By the way, I am so sorry about my english if I couldn't explain properly what I am doing .I am making a project that controls brusless dc motor with stm32f407 development board.
First, I controlled brushless dc motor with arduino and observed pwm output pin on the oscilloscope screen. I recognized that brushless dc motor doesn't work by giving %100 power. I understand that I need to make soft start by widening duty cycle. Arduino sends a pwm signal that has 50 Hz frequency(20ms period) and duty cycle in between minimum %10, maximum %12.5. I wrote a code on stm that controls brushless dc motor by using pwm on GPIOD12 pin. I set timer7 configurations as generate an interrupts every 1us and increment a counter in TIM7_IRQHandler() function. When counter reaches 6410 number,it is resetted. I defined Duty variable that has 100 value and incremented by 1 every 1 us till it reaches 240 value.I n infinite while loop, when counter is smaller 3*Duty variable, GPIOD12 pin is set. In between 3*duty variable and 6410 value, GPIO12 pin is in reset. When duty variable increases, pulse width is increases .I am trying to make a soft start with using this way. But I can't control dc motor with using this way. Can you tell me what am I doing wrong?
#include "stm32f4xx.h"
void Timer7pwmGeneratorInit(void); //Timer7pwmGeneratorInit prototype
void SystemInitt(void); //SystemInitt prototype
int Duty = 100; //Duty variable that represents duty cycle.
int i; //Counter variable
long counter=0; //counter variable
int main() {
Timer7pwmGeneratorInit(); //Timer7pwmGeneratorInit is called in main/ SystemInitt(); //SystemInitt is called in main
while(1) {
if(counter < ( 3 * Duty)){
GPIOD->ODR |= (0x1000); } //When counter is smaller than 3*Dutyvariable,set GPIOD12 pin.
else if( counter > ( 3 * Duty) && counter < 6410)
{ GPIOD->ODR &= ~(0x1000); //When counter is in between 3*Duty and 6410 value,counter is resetted. }
}
}
void Timer7pwmGeneratorInit(void){
RCC->APB1ENR|=0x00000020; // Timer7 clock is activated(84 Mhz)
TIM7->CR1=0x0080; // Automatic Reload
/*********Timer 7 frequency --> fCK_PSC / (Loaded Value + 1) 84E6 / (42) = 2000 KHz**************/
TIM7->PSC =41; // Prescaler value is 41, Counting frequency = fCK_PSC / (Loaded Value + 1) 84E6 / (42) = 2000 KHz
TIM7->ARR =1; // When counter is equals to 1,returns. Timer interrupt is generated every 1 uS
TIM7->DIER=0x0001; // Update Int enable
NVIC->ISER[1] = 0X00800000; // NVIC de Timer 7 interrupta is enabled
TIM7->CR1 |= 0x0001; // Counter Enabled
}
void TIM7_IRQHandler(){
TIM7->SR=0; //Timer 7 status register is resetted
counter++; //counter is incremented by 1
if(counter>=6410) //When counter is equals to 6410,counter is resetted.
counter=0;
if(Duty < 240) { duty is smaller than 240, increase duty by 1.
Duty = Duty + 1; //increase duty by 1.}
}
void SystemInitt(void){
unsigned int i;
for (i=0;i<0x00100000;i++);
RCC->CFGR |= 0x00009400; // AHB ve APB speeds are setted max value
RCC->CR |= 0x00010000; // HSE Xtal osc start to work
while (!(RCC->CR & 0x00020000));// Xtal osc get stabilized
RCC->PLLCFGR = 0x07402A04; // PLL coefficients M = 4, N = 168, P = 2 and Q = 7 168 Mhz
RCC->CR |= 0x01000000; // PLL starts (Rehber Sayfa 95)
while(!(RCC->CR & 0x02000000)); // Wait until PLL is ready
FLASH->ACR = 0x00000605; // 5 Wait state was selected for Flash ROM and ART is activated. (Rehber Sayfa 55)
RCC->CFGR |= 0x00000002; // System Clk feed through PLL
while ((RCC->CFGR & 0x0000000F) != 0x0000000A); // Wait till feeds
RCC->AHB1ENR |= (1UL << 3); // Clock Signal Active for Port D
GPIOD->MODER |= 0x01000000; // output pin for LED D12
GPIOD->OSPEEDR |= (2UL << 0); // GPIO Port Output Speed(High)
GPIOD->PUPDR &= ~(3UL << 0); // No Pull-Up Pull-Down for PD0
}
