audio engine..

src/cppmain.cc

@@ -9,7 +9,7 @@
 #include <sstream>
 #include <iomanip>
 
-#define SAMPLE_FREQ 44200
+    #define SAMPLE_FREQ 42000
 #define SAMPLE_MAX 4096
 #define BUFFER_SIZE 256
 #define BLOCK_SIZE 128
@@ -25,8 +25,6 @@ static volatile bool process_block2{ true };
 // time
 static u64 inf_phasor{ 0 };
 
-// misc
-static volatile int freq = 100;
 
 namespace Heck {
     bool debug_suspend_active = false;
@@ -69,7 +67,6 @@ namespace Heck {
     void irq1_cb()
     {
         debug_suspend_continue();
-        freq += 10;
     }
 
     void timer3_cb()
@@ -159,16 +156,27 @@ namespace Heck {
     }
 
 
+    u32 saw(u64 t, float freq_hz)
+    {
+        u32 ret{ 0 };
+        u32 samps = hz_to_samps(freq_hz);
+        u32 normalizing_factor = SAMPLE_MAX / samps;
+
+        ret = t % samps;
+        ret *= normalizing_factor;
+
+        return ret;
+    }
+
     void calculate_audio()
     {
         //        log("calculate_audio time: ");
         u32 *b = block;
         u64 t = inf_phasor;
-        u32 samps = hz_to_samps(freq);
-        u32 val{ 0 };
+
         for (int i = 0; i < BLOCK_SIZE; i++) {
-            val = t % samps;
-            b[i] = val * 8;
+            b[i] = saw(t, 80);
+//            b[i] *= saw(t, 20);
             t++;
         }
     }

src/cppmain.h

@@ -30,6 +30,8 @@ extern "C" {
     #include <cstdint>
     #include <string>
 
+using u8 = uint8_t;
+using u16 = uint16_t;
 using u32 = uint32_t;
 using u64 = uint64_t;
 

src/init.c

@@ -171,7 +171,7 @@ void dac_init(void)
     htim_dac1.Instance = TIM2;
     htim_dac1.Init.Prescaler = 0;
     htim_dac1.Init.CounterMode = TIM_COUNTERMODE_UP;
-    htim_dac1.Init.Period = 2000;// * 10000;
+    htim_dac1.Init.Period = 2000;// *100;
     htim_dac1.Init.AutoReloadPreload = TIM_AUTORELOAD_PRELOAD_ENABLE;
     if (HAL_TIM_Base_Init(&htim_dac1) != HAL_OK) {
         Error_Handler();
@@ -325,6 +325,6 @@ void heck_init()
     //    heck_debug_suspend();
     blinky_led_init();
     dac_init();
-    adc_init();
+//    adc_init();
     rng_init();
 }