From a2cff11cb50dca70fb4869e6ed7188504a398e27 Mon Sep 17 00:00:00 2001
From: Sadeep Madurange <sadeep@asciimx.com>
Date: Mon, 9 Sep 2024 20:18:14 +0800
Subject: Linker script and a bunch of important fixes.

---
 Makefile        | 25 +++++++++----------------
 README.txt      |  5 +++++
 main.c          | 25 +++++++++++++++++++++++++
 openocd-due.cfg | 12 ++++++++++++
 script.ld       | 35 +++++++++++++++++++++++++++++++++++
 5 files changed, 86 insertions(+), 16 deletions(-)
 create mode 100644 README.txt
 create mode 100644 main.c
 create mode 100644 openocd-due.cfg
 create mode 100644 script.ld

diff --git a/Makefile b/Makefile
index da8a267..846d463 100644
--- a/Makefile
+++ b/Makefile
@@ -1,6 +1,6 @@
-CC = avr-gcc
-MCU = atmega328p
-TARGET = inmp
+CC = arm-none-eabi-gcc
+CPU = cortex-m3
+TARGET = due
 
 SRC = main.c
 OBJ = $(SRC:.c=.o)
@@ -8,22 +8,15 @@ OBJ = $(SRC:.c=.o)
 CFLAGS = -std=gnu99
 CFLAGS += -Os
 CFLAGS += -Wall
-CFLAGS += -mmcu=$(MCU)
-CFLAGS += -DBAUD=115200
-CFLAGS += -DF_CPU=16000000UL
-CFLAGS += -ffunction-sections -fdata-sections
+CFLAGS += -mcpu=$(CPU)
+CFLAGS += -mthumb
 
-LDFLAGS = -mmcu=$(MCU)
+LDFLAGS = -mcpu=$(CPU)
 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 $@ $<
 
@@ -31,10 +24,10 @@ elf: $(OBJ)
 	 $(CC) $(LDFLAGS) $(OBJ) -o $(TARGET).elf
 
 hex: elf
-	 avr-objcopy $(HEX_FLAGS) $(TARGET).elf $(TARGET).hex
+	 arm-none-eabi-objcopy $(HEX_FLAGS) $(TARGET).elf $(TARGET).hex
 
-upload: hex
-	 avrdude $(AVRDUDE_FLAGS) flash:w:$(TARGET).hex:i
+#upload: hex
+#     openocd -f openocd-due.cfg -c "program $(TARGET) verify reset exit"
 
 .PHONY: clean
 
diff --git a/README.txt b/README.txt
new file mode 100644
index 0000000..ab93862
--- /dev/null
+++ b/README.txt
@@ -0,0 +1,5 @@
+Compile and upload
+
+$ arm-none-eabi-gcc -mcpu=cortex-m3 -mthumb -o a.elf main.c
+$ arm-none-eabi-objcopy -O ihex -j .text -j .data a.elf a.hex
+$ avrdude -c arduino -p atmel_sam3x8e -v -b 115200 -U flash:w:a.hex
diff --git a/main.c b/main.c
new file mode 100644
index 0000000..137e093
--- /dev/null
+++ b/main.c
@@ -0,0 +1,25 @@
+#define PIOC_PER  *((volatile unsigned int *) 0x400E1200U)
+#define PIOC_OER  *((volatile unsigned int *) 0x400E1210U)
+#define PIOC_IDR  *((volatile unsigned int *) 0x400E1244U)
+#define PIOC_CODR *((volatile unsigned int *) 0x400E1234U)
+#define PIOC_IFDR *((volatile unsigned int *) 0x400E1224U)
+#define PIOC_MDDR *((volatile unsigned int *) 0x400E1254U)
+#define PIOC_ODSR *((volatile unsigned int *) 0x400E1238U)
+#define PIOC_PUDR *((volatile unsigned int *) 0x400E1260U)
+#define PIOC_OWDR *((volatile unsigned int *) 0x400E12A4U)
+
+int main(void)
+{
+	PIOC_PER = 0x00000001;
+	PIOC_OER = 0x00000001;
+	PIOC_IDR = 0x00000001;
+	PIOC_CODR = 0x00000001;
+	PIOC_IFDR = 0x00000001;
+	PIOC_MDDR = 0x00000001;
+	PIOC_PUDR = 0x00000001;
+	PIOC_OWDR = 0x00000001;
+
+	PIOC_ODSR = 0x00000001;
+
+	return 0;
+}
diff --git a/openocd-due.cfg b/openocd-due.cfg
new file mode 100644
index 0000000..8fba185
--- /dev/null
+++ b/openocd-due.cfg
@@ -0,0 +1,12 @@
+source [find interface/stlink.cfg]
+
+#transport type SWD
+transport select hla_swd
+
+#swd frequency
+adapter speed 1800
+
+#sam3x8e cpuid
+set CPUTAPID 0x2ba01477
+
+source [find target/at91sam3ax_8x.cfg]
diff --git a/script.ld b/script.ld
new file mode 100644
index 0000000..e8b0bb1
--- /dev/null
+++ b/script.ld
@@ -0,0 +1,35 @@
+MEMORY
+{
+	rom (rx)  : ORIGIN = 0x00080000, LENGTH = 0x00080000
+	ram (rwx) : ORIGIN = 0x20000000, LENGTH = 0x00010000
+}
+
+SECTIONS
+{
+	. = ALIGN(4);
+	.text :
+	{
+		KEEP(*(.vectors .vectors.*))
+		*(.text*)
+		*(.rodata*)
+	} > rom
+
+	. = ALIGN(4);
+	.data :
+	{
+		*(.data*);
+	} > ram AT >rom
+
+	. = ALIGN(4);
+	.bss (NOLOAD) :
+	{
+		__bss_start__ = . ;
+		*(.bss*)
+		*(COMMON)
+		__bss_end__ = . ;
+	} > ram
+
+	_end = . ;
+	__end__ = _end ;
+	end = _end;
+}
-- 
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