From 35822a08c95f5fb3022c316d27ba0c0cef91745a Mon Sep 17 00:00:00 2001
From: Petr Baudis <pasky@ucw.cz>
Date: Fri, 16 Nov 2012 18:37:24 +0100
Subject: [PATCH] Add synchronization byte \xAC at the beginning of RGB burst

---
 arduino/controlled/controlled.ino | 5 +++++
 host/ledbar.c                     | 6 +++++-
 host_python/send_to_serial.py     | 2 +-
 3 files changed, 11 insertions(+), 2 deletions(-)

diff --git a/arduino/controlled/controlled.ino b/arduino/controlled/controlled.ino
index a5eef65..2d8e56b 100644
--- a/arduino/controlled/controlled.ino
+++ b/arduino/controlled/controlled.ino
@@ -23,6 +23,11 @@ void setup()
 void loop()
 {
   int led, i;
+  /* Wait for synchronization. */
+  do {
+    while (!Serial.available());
+  } while (Serial.read() != 0xAC);
+  /* Set LEDs. */
   for (led = 0; led < cpinsets; led++) {
     for (i = 0; i < CH; i++) {
       while (!Serial.available());
diff --git a/host/ledbar.c b/host/ledbar.c
index 7168054..18fe5da 100644
--- a/host/ledbar.c
+++ b/host/ledbar.c
@@ -298,6 +298,9 @@ void drawScreen(SDL_Surface* screen, int t, FILE* fp)
 
     if(SDL_MUSTLOCK(screen) && SDL_LockSurface(screen) < 0) return;
 
+    if (fp)
+	fwrite("\xAC", 1, 1, fp);
+
     for (i=0; i<BOXES; ++i) {
         program(i, t, &r, &g, &b);
         if (fp) {
@@ -316,7 +319,8 @@ void drawScreen(SDL_Surface* screen, int t, FILE* fp)
 
     if (SDL_MUSTLOCK(screen)) SDL_UnlockSurface(screen);
     SDL_Flip(screen);
-    fflush(fp);
+    if (fp)
+	fflush(fp);
 }
 
 
diff --git a/host_python/send_to_serial.py b/host_python/send_to_serial.py
index 6941b29..10e30b6 100755
--- a/host_python/send_to_serial.py
+++ b/host_python/send_to_serial.py
@@ -54,7 +54,7 @@ def main():
 
     try:
         while True:
-            data = ''
+            data = '\xAC'
             to_read = number*3
             while to_read > 0:
                 read = sys.stdin.read(to_read)