![](/media/cache/img/default_profile.jpg.50x50_q85.jpg)
Digital Sound Synthesizer for lab 4
Dependencies: LSM9DS1_Library_cal PinDetect mbed-rtos mbed
Diff: main.cpp
- Revision:
- 0:0d977b83a68d
diff -r 000000000000 -r 0d977b83a68d main.cpp --- /dev/null Thu Jan 01 00:00:00 1970 +0000 +++ b/main.cpp Tue Mar 15 21:27:30 2016 +0000 @@ -0,0 +1,207 @@ +#include "mbed.h" +#include "rtos.h" +#include "mpr121.h" +#include "PinDetect.h" +#include "LSM9DS1.h" + +// Sound waveform synthesizer +// The program precomputes 128 data points on one wave cycle +// for triangular, sawtooth, and sine waves. These are stored +// and outout to the PWM to vary the PWM duty cycle. A very high +// PWM frequency is used and the frequency of the output soundwave +// is changed by changing the sampling rate. The program uses the +// IMU to shift frequencies, the keypad to choose center frequencies, +// the RGB LED to visually display pitch, and a pushbutton to switch between wave modes. + +#define PI 3.141592653589793238462 + +InterruptIn irq(p11); +I2C i2c1(p9,p10); +Mpr121 touchpad(&i2c1, Mpr121::ADD_VSS); +PwmOut PWM(p26); +Serial pc(USBTX,USBRX); +LSM9DS1 IMU(p28, p27, 0xD6, 0x3C); +Mutex stdio_mutex; + +PwmOut RGBLED_r(p21); +PwmOut RGBLED_g(p22); +PwmOut RGBLED_b(p23); + +PinDetect pb1(p17); +DigitalOut led1(LED1); +DigitalOut led2(LED2); +DigitalOut led3(LED3); +DigitalOut led4(LED4); + +//Global variables used by interrupt routines and threads +volatile int i=0; +volatile int j=0; +float sineInit[128]; +float sawInit[128]; +float triInit[128]; +volatile float baseFreq = 440; +float maxDeltaFreq = 200; +float maxDeltaXAxis = 15; +volatile float freq = 900; +volatile float deltaFreq = 0; +volatile float deltaXAxis = 0; +volatile float deltaXAxisOld = 0; +float frequencyScales[12] = {261.626, 293.665, 329.628, 349.228, 391.995, 440.0, + 493.883, 523.251, 587.33, 659.255, 783.991, 880}; + +enum Waveforms {sine=0,sawTooth,triangle}; +Waveforms wave = sine; + +//Samples IMU every .5 seconds and adjusts frequencies accordingly +void sample_IMU(void const *args) +{ + while(1) { + if(IMU.accelAvailable()) { + stdio_mutex.lock(); + deltaXAxisOld = deltaXAxis; + deltaXAxis = (0.0024*IMU.readAccel(X_AXIS)); //Measures difference of IMU from base value of 0 + stdio_mutex.unlock(); + } + Thread::wait(500); + } +} + +//Plays the current waveform at the current frequency +void playSineWave() { + while(j<150) { //Controls how many cycles. Plays about 3 full cycles + switch(wave) { + case sine: + PWM = (sineInit[i]); + break; + case sawTooth: + PWM = sawInit[i]; + break; + case triangle: + PWM = triInit[i]; + break; + default: + led2 = 0; + led3 = 0; + led4 = 0; + break; + } + //(1.0 + sin((float(i)*freq*6.28318530717959/(128.0))))/2.0); + // increment pointer and wrap around back to 0 at 128 + if(i>60) { + j++; + } + i = (i+1) & 0x07F; + wait_us(1000000.0/((freq+deltaFreq)*128)); + } + + //At the end of 3 cycles, reset counters + i=0; + j=0; + + int value=touchpad.read(0x00); + value +=touchpad.read(0x01)<<8; + if (value == 0) { + //Reset values if keypad is not being touched + PWM = 0; + deltaFreq = 0; + deltaXAxis = 0; + RGBLED_r = 0; + RGBLED_g = 0; + RGBLED_b = 0; + } else { + //If the keypad has a nonzero value, update the frequency and play more cycles + stdio_mutex.lock(); + float diff = (abs(deltaXAxis - deltaXAxisOld) > 2) ? deltaXAxis : deltaXAxisOld; //Makes the delta frequency resistant to noise in the IMU + stdio_mutex.unlock(); + + //Calculates delta frequency from center frequency based off of IMU accelerometer + if(abs(diff) > maxDeltaXAxis) + deltaFreq = maxDeltaFreq; + else { + deltaFreq = diff/maxDeltaXAxis*maxDeltaFreq; + } + + RGBLED_r = abs(freq-deltaFreq-220)/880; + RGBLED_g = abs(freq-220)/880; + RGBLED_b = abs(freq+deltaFreq-220)/880;; + playSineWave(); + } +} + +//Called when the touchpad is tapped +void fallInterrupt() { + int key_code=0; + int n=0; + int value=touchpad.read(0x00); + value +=touchpad.read(0x01)<<8; + for (n=0; n<12; n++) { + if (((value>>n)&0x01)==1) { + key_code=n+1; + } + } + //sets frequency based on the tapped value + freq = frequencyScales[key_code-1]; + if (value != 0) { + playSineWave(); + } +} + +//Switches the current waveform and leds +void pb1_released_callback(void){ + if (wave == triangle) { + led2 = 1; + led3 = 0; + led4 = 0; + wave = sine; + } else if (wave == sine) { + led2 = 0; + led3 = 1; + led4 = 0; + wave = sawTooth; + } else { + led2 = 0; + led3 = 0; + led4 = 1; + wave = triangle; + } +} + +int main() +{ + pc.printf("Program starting."); + PWM.period(1.0/200000.0); + led2 = 1; + led3 = 0; + led4 = 0; + + // Precompute 128 sample points on one wave cycle for three wave forms + // used for continuous wave output later + for(int k=0; k<128; k++) { + sineInit[k] = 1.0*((1.0 + sin((float(k)/128.0*2*PI)))/2.0); + sawInit[k] = (1.0 + ((-2.0*1.0/PI)*atan(cos(float(k)*PI/128.0)/sin(float(k)*PI/128.0))))/2.0; + triInit[k] = (1.0 + ((2.0*1.0/PI)*asin(sin(2.0*PI*float(k)/128.0))))/2.0; + // scale the waves from 0.0 to 1.0 - as needed for AnalogOut arg + } + + //Configure the IMU + IMU.begin(); + if (!IMU.begin()) { + pc.printf("Failed to communicate with LSM9DS1.\n"); + } + IMU.calibrate(1); + + //Configure the Push button + pb1.mode(PullUp); + wait(0.01); + pb1.attach_deasserted(&pb1_released_callback); + pb1.setSampleFrequency(); + + //Set up the I2C Touch keypad interrupt + irq.fall(&fallInterrupt); + irq.mode(PullUp); + + //And the IMU Sample thread + Thread t1(sample_IMU); + + while(1) {} +} \ No newline at end of file