diff --git a/main.c b/main.c
index 5327b2f..0cffb98 100644
--- a/main.c
+++ b/main.c
@@ -1220,6 +1220,7 @@ static void cmd_touchcal(BaseSequentialStream *chp, int argc, char *argv[])
   //extern int16_t touch_cal[4];
   int i;
 
+  chMtxLock(&mutex);
   chprintf(chp, "first touch upper left, then lower right...");
   touch_cal_exec();
   chprintf(chp, "done\r\n");
@@ -1229,7 +1230,7 @@ static void cmd_touchcal(BaseSequentialStream *chp, int argc, char *argv[])
     chprintf(chp, "%d ", config.touch_cal[i]);
   }
   chprintf(chp, "\r\n");
-  touch_start_watchdog();
+  chMtxUnlock(&mutex);
 }
 
 static void cmd_touchtest(BaseSequentialStream *chp, int argc, char *argv[])
diff --git a/ui.c b/ui.c
index 6ee4a94..242f3df 100644
--- a/ui.c
+++ b/ui.c
@@ -293,7 +293,7 @@ touch_cal_exec(void)
 
   do {
     status = touch_check();
-  } while(status != EVT_TOUCH_PRESSED);
+  } while(status != EVT_TOUCH_RELEASED);
   x1 = last_touch_x;
   y1 = last_touch_y;
 
@@ -303,7 +303,7 @@ touch_cal_exec(void)
 
   do {
     status = touch_check();
-  } while(status != EVT_TOUCH_PRESSED);
+  } while(status != EVT_TOUCH_RELEASED);
   x2 = last_touch_x;
   y2 = last_touch_y;
 
@@ -312,8 +312,8 @@ touch_cal_exec(void)
   config.touch_cal[2] = (x2 - x1) * 16 / 320;
   config.touch_cal[3] = (y2 - y1) * 16 / 240;
 
+  //redraw_all();
   touch_start_watchdog();
-  redraw_all();
 }
 
 void