6 files changed, 115 insertions, 10 deletions
diff --git a/sw-avr/rom-loader/main.c b/sw-avr/rom-loader/main.c
index b178c06..784afb6 100644
--- a/sw-avr/rom-loader/main.c
+++ b/sw-avr/rom-loader/main.c
@@ -1,6 +1,38 @@
 #include <avr/io.h>
 
+#include "usart.h"
+#include "pinmap.h"
+
+// TODO: remove
+#include <util/delay.h>
+
+
+inline void io_init(void)
+{
+    ADDRL_DDR |= (_BV(ADDRL_bitE) | _BV(ADDRL_bitD));
+    ADDRL_DDR |= (0x7<<ADDRL_bitA0); // 3 bits
+
+    ADDRH_DDR |= (_BV(ADDRH_bitE) | _BV(ADDRH_bitD));
+    ADDRH_DDR |= (0x7<<ADDRH_bitA0);
+
+    // all output
+    DATA_DDR = 0xFF;
+}
+
 int main(void)
 {
-    return;
+    io_init();
+    usart_init();
+
+    // TODO: remove
+    DATA_PORT |= _BV(1);
+
+    while (1) {
+        DATA_PORT ^= _BV(1);
+        _delay_ms(500);
+
+        usart_send('c');
+    }
+
+    return 0;
 }
diff --git a/sw-avr/rom-loader/makefile b/sw-avr/rom-loader/makefile
index e68174f..85222c8 100644
--- a/sw-avr/rom-loader/makefile
+++ b/sw-avr/rom-loader/makefile
@@ -1,17 +1,24 @@
-CC=avr-gcc
-CARGS=-Wall -mmcu=atmega328p -D__AVR_ATmega328p__ -Os -I.
+SOURCES := main.c usart.c
+OBJECTS := $(patsubst %.c,%.o,$(SOURCES))
 
-SOURCES=main.c
+CFLAGS  := -Wall -mmcu=atmega328p -Os -I. \
+            -D__AVR_ATmega328p__ -DF_CPU=1000000UL -DBAUD=9600
+LDFLAGS := 
 
 .PHONY: all flash clean
-all: rom-loader.bin
+all: rom-loader.hex
 
-flash: rom-loader.bin
-	avrdude -c usbasp -p atmega328p
+flash: rom-loader.hex
+	avrdude -c usbasp -p atmega328p -U flash:w:$<
 
 clean:
-	rm rom-loader.bin
+	rm -f *.bin *.hex *.o
 
-rom-loader.bin: $(SOURCES)
-	$(CC) $(CARGS) $< -o $@
+rom-loader.hex: rom-loader.bin
+	avr-objcopy -R .eeprom -O ihex $< $@
 
+rom-loader.bin: $(OBJECTS)
+	avr-gcc $(CFLAGS) $(OBJECTS) -o $@ $(LDFLAGS)
+
+%.o: %.c
+	avr-gcc $(CFLAGS) $< -c -o $@ $(LDFLAGS)
diff --git a/sw-avr/rom-loader/pinmap.h b/sw-avr/rom-loader/pinmap.h
new file mode 100644
index 0000000..1149feb
--- /dev/null
+++ b/sw-avr/rom-loader/pinmap.h
@@ -0,0 +1,19 @@
+#ifndef PINMAP_H
+#define PINMAP_H
+
+#define ADDRL_DDR   DDRC
+#define ADDRL_PORT  PORTC
+#define ADDRL_bitE  3
+#define ADDRL_bitD  4
+#define ADDRL_bitA0 0
+
+#define ADDRH_DDR   DDRD
+#define ADDRH_PORT  PORTD
+#define ADDRH_bitE  7
+#define ADDRH_bitD  3
+#define ADDRH_bitA0 4
+
+#define DATA_DDR  DDRB
+#define DATA_PORT PORTB
+
+#endif
diff --git a/sw-avr/rom-loader/rom-loader.bin b/sw-avr/rom-loader/rom-loader.bin
deleted file mode 100755
index 1feb241..0000000
--- a/sw-avr/rom-loader/rom-loader.bin
+++ /dev/null
diff --git a/sw-avr/rom-loader/usart.c b/sw-avr/rom-loader/usart.c
new file mode 100644
index 0000000..5637d4f
--- /dev/null
+++ b/sw-avr/rom-loader/usart.c
@@ -0,0 +1,37 @@
+#include "usart.h"
+
+#include <avr/io.h>
+#include <util/setbaud.h>
+
+void usart_init(void)
+{
+    // automated by util/setbaud.h
+    UBRR0H = UBRRH_VALUE;
+    UBRR0L = UBRRL_VALUE;
+
+#if USE_2X
+    UCSR0A |= _BV(U2X0);
+#else
+    UCSR0A &= ~(_BV(U2X0));
+#endif
+
+    // 8 bit data
+    UCSR0C = _BV(UCSZ01) | _BV(UCSZ00);
+
+    // enable TX and RX pins
+    UCSR0B = _BV(RXEN0) | _BV(TXEN0);
+}
+
+void usart_send(uint8_t c)
+{
+    UDR0 = c;    
+    // wait until transmission ready
+    loop_until_bit_is_set(UCSR0A, TXC0); 
+}
+
+uint8_t usart_recv(void)
+{
+    // wait until data exists
+    loop_until_bit_is_set(UCSR0A, RXC0);
+    return UDR0;
+}
diff --git a/sw-avr/rom-loader/usart.h b/sw-avr/rom-loader/usart.h
new file mode 100644
index 0000000..f7d8806
--- /dev/null
+++ b/sw-avr/rom-loader/usart.h
@@ -0,0 +1,10 @@
+#ifndef USART_H
+#define USART_H
+
+#include <stdint.h>
+
+void usart_init(void);
+void usart_send(uint8_t c);
+uint8_t usart_recv(void);
+
+#endif