Make detection happen quicker

Author: rhgndf

ch32v305/src/hw/i2s_hw.c

@@ -1,6 +1,7 @@
 #include "i2s_hw.h"
 
 #include <assert.h>
+#include <math.h>
 #include <stddef.h>
 
 #include "debug.h"
@@ -319,11 +320,13 @@ bool i2s_needs_reset(void)
     // If i2s is not bitslipped, we expect coincidences to be random with 50% probability
     // We do a two sided Z-test here
     bool ret = false;
-    if ((s_i2s_reset_coincidences < s_i2s_coincidences_samples / 2 - 1000) ||
-        (s_i2s_reset_coincidences > s_i2s_coincidences_samples / 2 + 1000)) {
+    double n = (double)s_i2s_coincidences_samples;
+    uint32_t thres = 1.2879 * sqrt(n);
+    if ((s_i2s_reset_coincidences < s_i2s_coincidences_samples / 2 - thres) ||
+        (s_i2s_reset_coincidences > s_i2s_coincidences_samples / 2 + thres)) {
         // Is bitslipped, request reset outside the ISR.
         uint32_t sample_32 = ((uint32_t)s_rx_dma_buf[0] << 16) | s_rx_dma_buf[1];
-        printf("coincidences: %ld/%ld, sample: %08lX\n", s_i2s_reset_coincidences, s_i2s_coincidences_samples, sample_32);
+        printf("coincidences: %ld/%ld, thres: %ld, sample: %08lX\n", s_i2s_reset_coincidences, s_i2s_coincidences_samples, thres, sample_32);
         ret = true;
     }
     s_i2s_coincidences_samples = 0;

ch32v305/src/main.c

@@ -218,9 +218,16 @@ static void TLV320_I2S_CheckBitslip(void)
 {
     static uint64_t last_check_tick = 0U;
     static uint8_t initialized = 0U;
+    static uint8_t enabled = 1U;
+    static uint8_t false_checks_in_a_row = 0U;
     uint64_t now_tick = SysTick->CNT;
     uint64_t check_period_ticks = ticks_from_ms(100U);
 
+    if(enabled == 0U)
+    {
+        return;
+    }
+
     if(initialized == 0U)
     {
         last_check_tick = now_tick;
@@ -237,13 +244,22 @@ static void TLV320_I2S_CheckBitslip(void)
 
     if(i2s_needs_reset())
     {
+        false_checks_in_a_row = 0U;
         printf("bitslipped, resetting\n");
         i2s_hw_deinit();
         Delay_Ms(1);
         i2s_hw_init();
         i2s_hw_enable(ENABLE);
         s_tlv320_i2s_report_initialized = 0U;
+        enabled = 1U;
         initialized = 0U;
+        return;
+    }
+
+    ++false_checks_in_a_row;
+    if(false_checks_in_a_row >= 20U)
+    {
+        enabled = 0U;
     }
 }