feat(ex01): ex01 is complete

ex01/Makefile

@@ -0,0 +1,43 @@
+# Makefile
+MCU=atmega328p
+F_CPU=16000000
+CC=avr-gcc
+OBJCOPY=avr-objcopy
+CFLAGS=-std=c99 -Wall -Wextra -g -Os -mmcu=$(MCU) -DF_CPU=$(F_CPU) -Iinclude
+TARGET=main
+SERIAL=-P /dev/ttyUSB0 -b 115200
+
+
+SRC_DIR=.
+OBJ_DIR=build
+
+SRC_FILES=main.c utils.c
+OBJ_FILES=$(patsubst %.c,%.o,$(SRC_FILES))
+
+SRC=$(addprefix $(SRC_DIR)/,$(SRC_FILES))
+OBJ=$(addprefix $(OBJ_DIR)/,$(OBJ_FILES))
+
+all: flash
+
+re: fclean all
+
+fclean: clean
+clean:
+	rm -rf $(OBJ_DIR)
+	rm -f $(TARGET).hex
+
+hex: $(TARGET).hex
+
+flash: hex
+	avrdude -p $(MCU) -c arduino -U flash:w:$(TARGET).hex:i $(SERIAL) 
+
+$(OBJ_DIR)/$(TARGET).bin: $(OBJ)
+	$(CC) $(CFLAGS) $(OBJ) -o $@
+
+$(OBJ_DIR)/%.o: $(SRC_DIR)/%.c 
+	mkdir -p $(shell dirname $@)
+	$(CC) $(CFLAGS) -c $< -o $@
+
+
+$(TARGET).hex: $(OBJ_DIR)/$(TARGET).bin
+	$(OBJCOPY) -j .text -j .data -O ihex $< $@

ex01/include/mystd.h

@@ -0,0 +1,15 @@
+#ifndef MYSTDINT_H
+#define MYSTDINT_H
+
+typedef unsigned int uint16_t;
+typedef signed int	 int16_t;
+
+typedef unsigned char uint8_t;
+typedef signed char	  int8_t;
+
+typedef uint8_t bool;
+
+#define true  (1)
+#define false (0)
+
+#endif /* MYSTDINT_H */

ex01/include/utils.h

@@ -0,0 +1,8 @@
+#ifndef UTILS_H
+#define UTILS_H
+
+#include "mystd.h"
+
+void delay_ms(uint16_t count);
+
+#endif /* UTILS_H */

ex01/main.c

@@ -0,0 +1,44 @@
+#include <avr/io.h>
+#include "mystd.h"
+#include "utils.h"
+
+#define D1		  PORTB0
+#define D2		  PORTB1
+#define D3		  PORTB2
+#define D4		  PORTB4
+
+#define PRESCALER 256
+#define TIMER_FREQ (F_CPU / PRESCALER)
+
+
+// at a high level:
+// Set the OC1B (PB2) pin as output
+// set the TIMER1 mode to COMPARE (CTC)
+// say to compare against OC1A
+// set the value to be compated at X count
+// say the presacler for the timer is 512
+//
+// all these information are on page ~140
+void timer1_init(void) {
+	// Set PB2 (OC1B) as output
+	DDRB   |= _BV(PB2);
+
+	// CTC mode (WGM12 = 1)
+	TCCR1B |= _BV(WGM12);
+
+	// Toggle OC1B on compare match (COM1B0 = 1)
+	TCCR1A |= _BV(COM1B0);
+
+	// Set compare values
+	OCR1A	= TIMER_FREQ / 2;
+
+	// Start timer with prescaler 256 (CS12)
+	TCCR1B |= _BV(CS12);
+}
+
+int main(void) {
+	timer1_init();
+	while (1) {
+	}
+}
+

ex01/utils.c

@@ -0,0 +1,19 @@
+#include "utils.h"
+
+// this just burns cycles.
+// the volatile is important, it means that the cpu can't optimize any
+// read/writes for the value
+static inline void spin_loop(volatile uint16_t counts) {
+	while (counts)
+		counts--;
+}
+
+void delay_ms(uint16_t ms) {
+	while (ms) {
+		// this value was taken using a delay of 500ms, and just recording the led
+		// blinking. it seems to be high enough such that each loop of delay_loop
+		// takes 1ms :D
+		spin_loop((F_CPU) / 5000);
+		ms--;
+	}
+}