Blue Pill: Need help to identify code issue in bare metal program

[Md_ishauq]

Board name is stm32f103c8t6(blue pill) 

STM32 Bare-Metal Temperature Sensor with LED Indication

Built a bare-metal application on STM32 to read the inbuilt temperature sensor via ADC by directly configuring registers (no HAL). The ADC value is mapped to an LED blink rate, where the LED speed changes according to the sensed temperature, showcasing low-level peripheral programming and real-time feedback.

The issue is the led is constantly blinking! 

I have given the code plz help me solve it

#include<stdint.h>
#include<stdio.h>

//registers used
volatile uint32_t *RCC_APB2ENR =(volatile uint32_t *)0x40021018;
volatile uint32_t *GPIOx_CRH =(volatile uint32_t *)0x40011004;
volatile uint32_t *GPIOx_ODR =(volatile uint32_t *)0x4001100C;
volatile uint32_t *ADC_SQR3 =(volatile uint32_t *)0x40012434;
volatile uint32_t *ADC_SMPR1 =(volatile uint32_t *)0x4001240C;
volatile uint32_t *ADC_CR2 =(volatile uint32_t *)0x40012408;
volatile uint32_t *ADC_SR =(volatile uint32_t *)0x40012400;
volatile uint32_t *ADC_DR =(volatile uint32_t *)0x4001244C;



void internal_tempsensorInit(){
	*RCC_APB2ENR |= (1<<4);//PORTC clock enabled
	*RCC_APB2ENR |= (1<<9);//ADC1 clock enabled


	//port c pin 13 configuration
	*GPIOx_CRH &= ~(0xF << 20); // Clear bits
	*GPIOx_CRH |= (0x2 << 20); // 0b0010 = Output, 2MHz, push-pull

	*ADC_SQR3 &=~(0x1F<<0);//clear SQ1
	*ADC_SQR3 |=(16<<0);//select channel 16

	*ADC_SMPR1 &=~(0x7<<18);//clear sample time for channel 16
	*ADC_SMPR1 |=(0x7<<18);//set sample time (239.5cycles)

	*ADC_CR2 |=(1<<23);//set temperature sensor
	for (volatile uint32_t i = 0; i < 10000; i++); // ~short delay
	*ADC_CR2 |=(1<<0);//set ADON ADC ON

	//CALIBRATION
	*ADC_CR2 |=(1<<3);//RESET calibration
	while(*ADC_CR2&(1<<3)){//wait until its cleared

	}
	*ADC_CR2 |=(1<<2);//SET calibration
	while(*ADC_CR2&(1<<2)){//wait until its cleared

	}

	//continuous conversion
	*ADC_CR2 |=(1<<1);
}

uint16_t adcread(){


	*ADC_CR2 |=(1<<22);//start of conversion

	while(!(*ADC_SR&(1<<1))){
			}
	return (uint16_t) *ADC_DR;
}

static inline void delay_ms(uint32_t ms) {
 // crude ~ms delay assuming ~72MHz, adjust if too fast/slow
 for (uint32_t m=0; m<ms; m++) {
 for (volatile uint32_t i=0; i<72000; i++) {
 __asm__("nop");
 }
 }
}

void tempdelay(){
 for(uint32_t i=1;i<=80000;i++);
}


int main(){

	internal_tempsensorInit();
	(void)adcread(); // throw away first reading
	while (1) {
 	 uint16_t analog_value = adcread();

 	 float Vsense = (analog_value * 3.3f) / 4095.0f;
 	 float temperature = ((1.43f - Vsense) / 0.0043f) + 25.0f;

 	 uint32_t ms = (uint32_t)(temperature * 50.0f); // ~1.5s around 30°C
 	 if (ms < 100) ms = 100; // clamp for visibility
 	 if (ms > 2000) ms = 2000;

 	 *GPIOx_ODR &=~ (1<<13);// LED ON (active-low)
 	 //tempdelay();
 	 delay_ms(1000);
 	 *GPIOx_ODR |= (1<<13); // LED OFF
 	 //tempdelay();
 	 delay_ms(1000);
 	}


}

[TDK]

> The issue is the led is constantly blinking!

Isn't that what your code does? What are you expecting?

 

I echo the replies you got on your last post. Use the standard headers. Debug the code and see what values you're getting for the delay vs what you expect.

HELP ME indentify the problem in the code that wri... - STMicroelectronics Community

[Andrew Neil]

As @TDK says, your code still seems much the same as in your previous thread.

Did you get that working?

• If so, please mark the solution in that thread.
• If not, you should concentrate on getting that working before going on to something else!

[kposyniak]

Instead of:

 	 delay_ms(1000);
 	 *GPIOx_ODR |= (1<<13); // LED OFF
 	 //tempdelay();
 	 delay_ms(1000);

 

try:

 	 delay_ms(ms);
 	 *GPIOx_ODR |= (1<<13); // LED OFF
 	 //tempdelay();
 	 delay_ms(ms);

 

[Andrew Neil]

Also, rather than a read-modify-write (RMW) on ODR, look at BSRR and BRR:

https://www.st.com/resource/en/reference_manual/rm0008-stm32f101xx-stm32f102xx-stm32f103xx-stm32f105xx-and-stm32f107xx-advanced-armbased-32bit-mcus-stmicroelectronics.pdf#page=173

via: https://www.st.com/en/microcontrollers-microprocessors/stm32f103c8.html#documentation