start working on the speaker arduino code

Makefile

@@ -0,0 +1,11 @@
+CC 	= avr-gcc
+CFLAGS	= -O2 -Wall -Wextra -Werror -mmcu=atmega328p
+OBJCOPY	= avr-objcopy
+
+all:
+	${CC} ${CFLAGS} main.c
+	${OBJCOPY} -j .text -j .data -O ihex a.out main.hex
+	rm -f a.out
+
+flash: all
+	avrdude -p atmega328p -c arduino -P /dev/ttyACM0 -b 115200 -U flash:w:main.hex:i

main.c

@@ -0,0 +1,79 @@
+/*
+ *  EEL4746C - AVR Piano - Speaker Section
+ *  speaker is connected to PD2 and ground
+ *  buttons are connected to PB0-5, PC0-5, PD3-7
+ *  the LCD Arduino UNO is connected to TX/RX (PD0/1)
+ */
+
+#include <avr/io.h>
+#include <avr/interrupt.h>
+
+#define F_CPU	16000000UL
+#include <util/delay.h>
+
+#define P_RX	0
+#define P_TX	1
+#define P_SPKR	2
+
+unsigned short freqs[] = {
+	100,
+	200,
+	250,
+	300,
+	350,
+	400,
+	500,
+	600,
+	700,
+	750,
+	1000,
+	1250,
+	1500,
+	1750,
+	2000,
+	3000,
+	4000,
+	5000,
+	6000,
+	7000,
+	8000
+};
+unsigned char note = 0;
+unsigned char buttonpressed = 1;
+
+int
+main(void)
+{
+	DDRB = 0x00;
+	DDRC = 0x00;
+	DDRD = (1 << P_TX) | (1 << P_SPKR);
+
+	PCMSK0 = 0xFF;
+	PCMSK1 = 0xFF;
+	PCMSK2 = ~(1 | (1 << 1) | (1 << 2));
+	PCICR = (1 << PCIE0) | (1 << PCIE1) | (1 << PCIE2);
+
+	sei();
+
+	//for (;;);
+	for (unsigned char n = 0;; n = (n + 1) % 2) {
+		if (!buttonpressed) continue;
+		_delay_us(71.43);
+		PORTD ^= 1 << P_SPKR;
+	}
+}
+
+ISR (PCINT0_vect)
+{
+
+}
+
+ISR (PCINT1_vect)
+{
+
+}
+
+ISR (PCINT2_vect)
+{
+
+}