/* p7_1.c: A to D conversion of channel 1

 * This program converts the analog input from channel 1.
 * Channel 1 is connected to input from PA1.
 * Clock prescaler is left at 0 (divided by 2) and Sampling
 * time is also left at default of 3 cycles.
 * Software trigger is used. The bit 8 of the conversion
 * result is used to turn on/off the LD2. For the full
 * scale of the reference voltage, the LD2 should be on
 * for 8 times.
 *
 * This program was tested with Keil uVision v5.23 with DFP v2.0.0.
 */

#include "stm32f0xx.h"

int main(void)
{
	int result;

	/* set up pin PA5 for LED */
	RCC->AHBENR |=  0x00020000;             /* enable GPIOA clock */
	GPIOA->MODER &= ~0x00000C00;            /* clear pin mode */
	GPIOA->MODER |=  0x00000400;            /* set pin to output mode */

	/* set up pin PA1 for analog input */
	GPIOA->MODER |=  0xC;       			/* PA1 analog */

	/* setup ADC1 */
	RCC->APB2ENR |= 0x00000200;             /* enable ADC1 clock */
	ADC1->CR = 0;                           /* SW trigger */
	ADC1->CFGR1 = 0;
	ADC1->CFGR2 = 0;
	ADC1->CHSELR = 1 << 1;
	ADC1->CR |= 1;                 			/* enable ADC1 */

	while (1) {
		ADC1->CR |= 0x00000004;             /* start a conversion */
		while (!(ADC1->ISR & 0x00000002)) {
		}                                       /* wait for conv complete */
		result = ADC1->DR;                      /* read conversion result */
		if (result & 0x100)
			GPIOA->BSRR = 0x00000020;       /* turn on LED */
		else
			GPIOA->BSRR = 0x00200000;       /* turn off LED */
	}
}