fix merge

sound_pwm.cpp

@@ -0,0 +1,16 @@
+#include <Arduino.h>
+#include "sound_pwm.h"
+
+static unsigned gpio;
+
+void PWM::begin(unsigned gpio) {
+	::gpio = gpio;
+}
+
+void PWM::stop() {
+	noTone(gpio);
+}
+
+void PWM::start(unsigned freq) {
+	tone(gpio, freq);
+}

sound_pwm.h

@@ -0,0 +1,11 @@
+#ifndef __SOUND_PWM_H__
+#define __SOUND_PWM_H__
+
+class PWM {
+public:
+	void begin(unsigned gpio);
+	void stop();
+	void start(unsigned freq);
+};
+
+#endif