Hello again everybody.
I have run into the following problem: I try calibrate the ADC1 and plain calibration seems to work just fine (apparently), but as soon as I try to follow the Extended Calibration procedure, described on page 1007 of the Holy User Guide, then the ADCAL bit never clears. Could please someone point out what is the problem? Here is a snippet of my clumsy code:
void ADC_init(void){
PWR->SVMCR |= (PWR_SVMCR_ASV); //Removing Analog supply (VDDA) isolation, necessary in order to power ADC1 LDO up
//**Internal reference buffer init
RCC->APB3ENR |= (RCC_APB3ENR_VREFEN); //Power the reference buffer
__NOP();
__NOP();
RCC->SRDAMR |= (RCC_SRDAMR_VREFAMEN); //Enable reference buffer during sleep mode
//!!!__!!! Unsolder SB3 bridge on the board
VREFBUF->CSR = 0; //Reference out pin is now connected to the reference buffer and the buffer is disabled
VREFBUF->CSR |= (3 << VREFBUF_CSR_VRS_Pos); //2.5V reference selected
VREFBUF->CSR |= VREFBUF_CSR_ENVR; //Reference buffer enabled
while(!(VREFBUF->CSR & VREFBUF_CSR_VRR)){} //Waiting for the reference voltage to stabilize
//**Powering up ADC1
ADC12_COMMON->CCR |= (ADC_CCR_PRESC_3); //ADC1 clock/8 (ADC1 clock must be less than 55MHZ)
RCC->AHB2ENR1 |= (RCC_AHB2ENR1_ADC12EN); //Enable ADC1
ADC1->CR &= ~(ADC_CR_DEEPPWD); //Exit ADC1 power down mode
ADC1->CR |= ADC_CR_ADVREGEN; //Enable ADC1 LDO
while(!(ADC1->ISR & ADC_ISR_LDORDY)){} //Wait for the LDO to get ready
//**Extended calibration
ADC1->CR |= ADC_CR_ADCALLIN; //Set the linear calibration bit
ADC1->CALFACT &= ~(ADC_CALFACT_CAPTURE_COEF +
ADC_CALFACT_LATCH_COEF);
ADC1->CR |= ADC_CR_ADEN; //Enabling ADC1
while(!(ADC1->ISR & ADC_ISR_ADRDY)){} //Waiting for the ADC1 to get ready
ADC1->CR |= (0b1001 << ADC_CR_CALINDEX0_Pos);
ADC1->CALFACT2 = 0x00020000;
ADC1->CALFACT |= ADC_CALFACT_LATCH_COEF;
ADC1->CALFACT &= ~(ADC_CALFACT_LATCH_COEF);
ADC1->CR |= ADC_CR_ADCAL; //Starting extended calibration
while(ADC1->CR & ADC_CR_ADCAL){} //GOT STUCK HERE
while(ADC1->CR & ADC_CR_ADEN){} //Making sure all is done
//**
}
The Extended calibration procedure starts at line 19. Thank you!
