MCBSTM32C/Blinky simple
From Teknologisk videncenter
A simpe program thats blinks the eight LED's on Keil's MCBSTM32C board using the GPIO Port-E[15:8]. See Schematics
Contents
Creating a project
Assembler file: startup.s
; 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
Headerfile: minimum gpio.h
/****************************************************************
* 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;
C-File: main.c
//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];
}
}
}
}