diff --git a/src/06-mini-project/daemon/gpio/button.c b/src/06-mini-project/daemon/gpio/button.c
index 983c98a..31ee7a6 100644
--- a/src/06-mini-project/daemon/gpio/button.c
+++ b/src/06-mini-project/daemon/gpio/button.c
@@ -15,14 +15,15 @@
 #define GPIO_UNEXPORT "/sys/class/gpio/unexport"
 #define GPIO_BTN_BASE "/sys/class/gpio/gpio"
 
-#define MAX_EVENTS 10
-atomic_int ev_tail = 0;
+#define MAX_BTN 10
+btn_t* btn_list[MAX_BTN];
 
 int epoll_fd;
-struct epoll_event ev[MAX_EVENTS];
+struct epoll_event ev[MAX_BTN];
+atomic_int btn_tail = 0;
 pthread_t epoll_thread_id;
 
-int btn_add_epoll_event(btn_t* btn);
+void btn_add_epoll_event(btn_t* btn, int tail);
 void epoll_init();
 static void* epoll_thread(void* arg);
 
@@ -31,29 +32,28 @@ btn_t* btn_init(btn_type_t type) {
     if (btn == NULL) return NULL;
 
     char gpio_path[32] = GPIO_BTN_BASE;
-    char pin[32];
     switch (type) {
         case BTN_INCREASE:
-            strcpy(pin, GPIO_BTN_INCREASE);
+            strcpy(btn->pin, GPIO_BTN_INCREASE);
             break;
         case BTN_DECREASE:
-            strcpy(pin, GPIO_BTN_DECREASE);
+            strcpy(btn->pin, GPIO_BTN_DECREASE);
             break;
         case BTN_MODE:
-            strcpy(pin, GPIO_BTN_MODE);
+            strcpy(btn->pin, GPIO_BTN_MODE);
             break;
         default:
             printf("Invalid button type\n");
             return NULL;
     }
-    strcat(gpio_path, pin);
+    strcat(gpio_path, btn->pin);
 
     int f = open(GPIO_UNEXPORT, O_WRONLY);
-    write(f, pin, strlen(pin));
+    write(f, btn->pin, strlen(btn->pin));
     close(f);
 
     f = open(GPIO_EXPORT, O_WRONLY);
-    write(f, pin, strlen(pin));
+    write(f, btn->pin, strlen(btn->pin));
     close(f);
 
     char direction_path[100];
@@ -78,16 +78,26 @@ btn_t* btn_init(btn_type_t type) {
 
     f = open(value_path, O_RDONLY);
     if (f == -1) {
-        printf("Failed to setup button on pin %s\n", pin);
+        printf("Failed to setup button on pin %s\n", btn->pin);
         return NULL;
     }
-    btn->gpio = f;
+    btn->fd = f;
 
     // Dummy read to clear initial state before waiting
     char buf[2];
-    pread(btn->gpio, buf, sizeof(buf), 0);
+    pread(btn->fd, buf, sizeof(buf), 0);
 
-    btn_add_epoll_event(btn);
+    int tail = atomic_fetch_add(&btn_tail, 1);
+    if (tail >= MAX_BTN) {
+        perror("Failed to add epoll event");
+        exit(EXIT_FAILURE);
+    }
+
+    btn_list[tail] = btn;
+    if (tail == 0) {
+        epoll_init();
+    }
+    btn_add_epoll_event(btn, tail);
 
     return btn;
 }
@@ -97,38 +107,21 @@ void btn_set_callback(btn_t* btn, btn_callback_t callback) {
 }
 
 // TODO add mutex to protect this function
-int btn_add_epoll_event(btn_t* btn) {
-    int tail = atomic_fetch_add(&ev_tail, 1);
-    if (tail >= MAX_EVENTS-1) {
-        perror("Failed to add epoll event");
-        return -1;
-    }
-
-    if (tail == 0) {
-        epoll_init();
-    }
+void btn_add_epoll_event(btn_t* btn, int tail) {
 
