adc showing garbeg value

You're going to have to get a lot better at presenting your problems if you expect others to diagnose them.

The code and sample data would describe a lot of the issues you are failing to convey.

What rate are you sampling at now, have you quantified that?
Do the samples hit the rails? What is the swing of the square wave?
Does it have a DC offset?

You're going to have to get a lot better at presenting your problems if you expect others to diagnose them.

The code and sample data would describe a lot of the issues you are failing to convey.

What rate are you sampling at now, have you quantified that?
Do the samples hit the rails? What is the swing of the square wave?
Does it have a DC offset?

thanks, i am setting adc at 9mhz, and no of cycles 55.5, while giving signal through function generator i am giving .5v around offset. problem:

here the while loop is working only once ,but if i am removing 'systick' intrrupt then it is working continuously.
what is the better option to store(update) particular size of array regularly in real time implimentation ??
since i am taking 512 amount so the perticular sine wave is not coming ,what i suppose to do with it?

void main()
{ RCC->APB2ENR |= ( 1UL << 4); GPIOC->CRL &= ~0x000F0000;
#ifndef __ADC_IRQ RCC->AHBENR |= ( 1UL << 0); DMA1_Channel1->CMAR = (uint32_t)&ADC_last; DMA1_Channel1->CPAR = (uint32_t)&(ADC1->DR); DMA1_Channel1->CNDTR = 1; DMA1_Channel1->CCR = 0x00002522; NVIC_EnableIRQ(DMA1_Channel1_IRQn); DMA1_Channel1->CCR |= (1 << 0);
#endif RCC->CFGR |= ( 3UL << 14); RCC->APB2ENR |= ( 1UL << 9); ADC1->SQR1 = 0; ADC1->SQR2 = 0; ADC1->SQR3 = (14UL << 0); ADC1->SMPR1 = ( 5UL << 12); ADC1->CR1 = ( 1UL << 8); ADC1->CR2 = ( 7UL << 17)| ( 1UL << 20) ;
#ifndef __ADC_IRQ ADC1->CR2 |= ( 1UL << 8);
#else ADC1->CR1 |= ( 1UL << 5); NVIC_EnableIRQ(ADC1_2_IRQn);
#endif ADC1->CR2 |= ( 1UL << 0); ADC1->CR2 |= 1 << 3; while (ADC1->CR2 & (1 << 3)); ADC1->CR2 |= 1 << 2; while (ADC1->CR2 & (1 << 2));
while(1)
{ i=0;
while(i<512)
{ ADC1->CR2 |= (1UL << 22);
SysTick_Config(SystemCoreClock / 100);
ADC_last = ADC1->DR;
voltage1[i] = (double)(3.00 * ADC_last)/4096.0;
i++; ADC1->SR &= ~(1 << 1);
} ADC1->CR2 &= ~(1UL << 22);
}

Please read the posting notes and use PRE tags when posting code.

I can barely decipher this. There is a whole mess of DMA, IRQ, and then you read the ADC1->DR with no attention to if the conversion is complete. Pick ONE method and apply it consistently.

You need to get this out of your loop, it has no purpose being there
SysTick_Config(SystemCoreClock / 100);