diff --git a/hardware.h b/hardware.h
index 04e11a6..14d56b1 100644
--- a/hardware.h
+++ b/hardware.h
@@ -14,8 +14,8 @@
 #define TFT_RST		26
 
 // PS/2 keyboard
-#define KBD_DATA	14
-#define KBD_IRQ		0
+#define KBD_DATA	34
+#define KBD_IRQ		35
 
 // SPI-RAM
 #undef SPIRAM_CS
@@ -26,6 +26,8 @@
 
 // sound
 #define DAC_SOUND	25
+#define PWM_SOUND	25
+#define PWM_DUTY	20	// 20/1024 -> volume
 
 bool hardware_reset();
 void hardware_init(class CPU &);
diff --git a/sound_pwm.cpp b/sound_pwm.cpp
new file mode 100644
index 0000000..7ac2b5f
--- /dev/null
+++ b/sound_pwm.cpp
@@ -0,0 +1,54 @@
+#include "sound_pwm.h"
+#include "hardware.h"
+
+#if defined(ESP32)
+#include <driver/ledc.h>
+
+#define CHANNEL		LEDC_CHANNEL_0
+#define TIMER		LEDC_TIMER_0
+#define SPEED_MODE	LEDC_HIGH_SPEED_MODE
+
+void PWM::begin(unsigned gpio) {
+	ledc_timer_config_t timer_conf;
+  	timer_conf.duty_resolution = LEDC_TIMER_10_BIT;
+  	timer_conf.freq_hz = 440;
+  	timer_conf.speed_mode = SPEED_MODE;
+  	timer_conf.timer_num = TIMER;
+  	ESP_ERROR_CHECK(::ledc_timer_config(&timer_conf));
+
+  	ledc_channel_config_t ledc_conf;
+  	ledc_conf.channel = CHANNEL;
+  	ledc_conf.duty = 0;
+  	ledc_conf.gpio_num = gpio;
+  	ledc_conf.intr_type = LEDC_INTR_DISABLE;
+  	ledc_conf.speed_mode = SPEED_MODE;
+  	ledc_conf.timer_sel = TIMER;
+  	ESP_ERROR_CHECK(::ledc_channel_config(&ledc_conf));
+}
+
+void PWM::set_duty(unsigned duty) {
+	ESP_ERROR_CHECK(::ledc_set_duty(SPEED_MODE, CHANNEL, duty));
+	ESP_ERROR_CHECK(::ledc_update_duty(SPEED_MODE, CHANNEL));
+}
+
+void PWM::stop() {
+	set_duty(0);
+}
+
+void PWM::set_freq(unsigned freq) {
+      ESP_ERROR_CHECK(::ledc_set_freq(SPEED_MODE, TIMER, freq));
+}
+
+#else
+void PWM::begin(unsigned gpio) {
+}
+
+void PWM::start(unsigned duty) {
+}
+
+void PWM::stop() {
+}
+
+void PWM::set_freq(unsigned freq) {
+}
+#endif
diff --git a/sound_pwm.h b/sound_pwm.h
new file mode 100644
index 0000000..e4d87e4
--- /dev/null
+++ b/sound_pwm.h
@@ -0,0 +1,12 @@
+#ifndef __SOUND_PWM_H__
+#define __SOUND_PWM_H__
+
+class PWM {
+public:
+	void begin(unsigned gpio);
+	void set_duty(unsigned duty);
+	void stop();
+	void set_freq(unsigned freq);
+};
+
+#endif