Benjamin Leverett / Mbed 2 deprecated Final_Project_2

Ben with semaphore test 1

Dependencies:   mbed mbed-rtos 4DGL-uLCD-SE SDFileSystem ATParser

Speaker.h@7:9b36eb4811eb, 2020-04-24 (annotated)

Committer:
bleverett3
Date:
Fri Apr 24 22:00:23 2020 +0000
Revision:
7:9b36eb4811eb
Parent:
2:f65d4206b47b 
Ben "change" test 1

Who changed what in which revision?

UserRevisionLine numberNew contents of line
chenchen2020 2:f65d4206b47b 1 class Speaker
chenchen2020 2:f65d4206b47b 2 {
chenchen2020 2:f65d4206b47b 3 public:
chenchen2020 2:f65d4206b47b 4 Speaker(PinName pin) : _pin(pin) {
chenchen2020 2:f65d4206b47b 5 // _pin(pin) means pass pin to the Speaker Constructor
chenchen2020 2:f65d4206b47b 6 // precompute 32 sample points on one sine wave cycle
chenchen2020 2:f65d4206b47b 7 // used for continuous sine wave output later
chenchen2020 2:f65d4206b47b 8 for(int k=0; k<32; k++) {
chenchen2020 2:f65d4206b47b 9 Analog_out_data[k] = int (65536.0 * ((1.0 + sin((float(k)/32.0*6.28318530717959)))/2.0));
chenchen2020 2:f65d4206b47b 10 // scale the sine wave to 16-bits - as needed for AnalogOut write_u16 arg
chenchen2020 2:f65d4206b47b 11 }
chenchen2020 2:f65d4206b47b 12
chenchen2020 2:f65d4206b47b 13 }
chenchen2020 2:f65d4206b47b 14 // class method to play a note based on AnalogOut class
chenchen2020 2:f65d4206b47b 15 void PlayNote(float frequency, float duration, float volume) {
chenchen2020 2:f65d4206b47b 16 // scale samples using current volume level arg
chenchen2020 2:f65d4206b47b 17 for(int k=0; k<32; k++) {
chenchen2020 2:f65d4206b47b 18 Analog_scaled_data[k] = Analog_out_data[k] * volume;
chenchen2020 2:f65d4206b47b 19 }
chenchen2020 2:f65d4206b47b 20 // reset to start of sample array
chenchen2020 2:f65d4206b47b 21 i=0;
chenchen2020 2:f65d4206b47b 22 // turn on timer interrupts to start sine wave output
chenchen2020 2:f65d4206b47b 23 Sample_Period.attach(this, &Speaker::Sample_timer_interrupt, 1.0/(frequency*32.0));
chenchen2020 2:f65d4206b47b 24 // play note for specified time
chenchen2020 2:f65d4206b47b 25 wait(duration);
chenchen2020 2:f65d4206b47b 26 // turns off timer interrupts
chenchen2020 2:f65d4206b47b 27 Sample_Period.detach();
chenchen2020 2:f65d4206b47b 28 // sets output to mid range - analog zero
chenchen2020 2:f65d4206b47b 29 this->_pin.write_u16(32768);
chenchen2020 2:f65d4206b47b 30
chenchen2020 2:f65d4206b47b 31 }
chenchen2020 2:f65d4206b47b 32 private:
chenchen2020 2:f65d4206b47b 33 // sets up specified pin for analog using AnalogOut class
chenchen2020 2:f65d4206b47b 34 AnalogOut _pin;
chenchen2020 2:f65d4206b47b 35 // set up a timer to be used for sample rate interrupts
chenchen2020 2:f65d4206b47b 36 Ticker Sample_Period;
chenchen2020 2:f65d4206b47b 37
chenchen2020 2:f65d4206b47b 38 //variables used by interrupt routine and PlayNote
chenchen2020 2:f65d4206b47b 39 volatile int i;
chenchen2020 2:f65d4206b47b 40 short unsigned Analog_out_data[32];
chenchen2020 2:f65d4206b47b 41 short unsigned Analog_scaled_data[32];
chenchen2020 2:f65d4206b47b 42
chenchen2020 2:f65d4206b47b 43 // Interrupt routine
chenchen2020 2:f65d4206b47b 44 // used to output next analog sample whenever a timer interrupt occurs
chenchen2020 2:f65d4206b47b 45 void Sample_timer_interrupt(void) {
chenchen2020 2:f65d4206b47b 46 // send next analog sample out to D to A
chenchen2020 2:f65d4206b47b 47 this->_pin.write_u16(Analog_scaled_data[i]);
chenchen2020 2:f65d4206b47b 48 // increment pointer and wrap around back to 0 at 32
chenchen2020 2:f65d4206b47b 49 i = (i+1) & 0x01F;
chenchen2020 2:f65d4206b47b 50 }
chenchen2020 2:f65d4206b47b 51 };
chenchen2020 2:f65d4206b47b 52