Added sample UART program

Software/hello-atmega328p-usbasp/main.c

@@ -0,0 +1,92 @@
+#include <stdio.h>
+#include <ctype.h>
+#include <avr/io.h>
+#include <util/delay.h>
+
+#define BAUD 9600
+#include <util/setbaud.h>
+
+void uart_init();
+int uart_putchar(char c, FILE *stream);
+int uart_getchar(FILE *stream);
+void uart_send(char c);
+char uart_recv(void);
+
+FILE uart_output = FDEV_SETUP_STREAM(uart_putchar, NULL, _FDEV_SETUP_WRITE);
+FILE uart_input = FDEV_SETUP_STREAM(NULL, uart_getchar, _FDEV_SETUP_READ);
+
+int main(void)
+{
+    // Configure PB5 as an output using the Port B Data Direction Register (DDRB)
+    DDRB |= _BV(DDB0);
+
+    // init serial interface
+    uart_init();
+
+    // redirect standard output
+    stdout = &uart_output;
+    stdin = &uart_input;
+
+    // Loop forever
+    while (1)
+    {
+        // Set PB5 high using the Port B Data Register (PORTB)
+        PORTB |= _BV(PORTB0);
+
+        // Wait 500ms
+        _delay_ms(200);
+
+        // Set PB5 low using the Port B Data Register (PORTB)
+        PORTB &= ~_BV(PORTB0);
+
+        // Wait 500ms
+        _delay_ms(200);
+
+        // Wait for input from serial
+        getc(stdin);
+
+        // Print hello
+        printf("Hello World!\n");        
+    }
+}
+
+void uart_init()
+{
+  UBRR0H = UBRRH_VALUE;
+  UBRR0L = UBRRL_VALUE;
+  #if USE_2X
+  UCSR0A |= (1 << U2X0);
+  #else
+  UCSR0A &= ~(1 << U2X0);
+  #endif
+
+  UCSR0C = _BV(UCSZ01) | _BV(UCSZ00); /* 8-bit data, async, no parity, 1 stop bit */
+  UCSR0B = _BV(RXEN0) | _BV(TXEN0);   /* Enable RX and TX */
+}
+
+int uart_putchar(char c, FILE *stream)
+{
+  if (c == '\n')
+  {
+    uart_putchar('\r', stream);
+  }
+  uart_send(c);
+  return 0;
+}
+
+int uart_getchar(FILE *stream)
+{
+  return uart_recv();
+}
+
+void uart_send(char c) 
+{
+  loop_until_bit_is_set(UCSR0A, UDRE0);
+  UDR0 = c;
+}
+
+char uart_recv(void) 
+{
+  loop_until_bit_is_set(UCSR0A, RXC0);
+  return UDR0;  
+}

Software/hello-atmega328p-usbasp/makefile

@@ -0,0 +1,82 @@
+NAME := main
+BUILD_FOLDER=build
+HEX := $(BUILD_FOLDER)/$(NAME).hex
+OUT := $(BUILD_FOLDER)/$(NAME).out
+MAP := $(BUILD_FOLDER)/$(NAME).map
+SOURCES := $(wildcard *.c)
+HEADERS := $(wildcard *.h)
+OBJECTS := $(patsubst %.c,$(BUILD_FOLDER)/%.o,$(SOURCES))
+
+MCU := atmega328p
+MCU_AVRDUDE := m328p
+PARTNO := usbasp
+DEVICE := usb
+AVRDUDE_FLAGS := -v -B 5
+
+CC := avr-gcc
+OBJCOPY := avr-objcopy
+SIZE := avr-size -A
+
+CFLAGS := -Wall -pedantic -mmcu=$(MCU) -std=c99 -g -Os -DF_CPU=1000000UL
+
+# Picocom settings
+PICOCOM_BINARY=picocom
+PICOCOM_FLAGS=-fn
+TERM_SPEED=-b9600
+
+# efuse 11111101
+# efuse bits 7..3 = 11111 (default)
+# efuse bits 2..0 = 101 (BOD 2.7V)
+EFUSE := 0xfd
+
+# hfuse 11010111
+# hfuse bit 7 = 1 (external reset enabled)
+# hfuse bit 6 = 1 (debugWire disabled)
+# hfuse bit 5 = 0 (SPI programming enabled)
+# hfuse bit 4 = 1 (watchdog timer always on)
+# hfuse bit 3 = 0 (retain EEPROM)
+# hfuse bits 2..1 = 11 (bootloader size 256 - no bootloader)
+# hfuse bit 0 = 1 (boot reset vector unprogrammed)
+HFUSE := 0xd7
+
+# lfuse 01100010
+# lfuse bit 7 = 0 (clock divide by 8 enabled)
+# lfuse bit 6 = 1 (clock output disabled)
+# lfuse bits 5..4 = 10 (maximum startup time)
+# lfuse bits 3..0 = 0010 (internal RC oscillator at 1MHz)
+LFUSE := 0x62
+
+all: $(HEX) $(BUILD_FOLDER)
+
+clean:
+	rm -rf $(HEX) $(OUT) $(MAP) $(OBJECTS) $(BUILD_FOLDER)
+
+$(BUILD_FOLDER):
+	mkdir $(BUILD_FOLDER)
+
+flash: $(HEX)
+	avrdude $(AVRDUDE_FLAGS) -c $(PARTNO) -p $(MCU_AVRDUDE) -P $(DEVICE) -U flash:w:$(HEX)
+
+fuses:
+	avrdude $(AVRDUDE_FLAGS) -c $(PARTNO) -p $(MCU_AVRDUDE) -P $(DEVICE) -U efuse:w:$(EFUSE):m -U hfuse:w:$(HFUSE):m -U lfuse:w:$(LFUSE):m
+
+terminal:
+	$(PICOCOM_BINARY) $(PICOCOM_FLAGS) $(TERM_SPEED) /dev/tty.usbserial-D309UUZL
+
+$(HEX): $(OUT)
+	$(OBJCOPY) -R .eeprom -O ihex $< $@
+
+$(OUT): $(OBJECTS)
+	$(CC) $(CFLAGS) -o $@ -Wl,-Map,$(MAP) $^
+	@echo
+	@$(SIZE) $@
+	@echo
+
+$(BUILD_FOLDER)/%.o: %.c $(HEADERS) $(BUILD_FOLDER)
+	$(CC) $(CFLAGS) -c -o $@ $<
+
+$(BUILD_FOLDER)/%.pp: %.c $(BUILD_FOLDER)
+	$(CC) $(CFLAGS) -E -o $@ $<
+
+$(BUILD_FOLDER)/%.ppo: %.c $(BUILD_FOLDER)
+	$(CC) $(CFLAGS) -E $<