correct sampling rate (~29 pwm loops)

audio.c

@@ -0,0 +1,65 @@
+#include <stdint.h>
+#include <stdbool.h>
+#include "driverlib/pwm.h"
+#include "driverlib/sysctl.h"
+#include "driverlib/gpio.h"
+#include "driverlib/timer.h"
+#include "driverlib/pin_map.h"
+#include "inc/tm4c1294ncpdt.h"
+#include "driverlib/interrupt.h"
+#include "inc/hw_types.h"
+#include "inc/hw_memmap.h"
+#include "driverlib/fpu.h"
+#include <math.h>
+#include "driverlib/pwm.h"
+#include <stdlib.h>
+#include "audio_waveform.h"
+#include "frequency.h"
+
+#define AUDIO_PWM_PERIOD 258
+
+uint32_t gSamplingRateDivider = 29; // sampling rate divider
+
+void configure_audio() {
+  // configure M0PWM2, at GPIO PF2, BoosterPack 1 header C1 pin 2
+  SysCtlPeripheralEnable(SYSCTL_PERIPH_GPIOG);
+  GPIOPinTypePWM(GPIO_PORTG_BASE, GPIO_PIN_1);
+  GPIOPinConfigure(GPIO_PG1_M0PWM5);
+  GPIOPadConfigSet(GPIO_PORTG_BASE, GPIO_PIN_1, GPIO_STRENGTH_2MA,
+                   GPIO_PIN_TYPE_STD);
+  // configure the PWM0 peripheral, gen 2, outputs 5
+  SysCtlPeripheralEnable(SYSCTL_PERIPH_PWM0);
+  // use system clock without division
+  PWMClockSet(PWM0_BASE, PWM_SYSCLK_DIV_1);
+  PWMGenConfigure(PWM0_BASE, PWM_GEN_2,
+                  PWM_GEN_MODE_DOWN | PWM_GEN_MODE_NO_SYNC);
+
+  PWMGenPeriodSet(PWM0_BASE, PWM_GEN_2,
+                  AUDIO_PWM_PERIOD);
+  PWMPulseWidthSet(PWM0_BASE, PWM_OUT_5,
+                   roundf((float)AUDIO_PWM_PERIOD * 0.5f));
+
+  gSamplingRateDivider =  gSystemClock / AUDIO_PWM_PERIOD / AUDIO_SAMPLING_RATE;
+
+  PWMGenIntTrigEnable(PWM0_BASE, PWM_GEN_2, PWM_INT_CNT_ZERO);
+
+  PWMOutputState(PWM0_BASE, PWM_OUT_5_BIT, true);
+  PWMGenEnable(PWM0_BASE, PWM_GEN_2);
+}
+
+uint32_t gPWMSample = 0; // PWM sample counter
+void PWM_ISR(void)
+{
+    PWMGenIntClear(PWM0_BASE, PWM_GEN_2, PWM_INT_CNT_ZERO); // clear PWM interrupt flag
+    // waveform sample index
+    int i = (gPWMSample++) / gSamplingRateDivider;
+    // write directly to the PWM compare B register
+    PWM0_2_CMPB_R = 1 + gWaveform[i];
+    if (i > gWaveformSize) { // if at the end of the waveform array
+        // disable these interrupts
+        PWMIntDisable(PWM0_BASE, PWM_INT_GEN_2);
+        // reset sample index so the waveform starts from the beginning
+        gPWMSample = 0;
+    }
+}
+

audio.h

@@ -0,0 +1,6 @@
+#ifndef AUDIO_C
+#define AUDIO_C
+
+void configure_audio();
+
+#endif

audio_waveform.h

@@ -0,0 +1,17 @@
+/*
+ * audio_waveform.h
+ *
+ *  Created on: Apr 15, 2020
+ *      Author: Gene Bogdanov
+ *
+ *  ECE 3849 Lab 3 Audio Waveform header
+ */
+
+#ifndef AUDIO_WAVEFORM_H_
+#define AUDIO_WAVEFORM_H_
+
+#define AUDIO_SAMPLING_RATE 16000   // [samples/sec] waveform sampling rate
+extern const uint8_t gWaveform[];   // waveform array, stored in the flash
+extern const size_t gWaveformSize;  // number of elements in the waveform array
+
+#endif /* AUDIO_WAVEFORM_H_ */

frequency.h

@@ -4,6 +4,7 @@
 
 #define PWM_FREQUENCY 20000 // PWM frequency = 20 kHz
 
+void start_signal(void);
 void start_frequency_scan(void);
 void set_pwm_period(uint32_t period);
 

main.c

@@ -32,6 +32,7 @@
 #include "sampling.h"
 #include "buttons.h"
 #include "frequency.h"
+#include "audio.h"
 #include "kiss_fft.h"
 #include "_kiss_fft_guts.h"
 
@@ -126,6 +127,7 @@ int main(void)
     ButtonInit();
     start_cputimer();
     start_frequency_scan();
+    configure_audio();
 
     Crystalfontz128x128_Init(); // Initialize the LCD display driver
     Crystalfontz128x128_SetOrientation(LCD_ORIENTATION_UP); // set screen orientation
@@ -255,6 +257,9 @@ void handle_user_input() {
             case SW2:
                 set_pwm_period(--gPWMPeriod);
                 break;
+            case Right:
+                PWMIntEnable(PWM0_BASE, PWM_INT_GEN_2);
+                break;
         }
 
         Semaphore_pend(options_sem, BIOS_WAIT_FOREVER);

rtos.cfg

@@ -599,5 +599,10 @@ gateHwi0Params.instance.name = "gateHwiDMA";
 Program.global.gateHwi0 = GateHwi.create(gateHwi0Params);
 var m3Hwi1Params = new m3Hwi.Params();
 m3Hwi1Params.instance.name = "m3Hwi1";
-m3Hwi1Params.priority = 4;
+m3Hwi1Params.priority = 0;
 Program.global.m3Hwi1 = m3Hwi.create(35, "&capture_handler", m3Hwi1Params);
+var m3Hwi2Params = new m3Hwi.Params();
+m3Hwi2Params.instance.name = "m3Hwi2";
+m3Hwi2Params.priority = 0;
+m3Hwi2Params.enableInt = true;
+Program.global.m3Hwi2 = m3Hwi.create(28, "&PWM_ISR", m3Hwi2Params);