Can anyone help me figure out what I'm doing wrong? (trying to use ADC on STM32F3 discovery board)

[jugal]

I wrote this code to initialize ADC1. What Im trying to do is take input from a Joystick and map it accordingly and send a corresponding PWM output to a LED.

        RCC->CFGR |= RCC_CFGR2_ADCPRE12_DIV2;
        RCC->AHBENR |= RCC_AHBENR_ADC12EN;       //enable clock 
	ADC1->CR &= ~(ADC_CR_ADVREGEN_1 | ADC_CR_ADVREGEN_0); 
	ADC1->CR |= ADC_CR_ADVREGEN_0; //voltage regulator enable sequence
	ADC1->CR &= ~ADC_CR_ADCALDIF;
	ADC1->CR |= ADC_CR_ADCAL;	        //start calibration							
	while((ADC1->CR)& ADC_CR_ADCAL);	//wait till calibrated
	ADC1->CR |= ADC_CR_ADEN;
	while(!( (ADC1->ISR) & ADC_ISR_ADRDY ));
	ADC1->SQR1 |= ADC_SQR1_SQ1_1 | ADC_SQR1_SQ1_0; 	   //channel 3 in sequence 1				
	ADC1->SMPR1 |= ADC_SMPR1_SMP3_2 | ADC_SMPR1_SMP3_1; //sampling rate for ch3 		 
	ADC1->CFGR  |= ADC_CFGR_CONT;     	//set to continuous conversion mode
	ADC1->CR |= ADC_CR_ADSTART;

The program is stuck in one of the while loops (I'm guessing due to some problem with ADC calibration? idk). I know this because the rest of my code never executes, if it did, I would be able to see an output on the LED. It would be a great help if someone can help me figure out what I'm doing wrong here.

[MWeid.2]

Can you do something like light up a LED after the first white loop? Then you know if the first or second while loop is the problem.

[jugal]

Okay i just did it. The first loop is the problem, the calibration is not successful.

[waclawek.jan]

> RCC->CFGR |= RCC_CFGR2_ADCPRE12_DIV2;

You meant

RCC->CFGR2 |= RCC_CFGR2_ADCPRE12_DIV2;

JW

[jugal]

Okay I fixed that line, but the main problem persists.

[waclawek.jan]

Still looping in calibration, or is it something else?

Read it and check all registered content, including RCC.

PLL is set how?

Try clocking ADC from AHB.

JW

[jugal]

okay I'll try these. I haven't messed with PLL or any other clock settings, everything is at default settings. Yes, it is still stuck in calibration.

[jugal · Accepted solution]

Problem solved thanks! i just set the CKMODE bits. From the ref manual:

01: HCLK/1 (Synchronous clock mode). This configuration must be enabled only if the AHB

clock prescaler is set to 1 (HPRE[3:0] = 0xxx in RCC_CFGR register) and if the system clock

has a 50% duty cycle.