Initial commit

.gitignore

+*.o
+*.hex
+*.elf

Makefile

+# Name of compilation target
+TARGET		= main
+
+# Bin paths
+GCC_BIN		= avr-gcc
+OBJCOPY_BIN	= avr-objcopy
+AVRDUDE_BIN	= avrdude
+
+# MCU and programmer settings
+MCU			= atmega328p
+PROGRAMMER	= arduino
+BAUDRATE	= 115200
+PORT		= /dev/ttyACM0
+
+# Arguments for compilation, linking, conversion to hex, and uploading
+C_FLAGS			= -Os -g -Wall -DF_CPU=16000000 -mmcu=$(MCU) -std=gnu99
+LD_FLAGS		= -lm -Os -g -Wl,--gc-sections -mmcu=$(MCU)
+OBJCOPY_FLAGS	= -O ihex -R .eeprom
+AVRDUDE_FLAGS	= -p $(MCU) -c $(PROGRAMMER) -b $(BAUDRATE) -P $(PORT)
+
+# Make targets
+all: $(TARGET).hex
+
+clean:
+	rm -f $(TARGET).elf *.o *.hex
+
+%.o: %.c
+	$(GCC_BIN) -c $(C_FLAGS) $< -o $@
+
+$(TARGET).elf: $(TARGET).o
+	$(GCC_BIN) $(LD_FLAGS) $(TARGET).o -o $(TARGET).elf
+
+$(TARGET).hex: $(TARGET).elf
+	$(OBJCOPY_BIN) $(OBJCOPY_FLAGS) $(TARGET).elf $(TARGET).hex
+
+upload:	$(TARGET).hex
+	$(AVRDUDE_BIN) $(AVRDUDE_FLAGS) -U flash:w:$(TARGET).hex

README.md

+# Fencing Test Box v3
+
+Software for the third version of my electronic test box for fencing equipment.
+Runs on the [ATmega328/P](https://www.microchip.com/wwwproducts/en/ATmega328P) microcontroller.
+
+#### See also
+
+* [Fencing Test Box v2](https://ant.sr/test-box) ("prior art")
+
+## Build
+
+Use these `make` invocations as needed:
+
+* `make` - compile
+* `make upload` - write to AVR flash
+* `make clean` - remove built artifacts (ensures next `make` will recompile)

blink.c

+#include <avr/io.h>
+#include <util/delay.h>
+
+#define STROBE_DURATION_MS 20
+
+/* This file is just placeholder stuff. It has nothing to do with testing. */
+
+void delay(int duration) {
+    duration = duration / 10;
+    while (duration--) {
+        _delay_ms(10);
+    }
+}
+
+void blink_once(int duration) {
+        /* Output High */
+        PORTB |= _BV(PORTB5);
+
+        /* Wait */
+        delay(duration);
+
+        /* Output Low */
+        PORTB &= ~_BV(PORTB5);
+}
+
+void strobe_pulse() {
+    /* Blinking pattern. Looks neat. */
+    for (int j = 5; j < 10; j++) {
+        for (int i = 1; i < j; i++) {
+            blink_once(STROBE_DURATION_MS * i);
+            delay(STROBE_DURATION_MS * i);
+        }
+        for (int i = j; i > 0; i--) {
+            blink_once(STROBE_DURATION_MS * i);
+            delay(STROBE_DURATION_MS * i);
+        }
+    }
+}

main.c

+#include "blink.c"
+
+void init() {
+    /* Make Pin 5 of PORTB an output. */
+    DDRB |= _BV(DDB5);
+}
+
+void loop() {
+    /* Strobe forever */
+    strobe_pulse();
+}
+
+int main(void) {
+    init();
+    while (1) {
+        loop();
+    }
+}
+