Have things finally working with switch input and LED outputs.

Issue was due to messed up SRAM define in linker script.  IDK what
datasheet I was reading..  But I had the location and size completely
wrong.  That caused any access of SRAM to cause a hardfault of course.
First happening when popping anything to the stack.  Which also explains
why I couldn't look at the stack to figure out the last called instruciton
to point to where the issue was...

copied stm32f0xx_*.h files over from STM32F0xx_StdPeriph_Driver/inc dir

Makefile

@@ -34,7 +34,7 @@ ARCH_FLAGS=-mthumb -mcpu=cortex-m$(CORTEX_M)
 STARTUP=$(BASE)/startup/startup_ARM$(CORE).S
 
 # -Os -flto -ffunction-sections -fdata-sections to compile for code size
-CFLAGS=$(ARCH_FLAGS) $(STARTUP_DEFS) -Os -flto -ffunction-sections -fdata-sections
+CFLAGS=$(ARCH_FLAGS) $(STARTUP_DEFS) -Os -flto -ffunction-sections -fdata-sections -g
 CXXFLAGS=$(CFLAGS)
 
 # Link for code size
@@ -43,7 +43,7 @@ GC=-Wl,--gc-sections
 # Create map file
 MAP=-Wl,-Map=$(BUILD)/$(PROJ).map
 
-STARTUP_DEFS=-D__STARTUP_CLEAR_BSS -D__START=main
+STARTUP_DEFS=-D__STARTUP_CLEAR_BSS -D__START=main -D__NO_SYSTEM_INIT
 
 LDSCRIPTS=-L. -L$(BASE)/ldscripts -T nokeep.ld
 LFLAGS=$(USE_NANO) $(USE_NOHOST) $(LDSCRIPTS) $(GC) $(MAP)
@@ -57,8 +57,8 @@ CFLAGS+= $(DEFINE) $(INCLUDE)
 SOURCES=$(wildcard source/**/*.c source/*.c)
 OBJECTS=$(patsubst %.c,%.o,$(SOURCES))
 
-all: dir $(BUILD)/$(PROJ).axf $(BUILD)/$(PROJ).elf $(BUILD)/$(PROJ).hex $(BUILD)/$(PROJ).bin size 
-#all: dir $(BUILD)/$(PROJ).elf $(BUILD)/$(PROJ).hex $(BUILD)/$(PROJ).bin size 
+#all: dir $(BUILD)/$(PROJ).axf $(BUILD)/$(PROJ).elf $(BUILD)/$(PROJ).hex $(BUILD)/$(PROJ).bin size 
+all: dir $(BUILD)/$(PROJ).elf $(BUILD)/$(PROJ).hex $(BUILD)/$(PROJ).bin size 
 
 #build axf file output (basically elf with DWARF debug info)
 # $@ is shortcut for the target, $^ is shortcut for prereqs
@@ -81,6 +81,9 @@ dir:
 size:	$(BUILD)/$(PROJ).elf
 	$(SIZE) -t $^
 
+disassm:
+	arm-none-eabi-objdump build\baremetal.elf -d -g 
+
 clean: 
 	rm -rf $(BUILD)
 	rm -f $(OBJECTS)

ldscripts/nokeep.ld

@@ -7,10 +7,24 @@
  */
 MEMORY
 {
-	/*Flash always located at $08000000 */
-	/* $00000000 can be Flash, system mem, or SRAM depending on boot config */
-  FLASH (rx) : ORIGIN = 0x08000000, LENGTH = 0x20000 /* 128K */
-  RAM  (rwx) : ORIGIN = 0x10000000, LENGTH = 0x10000 /* 64K */
+	/* STM32F07x */
+	/* $0000 0000 128KB of flash/sram depending on BOOT */
+	/* $0002 0000 ~128MB of system reserved */
+	/* $0800 0000 always 128KB of flash */
+  FLASH (rx) : ORIGIN = 0x08000000, LENGTH = 128K /* 0x20000 128K */
+	/* $0802 0000 ~384MB of system reserved */
+  	/* $1FFF C800 12KB of system memory (bootloader and etc) */
+  	/* $1FFF F800 2KB of option bytes */
+  	/* $2000 0000 16KB of SRAM */
+  RAM  (rwx) : ORIGIN = 0x20000000, LENGTH = 16K /* 0x04000  16K */
+	/* $2000 4000 ~512MB of system reserved */
+	/* $4000 0000 128KB of APB perif regs & reserved */
+	/* $4002 0000 17KB of AHB1 perif regs & reserved */
+  	/* $4002 4400 ~128MB system reserved */
+  	/* $4800 0000 6KB AHB2 GPIO perif refs */
+  	/* $4800 1800 ~384MB system reserved */
+  	/* $E000 0000 1MB Cortex M0 internal peripherals */
+  	/* $E010 0000 511MB system reserved */
 }
 
