diff --git a/doc/lab03-silly_led/main.typ b/doc/lab03-silly_led/main.typ
index 2005f2d..259d36a 100644
--- a/doc/lab03-silly_led/main.typ
+++ b/doc/lab03-silly_led/main.typ
@@ -2,10 +2,12 @@
 
 = Linux System Programming
 
-// TODO
+== File system
+This laboratory is focused on the user space. We make an application to change the blinking frequency of a led with button.
 
-This laboratory is focused on the user space. We make an application to change
-the blinking frequency of a led with button.
+=== Buttons
+
+// TODO
 
 It has some difficulties to locate the button on the GPIOs. Because this is not
 the same as we have done in the module in the precedent laboratory.
@@ -18,3 +20,29 @@ discover the timer_fd
 all is file
 
 all can be in the epoll to manage all event from files
+
+
+=== timer
+- epoll
+- thread
+- 1 consumer, 1 provider, no need mutex
+
+- create timer empty
+- set timer with `timerfd_set_time`
+- definition of the initial time and not the repetition time, to use only one timer
+- link to epoll
+
+
+=== syslog
+- one opening
+```c openlog("CSEL Logs", LOG_PID, LOG_USER);```
+LOG_PID is used to keep the PID of the process in the log, and LOG_USER is used to specify the facility of the log (what type of programme).
+
+```c syslog(LOG_INFO, "Start logging silly led-controller"); // INFO level```
+
+
+=== Multithreading
+- one thread for the button, one for the led
+- button write time
+- led read time and sleep for this time
+- no mutex because we have only one provider
\ No newline at end of file