From 619f0196154fd85878e7ba9969fa46d701d2c43f Mon Sep 17 00:00:00 2001
From: zouhaitao <zhongxuanzhen@xtell.cn>
Date: Wed, 8 Jul 2026 16:20:26 +0800
Subject: [PATCH] feat: add timeout protection to all SPI waits and extend
 initial NOP delay to 30 to prevent write collisions and deadlocks

---
 App/main.c | 27 +++++++++++++++------------
 1 file changed, 15 insertions(+), 12 deletions(-)

diff --git a/App/main.c b/App/main.c
index ea03be7..2f3c76a 100644
--- a/App/main.c
+++ b/App/main.c
@@ -146,6 +146,7 @@ void WS2812_Write24Bit(u8 g, u8 r, u8 b)
 {
     u8 data buf[10];
     u8 b0, b1, b2, b3, b4, b5, b6, b7, b8, b9;
+    u16 timeout;
     
     buf[0] = 0x00; // Prepend dummy 0x00 to absorb SPI hardware startup delay/glitch
     WS2812_EncodeByte(g, &buf[1]);
@@ -166,24 +167,26 @@ void WS2812_Write24Bit(u8 g, u8 r, u8 b)
     SPCTL = 0xD0;  // Enable SPI at SYSCLK/4 (3.0 MHz actual clock on board)
     
     SPDAT = b0; // Start transmitting dummy 0x00 (absorbs startup delay at MOSI=0)
-    // Wait at least 16 CPU cycles to ensure b0 has moved to the shifter
+    // Wait 30 NOPs to ensure b0 has moved to the shifter
     _nop_(); _nop_(); _nop_(); _nop_(); _nop_(); _nop_(); _nop_(); _nop_();
     _nop_(); _nop_(); _nop_(); _nop_(); _nop_(); _nop_(); _nop_(); _nop_();
+    _nop_(); _nop_(); _nop_(); _nop_(); _nop_(); _nop_(); _nop_(); _nop_();
+    _nop_(); _nop_(); _nop_(); _nop_(); _nop_(); _nop_();
     
     SPDAT = b1; // Buffer b1 (zero gap!)
     
-    // Transmission loop unrolled with double-buffering (zero gap SCLK)
-    while (!(SPSTAT & 0x80)); SPSTAT = 0xC0; SPDAT = b2;
-    while (!(SPSTAT & 0x80)); SPSTAT = 0xC0; SPDAT = b3;
-    while (!(SPSTAT & 0x80)); SPSTAT = 0xC0; SPDAT = b4;
-    while (!(SPSTAT & 0x80)); SPSTAT = 0xC0; SPDAT = b5;
-    while (!(SPSTAT & 0x80)); SPSTAT = 0xC0; SPDAT = b6;
-    while (!(SPSTAT & 0x80)); SPSTAT = 0xC0; SPDAT = b7;
-    while (!(SPSTAT & 0x80)); SPSTAT = 0xC0; SPDAT = b8;
-    while (!(SPSTAT & 0x80)); SPSTAT = 0xC0; SPDAT = b9;
+    // Transmission loop unrolled with double-buffering and timeout protection
+    timeout = 2000; while (!(SPSTAT & 0x80) && --timeout); SPSTAT = 0xC0; SPDAT = b2;
+    timeout = 2000; while (!(SPSTAT & 0x80) && --timeout); SPSTAT = 0xC0; SPDAT = b3;
+    timeout = 2000; while (!(SPSTAT & 0x80) && --timeout); SPSTAT = 0xC0; SPDAT = b4;
+    timeout = 2000; while (!(SPSTAT & 0x80) && --timeout); SPSTAT = 0xC0; SPDAT = b5;
+    timeout = 2000; while (!(SPSTAT & 0x80) && --timeout); SPSTAT = 0xC0; SPDAT = b6;
+    timeout = 2000; while (!(SPSTAT & 0x80) && --timeout); SPSTAT = 0xC0; SPDAT = b7;
+    timeout = 2000; while (!(SPSTAT & 0x80) && --timeout); SPSTAT = 0xC0; SPDAT = b8;
+    timeout = 2000; while (!(SPSTAT & 0x80) && --timeout); SPSTAT = 0xC0; SPDAT = b9;
     
-    while (!(SPSTAT & 0x80)); SPSTAT = 0xC0; // Wait for b8 to finish shifting, b9 moves to shifter
-    while (!(SPSTAT & 0x80)); SPSTAT = 0xC0; // Wait for b9 to finish shifting
+    timeout = 2000; while (!(SPSTAT & 0x80) && --timeout); SPSTAT = 0xC0; // Wait for b8 to finish shifting, b9 moves to shifter
+    timeout = 2000; while (!(SPSTAT & 0x80) && --timeout); SPSTAT = 0xC0; // Wait for b9 to finish shifting
     
     SPCTL = 0x90; // Disable SPI
     WS2812_DI = 0;