From d41e70ce3463f6b239da415c5d69773fce55f9e9 Mon Sep 17 00:00:00 2001
From: Sadeep Madurange <sadeep@asciimx.com>
Date: Sat, 2 Nov 2024 15:18:22 +0800
Subject: Initial commit.

---
 .gitignore |  9 +++++++++
 Makefile   | 41 +++++++++++++++++++++++++++++++++++++++++
 main.c     | 25 +++++++++++++++++++++++++
 3 files changed, 75 insertions(+)
 create mode 100644 .gitignore
 create mode 100644 Makefile
 create mode 100644 main.c

diff --git a/.gitignore b/.gitignore
new file mode 100644
index 0000000..596a14b
--- /dev/null
+++ b/.gitignore
@@ -0,0 +1,9 @@
+# C
+**/*.o
+**/*.elf
+**/*.hex
+**/*.out
+
+# Vim
+*.swp
+*.core
diff --git a/Makefile b/Makefile
new file mode 100644
index 0000000..27092b1
--- /dev/null
+++ b/Makefile
@@ -0,0 +1,41 @@
+CC = avr-gcc
+MCU = atmega328p
+TARGET = blink
+
+SRC = main.c
+OBJ = $(SRC:.c=.o)
+
+CFLAGS = -std=gnu99
+CFLAGS += -Os
+CFLAGS+= -Wall
+CFLAGS+= -mmcu=$(MCU)
+CFLAGS+= -DF_CPU=16000000UL
+CFLAGS+= -ffunction-sections -fdata-sections
+
+LDFLAGS = -mmcu=$(MCU)
+LDFLAGS += -Wl,--gc-sections
+
+HEX_FLAGS = -O ihex
+HEX_FLAGS += -j .text -j .data
+
+AVRDUDE_FLAGS = -p $(MCU)
+AVRDUDE_FLAGS += -c arduino
+AVRDUDE_FLAGS += -P /dev/cuaU0
+AVRDUDE_FLAGS += -D -U
+
+%.o: %.c
+	 $(CC) $(CFLAGS) -c -o $@ $<
+
+elf: $(OBJ)
+	 $(CC) $(LDFLAGS) $(OBJ) -o $(TARGET).elf
+
+hex: elf
+	 avr-objcopy $(HEX_FLAGS) $(TARGET).elf $(TARGET).hex
+
+upload: hex
+	 avrdude $(AVRDUDE_FLAGS) flash:w:$(TARGET).hex:i
+
+.PHONY: clean
+
+clean:
+	 rm *.o *.elf *.hex 
diff --git a/main.c b/main.c
new file mode 100644
index 0000000..aed9465
--- /dev/null
+++ b/main.c
@@ -0,0 +1,25 @@
+#include <avr/io.h>
+#include <avr/interrupt.h>
+
+int main(void)
+{
+	DDRB |= (1 << DDB5);
+
+	TCCR1A = 0;
+	TCNT1 = 65535 - (F_CPU / 1024);
+	TCCR1B = (1 << CS10) | (1 << CS12);
+	TIMSK1 = (1 << TOIE1);
+
+	sei();
+
+	for (;;)
+		;
+
+	return 0;
+}
+
+ISR(TIMER1_OVF_vect)
+{
+	PORTB ^= (1 << 5);
+	TCNT1 = 65535 - (F_CPU / 1024);
+}
-- 
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