diff --git a/firmware/src/board_defs.h b/firmware/src/board_defs.h
index 39697aa..74bdb43 100644
--- a/firmware/src/board_defs.h
+++ b/firmware/src/board_defs.h
@@ -22,7 +22,7 @@
 #define ADC_KEY_CHN { 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, \
                      27, 26, 25, 24, 23, 22, 21, 20, 19, 18, 17, 16 }
 
-
+#define BUTTON_DEF { 13, 12, 11, 10 }
 #else
 
 #endif
diff --git a/firmware/src/button.c b/firmware/src/button.c
new file mode 100644
index 0000000..9cb7cca
--- /dev/null
+++ b/firmware/src/button.c
@@ -0,0 +1,84 @@
+/*
+ * Controller Buttons
+ * WHowe <github.com/whowechina>
+ * 
+ */
+
+#include "button.h"
+
+#include <stdint.h>
+#include <stdbool.h>
+
+#include "hardware/gpio.h" 
+#include "hardware/timer.h"
+#include "hardware/pwm.h"
+
+#include "config.h"
+#include "board_defs.h"
+
+static const uint8_t button_gpio[] = BUTTON_DEF;
+
+#define BUTTON_NUM (sizeof(button_gpio))
+
+static bool sw_val[BUTTON_NUM]; /* true if pressed */
+static uint64_t sw_freeze_time[BUTTON_NUM];
+
+static uint16_t button_reading;
+
+void button_init()
+{
+    for (int i = 0; i < BUTTON_NUM; i++) {
+        sw_val[i] = false;
+        sw_freeze_time[i] = 0;
+        int8_t gpio = button_gpio[i];
+        gpio_init(gpio);
+        gpio_set_function(gpio, GPIO_FUNC_SIO);
+        gpio_set_dir(gpio, GPIO_IN);
+        gpio_pull_up(gpio);
+    }
+
+    /* make valid initial reading */
+    button_reading = 0;
+    for (int i = 0; i < BUTTON_NUM; i++) {
+        sw_val[i] = !gpio_get(button_gpio[i]);
+        if (sw_val[i]) {
+            button_reading |= (1 << i);
+        }
+    }
+}
+
+uint8_t button_num()
+{
+    return BUTTON_NUM;
+}
+
+/* If a switch flips, it freezes for a while */
+#define DEBOUNCE_FREEZE_TIME_US 3000
+void button_update()
+{
+    uint64_t now = time_us_64();
+    uint16_t buttons = 0;
+
+    for (int i = BUTTON_NUM - 1; i >= 0; i--) {
+        bool sw_pressed = !gpio_get(button_gpio[i]);
+        
+        if (now >= sw_freeze_time[i]) {
+            if (sw_pressed != sw_val[i]) {
+                sw_val[i] = sw_pressed;
+                sw_freeze_time[i] = now + DEBOUNCE_FREEZE_TIME_US;
+            }
+        }
+
+        buttons <<= 1;
+        if (sw_val[i]) {
+            buttons |= 1;
+        }
+    }
+
+    button_reading = buttons;
+}
+
+uint16_t button_read()
+{
+    return button_reading;
+}
diff --git a/firmware/src/button.h b/firmware/src/button.h
new file mode 100644
index 0000000..55afde6
--- /dev/null
+++ b/firmware/src/button.h
@@ -0,0 +1,18 @@
+/*
+ * Controller Buttons
+ * WHowe <github.com/whowechina>
+ */
+
+#ifndef BUTTON_H
+#define BUTTON_H
+
+#include <stdint.h>
+#include <stdbool.h>
+#include "hardware/flash.h"
+
+void button_init();
+uint8_t button_num();
+void button_update();
+uint16_t button_read();
+
+#endif
diff --git a/firmware/src/main.c b/firmware/src/main.c
index 15c6892..c936837 100644
--- a/firmware/src/main.c
+++ b/firmware/src/main.c
@@ -13,6 +13,7 @@
 #include "pico/multicore.h"
 #include "pico/bootrom.h"
 
+#include "hardware/clocks.h"
 #include "hardware/gpio.h"
 #include "hardware/sync.h"
 #include "hardware/structs/ioqspi.h"
@@ -140,7 +141,6 @@ static void core0_loop()
         cli_run();
 
         savedata_loop();
-
         hammer_update();
         proc_midi();
 
@@ -148,13 +148,27 @@ static void core0_loop()
 
         cli_fps_count(0);
         sleep_until(next_frame);
-        next_frame += 1000;
+        next_frame += 300;
     }
 }
 
 /* if certain key pressed when booting, enter update mode */
 static void update_check()
 {
+    const uint8_t pins[] = BUTTON_DEF;
+    for (int i = 0; i < count_of(pins); i++) {
+        uint8_t gpio = pins[i];
+        gpio_init(gpio);
+        gpio_set_function(gpio, GPIO_FUNC_SIO);
+        gpio_set_dir(gpio, GPIO_IN);
+        gpio_pull_up(gpio);
+    }
+
+    if (!gpio_get(pins[0]) && !gpio_get(pins[1])) {
+        sleep_ms(100);
+        reset_usb_boot(0, 2);
+        return;
+    }
 }
 
 void init()
@@ -164,6 +178,8 @@ void init()
 
     update_check();
 
+    set_sys_clock_khz(166000, true);
+
     tusb_init();
     stdio_init_all();