diff --git a/MyCode/App_Auto.c b/MyCode/App_Auto.c
index 245f85c..445aac2 100644
--- a/MyCode/App_Auto.c
+++ b/MyCode/App_Auto.c
@@ -59,10 +59,11 @@ static uint8_t s_seq_po;
 #define ARP_CH 12 /* 逐音琶音；垫音通道同一拍会叠多个音，不参与网格 */
 static uint8_t s_seq_step[16];
 static struct { uint8_t ch, in, out, used; } s_seq_slot[SEQ_SLOTS];
-/* 红圈：同一拍叠上来的音向右 1 个音（图上 1 tik = 两个格子 = 一个八分音符）。 */
+/* 第 5 拍会叠来一个多余触发。丢掉它，不占发音顺序，第 6 个音就落在下一拍。 */
 static uint32_t s_grid_t0;
 static uint16_t s_grid_unit;
 static uint8_t s_grid_on;
+static uint8_t s_seq_drop;
 static uint16_t s_pending_hold_ms;
 static uint8_t s_slot_hold4[SEQ_SLOTS];
 static volatile uint16_t s_hold_report;
@@ -181,6 +182,7 @@ static int App_Auto_MapSeq(int channel, int key, int is_on, int *out)
     int i;
 
     s_pending_hold_ms = 0;
+    s_seq_drop = 0;
     App_Auto_SeqRefresh();
     if (!s_seq_on || channel == BASS_CH || channel == DRUM_CH)
         return 0;
@@ -192,8 +194,13 @@ static int App_Auto_MapSeq(int channel, int key, int is_on, int *out)
             if (s_seq_slot[i].used && s_seq_slot[i].ch == (uint8_t)ch
                 && s_seq_slot[i].in == (uint8_t)key)
             {
-                *out = s_seq_slot[i].out;
-                s_pending_hold_ms = (uint16_t)s_slot_hold4[i] * 4u;
+                if (s_seq_slot[i].used == 2u)
+                    s_seq_drop = 1u;
+                else
+                {
+                    *out = s_seq_slot[i].out;
+                    s_pending_hold_ms = (uint16_t)s_slot_hold4[i] * 4u;
+                }
                 s_seq_slot[i].used = 0;
                 s_slot_hold4[i] = 0;
                 return 1;
@@ -203,21 +210,44 @@ static int App_Auto_MapSeq(int channel, int key, int is_on, int *out)
         return 1;
     }
     {
-        uint8_t step = (uint8_t)(s_seq_step[ch] & 7u);
+        uint8_t step;
         uint32_t now;
-        *out = s_seq[step];
-        s_seq_step[ch] = (uint8_t)((step + 1u) & 7u);
-        /* 琶音通道同一拍里的后一个音，晚一个八分音符再发出 */
+        uint8_t piled = 0;
         if (ch == ARP_CH)
         {
             now = wk_timebase_get();
-            if (s_grid_on && (now - s_grid_t0) < (uint32_t)(s_grid_unit / 4u))
-                s_pending_hold_ms = s_grid_unit;
-            else
+            if (!s_grid_on || s_grid_unit == 0u
+                || (now - s_grid_t0) >= (uint32_t)(s_grid_unit / 4u))
                 s_grid_unit = App_Auto_EighthMs();
+            piled = (s_grid_on
+                     && (now - s_grid_t0) < (uint32_t)(s_grid_unit / 4u)) ? 1u : 0u;
             s_grid_t0 = now;
             s_grid_on = 1u;
         }
+        if (piled)
+        {
+            /* 同一拍的后一个触发不发声，也不占用下一个顺序音 */
+            s_seq_drop = 1u;
+            for (i = 0; i < SEQ_SLOTS; i++)
+            {
+                if (!s_seq_slot[i].used)
+                {
+                    s_seq_slot[i].used = 2u;
+                    s_seq_slot[i].ch = (uint8_t)ch;
+                    s_seq_slot[i].in = (uint8_t)key;
+                    s_seq_slot[i].out = 0;
+                    return 1;
+                }
+            }
+            s_seq_slot[0].used = 2u;
+            s_seq_slot[0].ch = (uint8_t)ch;
+            s_seq_slot[0].in = (uint8_t)key;
+            s_seq_slot[0].out = 0;
+            return 1;
+        }
+        step = (uint8_t)(s_seq_step[ch] & 7u);
+        *out = s_seq[step];
+        s_seq_step[ch] = (uint8_t)((step + 1u) & 7u);
     }
     for (i = 0; i < SEQ_SLOTS; i++)
     {
@@ -556,6 +586,8 @@ static int App_Auto_MapNoteOn(int channel, int key)
     }
 
     out = App_Auto_MapNote(channel, key, &flags, 1);
+    if (s_seq_drop)
+        return out;
     if (channel >= 0 && channel < 16)
     {
         uint16_t bit = (uint16_t)(1u << channel);
@@ -610,6 +642,8 @@ static void Func_CallBack_NoteOff(int channel,int key)
     MidiFifoItem_t midimsg = {0};
     uint8_t flags = 0;
     int out_key = App_Auto_MapNote(channel, key, &flags, 0);
+    if (s_seq_drop)
+        return;
     midimsg.msg[0] = 0x80 | (channel & 0x0F);
     midimsg.msg[1] = (uint8_t)out_key;
     midimsg.msg[2] = 0;
@@ -630,6 +664,8 @@ static void Func_CallBack_NoteOn(int channel,int key,int vel)
     }
     else
         out_key = App_Auto_MapNoteOn(channel, key);
+    if (s_seq_drop)
+        return;
 
     midimsg.msg[0] = 0x90 | (channel & 0x0F);
     midimsg.msg[1] = (uint8_t)out_key;