diff --git a/PSE-firmware b/PSE-firmware
index d087767..bf08fc6 160000
--- a/PSE-firmware
+++ b/PSE-firmware
@@ -1 +1 @@
-Subproject commit d0877672a3653eeed5fe7b65185ec45d93943f26
+Subproject commit bf08fc69ff21c28482ade1eca086867e619b7fea
diff --git a/main.c b/main.c
index aa9d9de..e61d4bf 100644
--- a/main.c
+++ b/main.c
@@ -79,7 +79,7 @@ int main(int argc, char** argv){
     exit(-1);
   }
 
-  window = SDL_CreateWindow( "SDL Tutorial", SDL_WINDOWPOS_UNDEFINED, SDL_WINDOWPOS_UNDEFINED, LCD_WIDTH, LCD_HEIGHT, SDL_WINDOW_SHOWN );
+  window = SDL_CreateWindow("PSE emulator", SDL_WINDOWPOS_UNDEFINED, SDL_WINDOWPOS_UNDEFINED, LCD_WIDTH, LCD_HEIGHT, SDL_WINDOW_SHOWN );
   if(window == NULL){
     printf("Window could not be created! SDL_Error: %s\n", SDL_GetError());
   }
diff --git a/stm32f1xx_hal.c b/stm32f1xx_hal.c
index 342fb11..683c76e 100644
--- a/stm32f1xx_hal.c
+++ b/stm32f1xx_hal.c
@@ -35,19 +35,23 @@ static void* tim_handler(void* arg){
   struct timespec start, current;
   clock_gettime(CLOCK_MONOTONIC, &start);
   
-  while(htim->started){
-    uint64_t delay_ps = (uint64_t) 15625 * (htim->presc+1) * (htim->period+1);
-    printf("delay : %lu\n", delay_ps);
+  uint64_t delay_ps = (uint64_t) 15625 * (htim->presc+1) * (htim->period+1);
 
+  int exec_counter = 0;
+  
+  while(htim->started){
     clock_gettime(CLOCK_MONOTONIC, &current);
     uint64_t time = (uint64_t) 1000000000 * (current.tv_sec - start.tv_sec) + (current.tv_nsec - start.tv_nsec);
-    if(delay_ps / 1000 > time)
-      usleep((delay_ps / 1000 - time) / 1000);
-    else printf("oups");
-    
-    clock_gettime(CLOCK_MONOTONIC, &start);
-    
-    HAL_TIM_PeriodElapsedCallback(htim);
+
+    unsigned int nb_exec = time * 1000 / delay_ps;
+    int backlog = nb_exec - exec_counter;
+    while(backlog > 0){  
+      if(backlog > 10)
+        printf("timer simulation lagging behind (%d ticks)\n", backlog);
+      HAL_TIM_PeriodElapsedCallback(htim);
+      exec_counter++;
+      backlog = nb_exec - exec_counter;
+    }
   }
   return NULL;
 }