"
"add %A[tempReg2],r1" "\n\t"
"adc %B[tempReg2],%[ZERO]" "\n\t"
"rol r0" "\n\t"
"brcc No_Round1%=" "\n\t"
"inc %A[tempReg2]" "\n\t"
"No_Round1%=:" "\n\t"
// at this point tempReg2 = (a-b)*Q (shifted appropriately and rounded)
// "clc" "\n\t"
"lsl %A[tempReg2]" "\n\t"
"rol %B[tempReg2]" "\n\t"
// "clc" "\n\t"
"lsl %A[tempReg2]" "\n\t"
"rol %B[tempReg2]" "\n\t"
// tempReg2 = (a-b)*Q*4
"add %A[outVal],%A[tempReg2]" "\n\t"
"adc %B[outVal],%B[tempReg2]" "\n\t"
"brvc No_overflow4%=" "\n\t"
"ldi %A[outVal],0b11111111" "\n\t"
"ldi %B[outVal],0b01111111" "\n\t"
"No_overflow4%=:" "\n\t"
// outVal = ((in-a) + (a-b)*(Q>>8)*4) - clipped etc
"mulsu %B[outVal],%[filtF]" "\n\t"
"movw %A[tempReg],r0" "\n\t"
"mul %A[outVal],%[filtF]" "\n\t"
"add %A[tempReg],r1" "\n\t"
"adc %B[tempReg],%[ZERO]" "\n\t"
"rol r0" "\n\t"
"brcc No_Round2%=" "\n\t"
"inc %A[tempReg]" "\n\t"
// tempReg = f* ((in-a) + (a-b)*(Q>>8)*4)
"No_Round2%=:" "\n\t"
"add %A[filtA],%A[tempReg]" "\n\t"
"adc %B[filtA],%B[tempReg]" "\n\t"
// A= A+ f* ((in-a) + (a-b)*(Q>>8)*4)
"brvc No_overflow5%=" "\n\t"
"ldi %A[outVal],0b11111111" "\n\t"
"ldi %B[outVal],0b01111111" "\n\t"
"No_overflow5%=:" "\n\t"
// now calculate B= f* (a - b)
"mov %A[tempReg],%A[filtA]" "\n\t"
"mov %B[tempReg],%B[filtA]" "\n\t"
"sub %A[tempReg],%A[filtB]" "\n\t"
"sbc %B[tempReg],%B[filtB]" "\n\t"
"brvc No_overflow6%=" "\n\t"
"ldi %A[tempReg],0b00000001" "\n\t"
"ldi %B[tempReg],0b10000000" "\n\t"
"No_overflow6%=:" "\n\t"
// tempReg = (a-b)
"mulsu %B[tempReg],%[filtF]" "\n\t"
"movw %A[tempReg2],r0" "\n\t"
"mul %A[tempReg],%[filtF]" "\n\t"
"add %A[tempReg2],r1" "\n\t"
"adc %B[tempReg2],%[ZERO]" "\n\t"
// tempReg2 = f*(a-b)
"add %A[filtB],%A[tempReg2]" "\n\t"
"adc %B[filtB],%B[tempReg2]" "\n\t"
"brvc No_overflow7%=" "\n\t"
"ldi %A[filtB],0b11111111" "\n\t"
"ldi %B[filtB],0b01111111" "\n\t"
"No_overflow7%=:" "\n\t"
// now b= b+f*(a-b)
"mov %A[outVal],%A[filtB]" "\n\t"
"mov %B[outVal],%B[filtB]" "\n\t"
// multiply outval by 4 and clip
"add %A[outVal],%A[filtB]" "\n\t"
"adc %B[outVal],%B[filtB]" "\n\t"
"brbs 3, Overflow_End%=" "\n\t"
"add %A[outVal],%A[filtB]" "\n\t"
"adc %B[outVal],%B[filtB]" "\n\t"
"brbs 3, Overflow_End%=" "\n\t"
"add %A[outVal],%A[filtB]" "\n\t"
"adc %B[outVal],%B[filtB]" "\n\t"
"brbs 3, Overflow_End%=" "\n\t"
"rjmp No_overflow%=" "\n\t"
"Overflow_End%=:" "\n\t"
"brbs 2,Overflow_High%=" "\n\t"
"ldi %A[outVal],0b00000001" "\n\t"
"ldi %B[outVal],0b10000000" "\n\t"
"rjmp No_overflow%=" "\n\t"
"Overflow_High%=:" "\n\t"
"ldi %A[outVal],0b11111111" "\n\t"
"ldi %B[outVal],0b01111111" "\n\t"
"No_overflow%=:" "\n\t"
//char valOut=((unsigned int)(outValue))>>8;
//valOut+=128;
// OCR2A=(byte)valOut;
"subi %B[outVal],0x80" "\n\t"
"sts 0x00b3,%B[outVal]" "\n\t"
// uncomment the lines below to see the register allocations
/*
"lds %A[filtA],0x01" "\n\t"
"lds %B[filtA],0x02" "\n\t"
"lds %A[filtB],0x03" "\n\t"
"lds %B[filtB],0x04" "\n\t"
"lds %[filtQ],0x05" "\n\t"
"lds %[filtF],0x06" "\n\t"
"lds %A[outVal],0x07" "\n\t"
"lds %B[outVal],0x08" "\n\t"
"lds %A[tempReg],0x09" "\n\t"
"lds %B[tempReg],0x0a" "\n\t"
"lds %A[tempReg2],0x0b" "\n\t"
"lds %B[tempReg2],0x0c" "\n\t"
"lds %[ZERO],0x0d" "\n\t"*/
:
// outputs / read/write arguments
[filtA] "+&w" (filterA),
[filtB] "+&w" (filterB),
[tempReg] "=&a" (tempReg),
[tempReg2] "=&d" (tempReg2)
:
[filtQ] "a" (filtQ),
[filtF] "a" (filtF),
[outVal] "a" (outValue),
[ZERO] "d" (zeroRegFilt)
// inputs
: "r1");
#endif
// output is done in the filter assembler code if filters are on
// otherwise we output it by hand here
#ifdef FILTER_LPF_NONE
// full gain
outValue*=4;
// at this point, outValue is a 16 bit signed version of what we want ie. 0 -> 32767, then -32768 -> -1 (0xffff)
// we want 0->32767 to go to 32768-65535 and -32768 -> -1 to go to 0-32767, then we want only the top byte
// take top byte, then add 128, then cast to unsigned. The (unsigned int) in the below is to avoid having to shift (ie.just takes top byte)
char valOut=((unsigned int)(outValue))>>8;
valOut+=128;
OCR2A=(byte)valOut;
#endif
// increment loop step counter (and high counter)
// these are used because we stop the timer
// interrupt running, so have no other way to tell time
// this asm is probably not really needed, but it does save about 10 instructions
// because the variables have to be volatile
asm(
"inc %[loopSteps]" "\n\t"
"brbc 1,loopend%=" "\n\t"
"inc %A[loopStepsHigh]" "\n\t"
"brbc 1,loopend%=" "\n\t"
"inc %B[loopStepsHigh]" "\n\t"
"loopend%=:" "\n\t"
:[loopSteps] "+a" (loopSteps),[loopStepsHigh] "+a" (loopStepsHigh):);
}
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