Need help !!! I want to make 3 delay functions which works guaranteed delay in nanoSecond, microSecond and milliSeconds using Timer.

[Vivek yadav1]

What i am currently using to achieve my goal.

Few Details :

1: STM32F103C8 Blue Pill

2: CMISS core Library

3:Datasheet, Reference Manual and Programming Manual

I have attached two files. Which give you some idea that how I want to make These 3 functions. I want to understand at Register level.

I want to configure Registers by myself.

Thanks & Regards

@Vivek yadav​ 

[dbgarasiya]

you have to add TIM1->EGR , which is for update count

and then get value in

TIMx->CNT ,which will increment as per millisecons

[dbgarasiya]

.

[Vivek yadav1]

I am Trying to generate 1 sec time delay. So i write a code. In which as per my calculation. LED must Toggle at every 1 sec.

Can Any one guide me Where am i wrong ?

 
// This header file contains memory mapping of all peripherial
#include "stm32f10x.h"
 
 
void toggleLED()
{
	GPIOC->ODR ^= GPIO_ODR_ODR13;
}
 
int main()
{
FLASH->ACR |=  FLASH_ACR_LATENCY_0;
// by default HSI is selected which is 8 Mhz
RCC->CR |= RCC_CR_HSION;
while(!RCC_CR_HSIRDY);
// HSI divide by 8 i.e frequancy = 8 Mhz/8 = 1 Mhz
RCC->CFGR |= RCC_CFGR_SW_HSI | RCC_CFGR_HPRE_DIV8 | RCC_CFGR_MCO_HSI;
// Port C and Timer 1 is selected
RCC->APB2ENR |= RCC_APB2ENR_IOPCEN | RCC_APB2ENR_TIM1EN;
/*	GPIO Block	*/
// Pin13,10 Mhz, Analog 	
GPIOC->CRH |= GPIO_CRH_MODE13_0 ;
							
	
	
/*		Timer Block	*/	
TIM1->CR1 |=  TIM_CR1_ARPE	|
							TIM_CR1_CMS_0 |
							TIM_CR1_DIR		|
							TIM_CR1_CEN ;
	
TIM1->EGR |= TIM_EGR_UG; 
TIM1->PSC = 0;// count at every 1 pules
TIM1->ARR = 1000 - 1;
//	Tout = (ARR+1)*(PSC+1)/Fclk
// Tout = 1000*1/1 Mhz
// Tout = 1/1000 sec == 1 milli Sec
uint16_t cnt =0;
 
// After configuraing Timer i am expected to toggle the LED at every 1 sec.
while(1)
{
	if(TIM1->CNT == 999)
		cnt++;
 
	if(cnt == 1000)
	{
		cnt =0;
		toggleLED();
	}
 
}	
 
}

[Vivek yadav1]

I am getting 3 sec delay

[dbgarasiya]

Try this code

RCC->APB2ENR |= (1<<0);  // Enable clock set as per your controller datasheet

TIM1->PSC = 54000; // My timer clock is 54 Mhz : 54 MHZ/ 54000 == 1 ms cnt

TIM1->EGR = TIM_EGR_UG;

TIM1->CR1 = TIM_CR1_CEN;

you will get ms delay .. i have not used TIM1->ARR , here

[Vivek yadav1]

didn't work for me

[dbgarasiya]

what is the issue coming ?

is that showing differnt value . or counter does not starts at all ?

[Vivek yadav1]

#include "stm32f10x.h"
 
#define BIT(x) (1<<x)
void init()
{
	RCC->CR   |= RCC_CR_HSION;//enable HSI 8 MHz RC Oscillator
	RCC->CFGR |= RCC_CFGR_PLLSRC_HSI_Div2; // 8/2 = 4 MHz
	RCC->CFGR |= RCC_CFGR_PLLMULL9; // 4*9 = 36 Mhz
	RCC->CFGR |= RCC_CFGR_SW_PLL; // PLL selected as system clock
	while(!RCC_CFGR_SWS_PLL); // Wait for PLL to be ready
	
	RCC->APB2ENR |= (1<<0);  // Enable clock set as per your controller datasheet
	RCC->APB2ENR |=  RCC_APB2ENR_IOPCEN;//Port C enable
	RCC->APB2ENR |= RCC_APB2ENR_TIM1EN;//Timer1 Enable
	TIM1->PSC = 36000; // My timer clock is 36 Mhz : 36 MHZ/ 36000 == 1 ms cnt
 
	TIM1->EGR = TIM_EGR_UG;
 
	TIM1->CR1 = TIM_CR1_CEN;
 
}
 
void configurePins()
{
    // Turn on GPIO C 
    RCC->APB2ENR |= BIT(4);
    // Configure PC13 as an output
    GPIOC->CRH |= BIT(20);
    GPIOC->CRH &= ~(BIT(23) | BIT(22) | BIT(21) );
}
 
int main()
{
	init();
	configurePins();
		
	TIM1->ARR = 1001;
	uint16_t cnt =0;
 
	while(1)
	{
 
		if(TIM1->CNT == 1000 )
		{
			cnt++;		
		}
		else if(cnt == 1000)
		{
			GPIOC->ODR ^= BIT(13);
			cnt = 0;
		}
	}//End-while
 
	
}

*

I wrote this code.

[Piranha]

Milliseconds - if you're beginner, look at what others have done before you. Implement a software system tick counter and make delay function wait on that. https://www.keil.com/pack/doc/CMSIS/Core/html/group__SysTick__gr.html

Microseconds - a sane code rarely needs such a delays. Forget it for now.

Nanoseconds - there doesn't exist such a thing as a precise nanosecond delays based on software. Only hardware can do it and implementation will always be specific to particular use. Therefore forget it at all.

[S.Ma]

Very precise output timings seems now possible with STM32 having HiResolutionTimer. The learning curve might be steep as it's equivalent to a 4GHz timer.