     // EPOLLIN is working well as EPOLLPRI (which is more used for priority data)
     // EPOLLERR is used to detect if there is an error
     // EPOLLET is for edge triggered mode (non-blocking)
     ev[tail].events = EPOLLIN | EPOLLERR | EPOLLET;
-    ev[tail].data.fd = btn->gpio;
-    int ret = epoll_ctl(epoll_fd, EPOLL_CTL_ADD, btn->gpio, &ev[tail]);
+    ev[tail].data.fd = btn->fd;
+
+    int ret = epoll_ctl(epoll_fd, EPOLL_CTL_ADD, btn->fd, &ev[tail]);
     if (ret < 0) {
         perror("Failed to add epoll event");
-        return -1;
     }
-    return tail;
 }
 
 void epoll_init(){
-    if (pthread_create(&epoll_thread_id, NULL, epoll_thread, NULL) != 0) {
-        perror("Failed to create timer thread");
-        exit(30);
-    }
-}
-
-static void* epoll_thread(void* arg) {
     int epfd = epoll_create1(0);
     if (epfd < 0) {
         perror("Failed to create epoll instance");
@@ -136,15 +129,44 @@ static void* epoll_thread(void* arg) {
     }
     epoll_fd = epfd;
 
+    if (pthread_create(&epoll_thread_id, NULL, epoll_thread, NULL) != 0) {
+        perror("Failed to create timer thread");
+        exit(30);
+    }
+}
+
+static void* epoll_thread(void* arg) {
     while (1) {
-        struct epoll_event events[MAX_EVENTS];
-        int n = epoll_wait(epoll_fd, events, MAX_EVENTS, -1);
+        struct epoll_event events[MAX_BTN];
+        int n = epoll_wait(epoll_fd, events, MAX_BTN, -1);
         if (n < 0) {
             perror("epoll_wait");
             continue;
         }
         for (int i = 0; i < n; i++) {
-
+            char buf[2];
+            int fd = events[i].data.fd;
+            int tail = -1;
+            btn_t* btn = NULL;
+            for (int j = 0; j < MAX_BTN; j++) {
+                if (btn_list[j] == NULL) continue;
+                if (btn_list[j]->fd == fd) {
+                    tail = j;
+                    btn = btn_list[j];
+                    break;
+                }
+            }
+            if (tail == -1) {
+                printf("No button found for fd %d\n", fd);
+                continue;
+            }
+            pread(btn->fd, buf, sizeof(buf), 0);
+            if (buf[0] == '1') {
+                printf("Button %s pressed\n", btn->pin);
+                if (btn->callback != NULL) {
+                    btn->callback();
+                }
+            }
         }
     }
 }
diff --git a/src/06-mini-project/daemon/gpio/button.h b/src/06-mini-project/daemon/gpio/button.h
index a87dda7..ed939a8 100644
--- a/src/06-mini-project/daemon/gpio/button.h
+++ b/src/06-mini-project/daemon/gpio/button.h
@@ -14,7 +14,8 @@ typedef enum {
 typedef void (*btn_callback_t)();
 
 typedef struct {
-    int gpio;
+    int fd;
+    char pin[32];
     btn_callback_t callback;
 } btn_t;
 
diff --git a/src/06-mini-project/daemon/main.c b/src/06-mini-project/daemon/main.c
index 5b299c3..b460aa0 100644
--- a/src/06-mini-project/daemon/main.c
+++ b/src/06-mini-project/daemon/main.c
@@ -35,83 +35,21 @@ typedef struct {
     int epoll_fd;
 } ThreadData;
 
-// constant
-const char* GPIO_BTN[NBR_BTN] = {GPIO_BTN1, GPIO_BTN2, GPIO_BTN3};
-const char* BTN[NBR_BTN] =  {BTN1, BTN2, BTN3};
+ThreadData data;
 
+void period_inc() {
+    data.flash_period_ms += 100;
+    printf("period_inc: flash_period_ms=%ld\n", data.flash_period_ms);
+}
 
-void* btn_thread(void* arg) {
-    ThreadData* data = (ThreadData*)arg;
+void period_dec() {
+    data.flash_period_ms -= 100;
+    printf("period_dec: flash_period_ms=%ld\n", data.flash_period_ms);
+}
 
