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void initGPIO() { RCC->AHB1ENR |= 0x01; /* configure PA0 as ADC_IN0 */ GPIOA->MODER |= 0x03; /* analog mode */ GPIOA->OSPEEDR |= 0x03; /* high speed */ } void initADC1() { // initialize the HSI clock setbit(RCC->CR, 0); // enable HSI while (!getbit(RCC->CR, 1));// wait until HSI stable // initialize the ADC setbit(RCC->APB2ENR, 8); // enable ADC1 peripheral clock ADC->CCR = 0; // disable temperature sensor, ADC prescaler = HSI/2 clearbit(ADC1->SQR3, 0); // 1st conversion in regular sequence will be from channel0 clearbit(ADC1->SQR3, 1); // reset state - all conversions from channel0 (PA_0) clearbit(ADC1->SQR3, 2); // this is just an example clearbit(ADC1->SQR3, 3); clearbit(ADC1->SQR3, 4); #ifdef BIT12 clearbit(ADC1->CR1, 24); // 12-bit resolution (Tconv = 15 ADCCLK cycles) clearbit(ADC1->CR1, 25); // reset state #endif #ifdef BIT10 setbit(ADC1->CR1, 24); // 10-bit resolution (Tconv = 13 ADCCLK cycles) #endif #ifdef BIT8 setbit(ADC1->CR1, 25); // 8-bit resolution (Tconv = 11 ADCCLK cycles) #endif clearbit(ADC1->CR2, 11); // right alignment, reset state #ifdef LOSAMP clearbit(ADC1->SMPR2, 0); // channel0 sample rate: 3 cycles clearbit(ADC1->SMPR2, 1); // reset state clearbit(ADC1->SMPR2, 2); #endif #ifdef HISAMP setbit(ADC1->SMPR2, 0); // channel0 sample rate: 480 cycles setbit(ADC1->SMPR2, 1); setbit(ADC1->SMPR2, 2); #endif ADC1->CR2 |= ADC_CR2_ADON; // enable the ADC } void delay(int x) { volatile int i; for (i = 0; i < 1000*x; i++); } int main() { int i = 0; initGPIO(); initADC1(); while(1) { // single conversion mode, sec. 11.3.4 in RM (p. 841) setbit(ADC1->CR2, 30); // software ADC start while (!getbit(ADC1->SR, 1)); // wait until conversion end i = ADC1->DR; delay(10); } }