From cd8984fa29a0059605512402e876f70d615d9227 Mon Sep 17 00:00:00 2001
From: Maix0 <39835848+Maix0@users.noreply.github.com>
Date: Mon, 13 Apr 2026 14:19:59 +0200
Subject: [PATCH] feat(ex03): full ex03

---
 ex03/Makefile | 53 +++++++++++++++++++++++++++++++++++++++++++++++++++
 ex03/main.c   | 27 ++++++++++++++++++++++++++
 2 files changed, 80 insertions(+)
 create mode 100644 ex03/Makefile
 create mode 100644 ex03/main.c

diff --git a/ex03/Makefile b/ex03/Makefile
new file mode 100644
index 0000000..d0f7e1f
--- /dev/null
+++ b/ex03/Makefile
@@ -0,0 +1,53 @@
+AVR_LIBC_DIR=/tmp/avr-libc
+
+# Makefile
+MCU=atmega328p
+F_CPU=16000000
+CC=avr-gcc
+OBJCOPY=avr-objcopy
+CFLAGS=-nostdlib -std=c99 -Wall -Wextra -g -Os -mmcu=$(MCU) -DF_CPU=$(F_CPU) -I. -I$(AVR_LIBC_DIR)/include
+TARGET=main
+SERIAL=-P /dev/ttyUSB0 -b 115200
+
+
+SRC_DIR=.
+OBJ_DIR=build
+
+SRC_FILES=main.c
+OBJ_FILES=$(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 $(AVR_LIBC_DIR)/.CACHETAG
+	mkdir -p $(shell dirname $@)
+	$(CC) $(CFLAGS) -c $< -o $@
+
+
+$(TARGET).hex: $(OBJ_DIR)/$(TARGET).bin
+	$(OBJCOPY) -j .text -j .data -O ihex $< $@
+
+$(AVR_LIBC_DIR)/.CACHETAG:
+	rm -rf $(AVR_LIBC_DIR)
+	git clone --depth=1 https://github.com/avrdudes/avr-libc/ $(AVR_LIBC_DIR)
+	cd $(AVR_LIBC_DIR) && ./bootstrap
+	cd $(AVR_LIBC_DIR) && ./configure --build=`./config.guess` --host=avr
+	cd $(AVR_LIBC_DIR) && make -j
+	touch $(AVR_LIBC_DIR)/.CACHETAG
diff --git a/ex03/main.c b/ex03/main.c
new file mode 100644
index 0000000..fab1d0b
--- /dev/null
+++ b/ex03/main.c
@@ -0,0 +1,27 @@
+#include <avr/io.h>
+#include <util/delay.h>
+
+#include <stdbool.h>
+
+#define LED_PORT PORTB0
+#define BTN_PORT PIND2
+
+int main(void) {
+  // set pin to output
+  DDRB |= (_BV(LED_PORT));
+
+  bool led_state = false;
+  bool prev = (PIND & _BV(BTN_PORT));
+  while (true) {
+    bool cur = (PIND & _BV(BTN_PORT));
+    if (prev && !cur) {
+      led_state = !led_state;
+      if (led_state)
+        PORTB |= (_BV(LED_PORT));
+      else
+        PORTB &= ~(_BV(LED_PORT));
+    }
+    prev = cur;
+    _delay_ms(20.f);
+  }
+}