; Minimum startup from startup_stm32f10x_cl.s
; Author: heth@mercantec.dk
; Revision 1 - 29-aug-2011

;Define Stack
Stack_Size      EQU     0x00000200

                AREA    STACK, NOINIT, READWRITE, ALIGN=3
Stack_Mem       SPACE   Stack_Size
__initial_sp


;Define Heapsize
Heap_Size       EQU     0x00000000

                AREA    HEAP, NOINIT, READWRITE, ALIGN=3
__heap_base
Heap_Mem        SPACE   Heap_Size
__heap_limit


                     
		AREA    RESET, DATA, READONLY
				EXPORT  __initial_sp
                EXPORT  __heap_base
                EXPORT  __heap_limit
		       
			    EXPORT  __Vectors
                EXPORT  __Vectors_End
                EXPORT  __Vectors_Size
		 		
				PRESERVE8
                THUMB  ; Use THUMB instruction set  

; Vector Table Mapped to Address 0 at Reset
__Vectors       DCD     __initial_sp              ; Top of Stack
                DCD     Reset_Handler             ; Reset Handler
__Vectors_End

__Vectors_Size 	EQU 	__Vectors_End - __Vectors

				; Not nessesary HeTh IMPORT  __use_two_region_memory
; Code start
		AREA     startup, CODE, READONLY
				

				;ENTRY
; Reset Handler (Line 150)

Reset_Handler   PROC
                EXPORT  Reset_Handler             [WEAK]
                IMPORT  __main
                LDR     R0, =__main
                BX      R0
                ENDP
              

		END

/****************************************************************
* Author: heth@mercantec.dk
* Revision 1 - 29-aug-2011 
*****************************************************************
* Minimum setup of GPIO 
****************************************************************/
 
//related definitions from stdint.h
typedef unsigned           int uint32_t;

// GPIO related definitions in stm32f10x_cl.h
#define PERIPH_BASE           ((     uint32_t)0x40000000)
#define APB2PERIPH_BASE       (PERIPH_BASE + 0x10000)

#define GPIOA_BASE            (APB2PERIPH_BASE + 0x0800)
#define GPIOB_BASE            (APB2PERIPH_BASE + 0x0C00)
#define GPIOC_BASE            (APB2PERIPH_BASE + 0x1000)
#define GPIOD_BASE            (APB2PERIPH_BASE + 0x1400)
#define GPIOE_BASE            (APB2PERIPH_BASE + 0x1800)

#define     __IO    volatile                  /*!< defines 'read / write' permissions   */

typedef struct
{
  __IO uint32_t CRL;
  __IO uint32_t CRH;
  __IO uint32_t IDR;
  __IO uint32_t ODR;
  __IO uint32_t BSRR;
  __IO uint32_t BRR;
  __IO uint32_t LCKR;
} GPIO_TypeDef;

#define GPIOA                 ((GPIO_TypeDef   *) GPIOA_BASE   )
#define GPIOB                 ((GPIO_TypeDef   *) GPIOB_BASE   )
#define GPIOC                 ((GPIO_TypeDef   *) GPIOC_BASE   )
#define GPIOD                 ((GPIO_TypeDef   *) GPIOD_BASE   )
#define GPIOE                 ((GPIO_TypeDef   *) GPIOE_BASE   )

// RCC	 - Reset and Clock Control
#define AHBPERIPH_BASE        (PERIPH_BASE + 0x20000)
#define RCC_BASE              (AHBPERIPH_BASE  + 0x1000)
#define RCC                   ((RCC_TypeDef    *) RCC_BASE     )
typedef struct
{
  __IO uint32_t CR;
  __IO uint32_t CFGR;
  __IO uint32_t CIR;
  __IO uint32_t APB2RSTR;
  __IO uint32_t APB1RSTR;
  __IO uint32_t AHBENR;
  __IO uint32_t APB2ENR;
  __IO uint32_t APB1ENR;
  __IO uint32_t BDCR;
  __IO uint32_t CSR;
  __IO uint32_t AHBSTR;
  __IO uint32_t CFGR2;
} RCC_TypeDef;

//Main
/****************************************************************
* Author: heth@mercantec.dk
* Revision 1 - 29-aug-2011 
*****************************************************************
* Minimum setup of GPIO 
****************************************************************/
#include "minimum gpio.h"

#define FORWARD	1
#define BACKWARD 0

//Define bitmask for LED's 
/* 
   BSRR = Bit Set Reset Register

   Each port has a BSRR port which can set or reset the pin, when the port
   is configured for Output.

   Setting bit  0 to 15 will set - put a high - on the Ports corresponding pin
   Setting bit 16 to 31 will reset - put a low - on the Ports corresponding pin - 16
   
   Writing 0x100 to GPIO port E's BSRR will set Port E[0] to high (1)
   Writing 0x10000000 to GPIO port E's BSRR wilt reset Port E[0] to low (0)
*/  

//Setting BSRR bit 8 to 15 bitmasks	(lowest 16 bit set bits on)
// LED's are attached to bit 8 to 15 on the evaluation board.
const long led_on[]  = { 0x00000100, // PORT-E bit  8 ON
                         0x00000200, // PORT-E bit  9 ON
					 	 0x00000400, // PORT-E bit 10 ON
					 	 0x00000800, // PORT-E bit 11 ON
						 0x00001000, // PORT-E bit 12 ON
						 0x00002000, // PORT-E bit 13 ON
						 0x00004000, // PORT-E bit 14 ON
						 0x00008000	 // PORT-E bit 15 ON
};

//Resetting BSRR bit 8 to 15 bitmasks (highest 16 bits reset pins)
const long led_off[] = { 0x01000000, // PORT-E bit  8 OFF
						 0x02000000, // PORT-E bit  9 OFF
						 0x04000000, // PORT-E bit 10 OFF
						 0x08000000, // PORT-E bit 11 OFF
						 0x10000000, // PORT-E bit 12 OFF
						 0x20000000, // PORT-E bit 13 OFF
						 0x40000000, // PORT-E bit 14 OFF
						 0x80000000	 // PORT-E bit 15 OFF
};


int main (void) {
	int j;
	
	//led = Light Emitting Diode
	int led = 0; //Start with first LED ( 0 throug 7 as defined in led_on and led_off)
	int direction=FORWARD;

	// Start Clock on GPIO Port E (Enable port E)
	RCC->APB2ENR |=  1 <<  6;	// Bit 6 = Enable IO Port E Clock

	//Setting bit 8 to 15 of PORT E to Generel Purpose output push-pull max 50Mhz
	GPIOE->CRH=0x33333333;
	
	while (1) { 		// Do forever
		for ( j=0; j <= 100000 ; j++); //Loop for pause

		GPIOE->BSRR = led_off[led]; //Turn off Current Led
		
		//Forward Direction
		if ( direction == FORWARD ) {
			if ( led == 7 ) { // Finish in forward direction?
				direction = BACKWARD;
			} else {
				led++; // Next led forward
				GPIOE->BSRR = led_on[led];
			}
		}

		//Backward Direction
		if ( direction == BACKWARD ) {
			if ( led == 0 ) { // Finish in forward direction
				direction = FORWARD;
			} else {
				led--; // Next led backward
				GPIOE->BSRR = led_on[led];
			}
		}
	}
}