diff --git a/CMakeLists.txt b/CMakeLists.txt
index aab2c38..45c9cc8 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -13,6 +13,10 @@ add_executable(${CMAKE_PROJECT_NAME}
 	src/main.c
 	src/sseg.c
 	src/sseg.h
+	src/buzzer.c
+	src/buzzer.h
+	src/buttons.c
+	src/buttons.h
 	src/pinout.h
 	src/sseg.pio
 	)
diff --git a/src/buttons.c b/src/buttons.c
new file mode 100644
index 0000000..9c69971
--- /dev/null
+++ b/src/buttons.c
@@ -0,0 +1,64 @@
+#include <string.h>
+
+#include "hardware/gpio.h"
+
+#include "pinout.h"
+
+#include "buttons.h"
+
+static const uint8_t m_pins[NUM_BUTTONS] = {
+	BTN_ON_PIN,
+	BTN_OFF_PIN
+};
+
+static uint8_t m_events[NUM_BUTTONS];
+static uint32_t m_last_change_time[NUM_BUTTONS];
+static uint32_t m_states;
+
+void buttons_init(void)
+{
+	for(int i = 0; i < NUM_BUTTONS; i++) {
+		gpio_init(m_pins[i]);
+		gpio_set_dir(m_pins[i], false); // true = output
+		gpio_set_pulls(m_pins[i], true, false); // enable pullup
+	}
+
+	memset(m_events, 0, sizeof(m_events));
+	memset(m_last_change_time, 0, sizeof(m_last_change_time));
+
+	m_states = 0;
+}
+
+void buttons_update_state(uint32_t time_ms)
+{
+	for(int i = 0; i < NUM_BUTTONS; i++) {
+		bool is_pressed  = gpio_get(m_pins[i]);
+		bool was_pressed = (m_states >> i) != 0;
+
+		m_events[i] = 0;
+		if(is_pressed && !was_pressed) {
+			m_events[i] |= BTN_EVENT_PRESSED;
+			m_states |= (1 << i);
+			m_last_change_time[i] = time_ms;
+		} else if(!is_pressed && was_pressed) {
+			m_events[i] |= BTN_EVENT_RELEASED;
+			m_states &= ~(1 << i);
+			m_last_change_time[i] = time_ms;
+		}
+	}
+}
+
+uint8_t buttons_get_events(button_id_t button)
+{
+	return m_events[button];
+}
+
+bool buttons_is_pressed(button_id_t button)
+{
+	return (m_states & (1 << button)) != 0;
+}
+
+uint32_t buttons_get_last_change_time(button_id_t button)
+{
+	return m_last_change_time[button];
+}
diff --git a/src/buttons.h b/src/buttons.h
new file mode 100644
index 0000000..d814dc7
--- /dev/null
+++ b/src/buttons.h
@@ -0,0 +1,24 @@
+#ifndef BUTTONS_H
+#define BUTTONS_H
+
+#include <stdint.h>
+#include <stdbool.h>
+
+#define BTN_EVENT_PRESSED (1 << 0)
+#define BTN_EVENT_RELEASED (1 << 1)
+
+typedef enum {
+	BTN_ON,
+	BTN_OFF,
+
+	NUM_BUTTONS
+} button_id_t;
+
+void buttons_init(void);
+void buttons_update_state(uint32_t time_ms);
+
+uint8_t buttons_get_events(button_id_t button);
+bool buttons_is_pressed(button_id_t button);
+uint32_t buttons_get_last_change_time(button_id_t button);
+
+#endif // BUTTONS_H
diff --git a/src/buzzer.c b/src/buzzer.c
new file mode 100644
index 0000000..e9a313c
--- /dev/null
+++ b/src/buzzer.c
@@ -0,0 +1,41 @@
+#include "hardware/gpio.h"
+#include "hardware/pwm.h"
+
+#include <stdint.h>
+#include <stdbool.h>
+
+#include "pinout.h"
+
+#include "buzzer.h"
+
+#define FREQ_BASE 24414063  // round(125 MHz [CPU frequency] * 100 [scaling] / 512 [PWM steps])
+
+uint m_slice_num;
+
+void buzzer_init(void)
+{
+	gpio_init(BUZZER_PIN);
+	gpio_put(BUZZER_PIN, false);
+	gpio_set_dir(BUZZER_PIN, true);
+
+	m_slice_num = pwm_gpio_to_slice_num(BUZZER_PIN);
+
+	pwm_set_clkdiv_int_frac(m_slice_num, 244, (14 << 4) / 100); // 125 MHz / 244.14 / 512 = 1 kHz
+	gpio_set_function(BUZZER_PIN, GPIO_FUNC_PWM);
+	pwm_set_wrap(m_slice_num, 512);
+	pwm_set_chan_level(m_slice_num, PWM_CHAN_B, 1 * 512 / 100);
+}
+
+void buzzer_on(uint16_t freq_hz)
+{
+	uint32_t divider_x100 = FREQ_BASE / freq_hz; // = 100 * 125e6 / 512 / freq_hz
+
+	pwm_set_clkdiv_int_frac(m_slice_num, divider_x100 / 100, divider_x100 % 100);
+	pwm_set_enabled(m_slice_num, true);
+}
+
+void buzzer_off(void)
+{
+	pwm_set_enabled(m_slice_num, false);
+	gpio_set_function(BUZZER_PIN, GPIO_FUNC_NULL);
+}
diff --git a/src/buzzer.h b/src/buzzer.h
new file mode 100644
index 0000000..23d1dff
--- /dev/null
+++ b/src/buzzer.h
@@ -0,0 +1,11 @@
+#ifndef BUZZER_H
+#define BUZZER_H
+
+#include <stdint.h>
+
+void buzzer_init(void);
+
+void buzzer_on(uint16_t freq_hz);
+void buzzer_off(void);
+
+#endif // BUZZER_H