 /* Linker script to place sections and symbol values. Should be used together

source/minimum.c

+
+void HardFault_Handler(void)
+{
+
+	//TODO test out this function
+	//should retrieve PC of the instruction that follows whatever caused the hardfault
+	//This didn't work for me earlier bc the stack itself was broke
+//	asm(
+//	"movs r0, #4	\n"
+//	"movs r1, lr	\n"
+//	"tst r0, r1	\n"
+//	"beq _MSP	\n"
+//	"mrs r0, psp	\n"
+//	"b _HALT	\n"
+//	"_MSP:		\n"
+//	"	mrs r0, msp	\n"
+//	"_HALT:	\n"
+//	"	ldr r1, [r0,#20]	\n"
+//	//"	bkpt #0	\n"
+//	);
+
+	while (1) {
+	}
+}
+
 #ifndef __NO_SYSTEM_INIT
 //option to create your own C library system initialization
-//Currently define __STARTUP_CLEAR_BSS when building to use
+//Currently define __STARTUP_CLEAR_BSS when building to only use
 //initialization provided by startup_ARMCM0.S that zero's the BSS section
+//To get this called in between reset routine and main function,
+//remove definition from makefile
 void SystemInit()
-{}
+{
+//	TODO Some processor initializations might be a in good order.
+//	currently just sticking with default main stack pointer (MSP)
+//	process SP is unused..
+}
 #endif
 
 //include target chip port definition library files
 #include <stm32f0xx.h>
+#include <stm32f0xx_rcc.h>
+#include <stm32f0xx_gpio.h>
 
 //include target board library files
-#include <stm32f072b_discovery.h>
+//this is junk... #include <stm32f072b_discovery.h>
+
+//Here's where the LEDs and switch are located
+//PA0 user switch
+#define SWITCH	(0U)
+
+//PC6 RED/UP
+#define RED	(6U)
+//PC7 DOWN/BLUE
+#define BLUE	(7U)
+//PC8 LEFT/YELLOW
+#define YELLOW	(8U)
+//PC9 RIGHT/GREEN
+#define GREEN	(9U)
+
+//RCC->AHBENR AHB clock enable register
+//set bit to enable clock
+#define	DMAEN	(0U)	//DMA clock
+#define	DMA2EN	(1U)	//DMA2 clock
+#define	SRAMEN	(2U)	//SRAM interface during sleep
+#define	FLITFEN	(4U)	//Flash interface during sleep
+#define	CRCEN	(6U)	//CRC clock
+#define	IOPAEN	(17U)	//IO port A
+#define	IOPBEN	(18U)	//IO port B
+#define	IOPCEN	(19U)	//IO port C
+#define	IOPDEN	(20U)	//IO port D
+#define	IOPEEN	(21U)	//IO port E
+#define	IOPFEN	(22U)	//IO port F
+#define	TSCEN	(24U)	//touch sensing controller
+
+//only one bit per pin so no extra shift needed
+void init_io()
+{
+	//Need to supply clock to i/o port before anything can be done
+	RCC->AHBENR |= ((1<<IOPAEN) | (1<<IOPCEN));
+	
+	//after reset most io registers are reset with exception of SWDIO/SWCLK for debugger
+	//This makes all other pins Input, Pushpull (no effect till set as output), Slow, no pullup/down, output reg set low.
+	//post reset, you only need to set the bits needed to set to desired config
+
+	//SET LEDs as outputs Mode register is 2bits per pin, start as off
+	//0b01 is output 2 bits per pin, 16 pins per port, fills entire 32bit MODER register
+	//need to enable pins 9-6
+	GPIOC->MODER |= ((GPIO_Mode_OUT<<(RED*2)) | (GPIO_Mode_OUT<<(BLUE*2)) | (GPIO_Mode_OUT<<(YELLOW*2)) | (GPIO_Mode_OUT<<(GREEN*2)));
+	GPIOC->MODER &= ~((GPIO_Mode_OUT<<(RED*2)) & (GPIO_Mode_OUT<<(BLUE*2)) & (GPIO_Mode_OUT<<(YELLOW*2)) & (GPIO_Mode_OUT<<(GREEN*2)));
+	
+	//GPIOC->ODR |= (0x1U<<RED);
+	//fuck it, output them all HIGH!
+	//GPIOC->ODR = 0x0000AAAA;	//blue green
+	//GPIOC->ODR = 0x00005555;	//red orange
+
+	//Switch already set to input, just enable the pullup
+	GPIOA->PUPDR |= (GPIO_PuPd_UP<<(SWITCH*2));
+
+}
 
 void main()
 {
@@ -25,9 +112,51 @@ void main()
 	//Initialize WDT, core features, etc
 	
 	//Initialize io, periphery, etc
+	//setup LED's as outputs and turn them on
+	//setup user switch as input
+	init_io();
 	
 	//Initialize board/system
 	
+	uint32_t i = 0;
+	
 	//main infinite loop
-	for (;;);
+	while(1) {
+
+		i++;
+		//to start i is zero and doesn't satisfy any checks below so all LEDs are off
+
+		//once i reaches > 2M set output data register to i
+		//This will make all LEDs turn on but not full brightness
+		//they "flicker" as i iterates
+		if ( i > 2000000 ) {
+			//mask out all but the GPIO bits
+			//a bit unfinished as we're writing to the entire GPIO register...
+			GPIOC->ODR = (i & 0x0000FFFF);
+		}
+		
+		//once i > 4M set some LEDs on solid
+		if ( i > 4000000 ) {
+			i = 0;
+			//GPIOC->ODR = 0x0000AAAA;	//blue green
+			GPIOC->ODR = 0x00005555;	//red orange
+		}
+
+		//once i > 8M reset back to 2M
+		if ( i > 8000000 ) {
+			i = 2000000;
+		}
+
+		//read in user switch
+		if ( GPIOA->IDR & (1<<SWITCH) ) {
+			//button pressed
+			i = 0;	//reset the "counter"
+			GPIOC->ODR = 0x00000000;	//all off
+
+		} else {
+			//button not pressed
+		}
+
+
+	}
 }