avg 횟수마다 반복 측정 간 500us 딜레이 추가

- avg 횟수에 따라 신호 위아래 폭이 작아지는 현상 개선을 위함
- 단일 채널 측정(mec)에는 원래 avg 사이 500us 존재, 전체 측정(maa)에는 없었음

project/ble_peripheral/ble_app_bladder_patch/measurement/adc121s051/dr_adc121s051.c

@@ -698,12 +698,11 @@ dr_adc_err_t dr_adc_burst_capture_transmit(uint8_t freq_option, uint16_t delay_u
 
         for (uint16_t avg_iter = 0; avg_iter < averaging; avg_iter++)
         {
-            /* Wait for previous echo to decay before next measurement
-             * 1ms = ~77cm round-trip decay time (sound speed 1.54mm/us)
-             * Skip delay on first iteration */
+            /* Wait for previous echo and ringing to decay before next measurement.
+             * Skip delay on first iteration. */
             if (avg_iter > 0)
             {
-                nrf_delay_us(500);  /* 500us between measurements */
+                nrf_delay_us(DR_ADC_AVG_INTER_BURST_GAP_US);
             }
 
             /* Re-select piezo channel before each burst
@@ -888,6 +887,12 @@ dr_adc_err_t dr_adc_capture_channel_only(uint8_t freq_option, uint16_t delay_us,
     /* repeat measurement 'averaging' times per channel */
     for (uint16_t avg_iter = 0; avg_iter < averaging; avg_iter++)
     {
+        /* Let the previous burst decay before the next averaged shot. */
+        if (avg_iter > 0)
+        {
+            nrf_delay_us(DR_ADC_AVG_INTER_BURST_GAP_US);
+        }
+
         /* TX burst pulse */
         switch (freq_option)
         {