control.c: adjust the lowest mode timing

projects/step-up/control.c

@@ -20,7 +20,7 @@ static pattern_t blink_pattern[] = {
 
 static pattern_t slow_pattern[] = {
 	{ 1, 0x1 },
-	{ 0, 0x10 },
+	{ 0, 0x18 },
 	PATTERN_END
 };