-    btn_init(BTN_INCREASE);
-    btn_init(BTN_DECREASE);
-    btn_init(BTN_MODE);
-
-
-    // Dummy read to clear initial state before waiting
-    char buf[2];
-    for(int i=0; i<NBR_BTN; i++) {
-        pread(btn[i], buf, sizeof(buf), 0);
-    }
-
-    printf("Waiting for button presses...\n");
-
-    // Event main loop
-    while (1) {
-        struct epoll_event events[NBR_BTN];
-
-        // Timeout is -1: Block infinitely until an event occurs!
-        int n = epoll_wait(epfd, events, 1, -1);
-
-        if (n < 0) {
-            perror("epoll_wait error");
-            break;
-        }
-
-        for (int i = 0; i < n; i++) {
-            // read btn file
-            pread(events[i].data.fd, buf, sizeof(buf), 0);
-
-            if (events[i].data.fd == btn[0]) {
-                if (buf[0] == '1') {
-                    data->flash_period_ms += 200;
-                    char* log_msg = malloc(100);
-                    snprintf(log_msg, 100, "Increase flash period to %ld ms", data->flash_period_ms);
-                    syslog(LOG_INFO, "%s", log_msg);
-                    printf("%s\n", log_msg);
-                    free(log_msg);
-                }
-
-            } else if (events[i].data.fd == btn[1]) {
-                if (buf[0] == '1') {
-                    data->flash_period_ms = DEFAULT_TIME_MS;
-                    char* log_msg = malloc(100);
-                    snprintf(log_msg, 100, "Reset flash period to %ld ms", data->flash_period_ms);
-                    syslog(LOG_INFO, "%s", log_msg);
-                    printf("%s\n", log_msg);
-                    free(log_msg);
-                }
-
-            } else if (events[i].data.fd == btn[2]) {
-                if (buf[0] == '1') {
-                    data->flash_period_ms -= 200;
-                    if (data->flash_period_ms <= 0) {
-                        data->flash_period_ms = 200; // Minimum period of 200ms
-                    }
-                    char* log_msg = malloc(100);
-                    snprintf(log_msg, 100, "Decrease flash period to %ld ms", data->flash_period_ms);
-                    syslog(LOG_INFO, "%s", log_msg);
-                    printf("%s\n", log_msg);
-                    free(log_msg);
-                }
-            }
-        }
-    }
-
-    for (int i=0; i<NBR_BTN; i++) {
-        close(btn[i]);
-    }
-    close(epfd);
+void period_reset() {
+    data.flash_period_ms = DEFAULT_TIME_MS;
+    printf("period_reset: flash_period_ms=%ld\n", data.flash_period_ms);
 }
 
 static void* timer_thread(void* arg) {
@@ -162,7 +100,6 @@ static void* timer_thread(void* arg) {
 }
 
 int main(int argc, char* argv[]) {
-    ThreadData data;
     pthread_t thread;
     openlog("CSEL Logs", LOG_PID, LOG_USER);
     syslog(LOG_INFO, "Start logging silly led-controller");
@@ -182,17 +119,20 @@ int main(int argc, char* argv[]) {
 
     timer_link_to_epoll(&data.timer_fd, &data.epoll_fd);
 
+    btn_t* btn_inc = btn_init(BTN_INCREASE);
+    btn_t* btn_dec = btn_init(BTN_DECREASE);
+    btn_t* btn_mode = btn_init(BTN_MODE);
+
+    btn_set_callback(btn_inc, period_inc);
+    btn_set_callback(btn_dec, period_dec);
+    btn_set_callback(btn_mode, period_reset);
+
 
     if (pthread_create(&thread, NULL, timer_thread, &data) != 0) {
         perror("Failed to create timer thread");
         exit(30);
     }
 
-
-    // Setup button thread
-    pthread_t btn_thread_inst;
-    pthread_create(&btn_thread_inst, NULL, btn_thread, &data);
-
     while (1) {
         sleep(1);
     }