fix reporting to match time elapsed

1 files changed, 10 insertions, 9 deletions

diff --git a/Core/Src/main.c b/Core/Src/main.c
index 6b7fad0..56a0723 100644
--- a/Core/Src/main.c
+++ b/Core/Src/main.c
@@ -34,11 +34,12 @@ typedef struct  {
 

 /* Private define ------------------------------------------------------------*/

 /* USER CODE BEGIN PD */

-#define SAMPLE_COUNT    (512)   // Sample count per half-transfer

-#define MIC_OFFSET_DB   (  0.f) // Linear offset

-#define MIC_SENSITIVITY (-26.f) // dBFS value expected at MIC_REF_DB

-#define MIC_REF_DB      ( 94.f) // dB where sensitivity is specified

-#define MIC_BITS        (18)

+#define SAMPLE_COUNT        (256)   // Sample count per half-transfer

+#define SAMPLES_PER_REPORT  (48000) // Report every second given our 48 kHz rate

+#define MIC_OFFSET_DB       (  0.f) // Linear offset

+#define MIC_SENSITIVITY     (-26.f) // dBFS value expected at MIC_REF_DB

+#define MIC_REF_DB          ( 94.f) // dB where sensitivity is specified

+#define MIC_BITS            (18)

 /* USER CODE END PD */

 

 /* Private macro -------------------------------------------------------------*/

@@ -58,7 +59,7 @@ UART_HandleTypeDef huart2;
 static const uint8_t I2S_Frame_Buffer[8] = {

   0x00, 0x00, 0x00, 0x00, 0xFF, 0xFF, 0xFF, 0xFF

 };

-static uint8_t I2S_Receive_Buffer[SAMPLE_COUNT * sizeof(sample_t)];

+static uint8_t I2S_Receive_Buffer[SAMPLE_COUNT * 2 * sizeof(sample_t)];

 

 float ln10;

 float MIC_REF_AMPL;

@@ -547,16 +548,16 @@ void SPI_DMAHalfTransmitReceiveCplt(DMA_HandleTypeDef *hdma)
     float f = process(qfp_int2float(sample[i].value / 4));

     DB_Sum_Squares = qfp_fadd(DB_Sum_Squares, qfp_fmul(f, f));

   }

-  DB_Count += SAMPLE_COUNT / 8;

+  DB_Count += SAMPLE_COUNT * 2; // Pretend we sampled the entire I2S buffer

 

-  if (DB_Count > 48000 / 4) {

+  if (DB_Count > SAMPLES_PER_REPORT) {

     float rms = qfp_fsqrt(qfp_fdiv(DB_Sum_Squares, qfp_uint2float(DB_Count)));

     float db = qfp_fadd(MIC_OFFSET_DB + MIC_REF_DB, qfp_fmul(20.f,

       qfp_flog10(qfp_fdiv(rms, MIC_REF_AMPL))));

     DB_Sum_Squares = 0.f;

     DB_Count = 0;

 

-    printf("%d\r\n", qfp_float2int(db));

+    printf("%d dB\r\n", qfp_float2int(db));

   }

 }

 /* USER CODE END 4 */