// using timer to trigger adc and read the cpu temperature and display the temprature to serial monitor


#include "stm32f4xx.h"                  // Device header
#include "stdio.h"
void USART2_Init(void);
void Timer2_init(void);
void ADC_Init(void);
int temp;
double voltage,degree;
int main(void)
{
USART2_Init();
Timer2_init();
ADC_Init();
printf("ADC Temperature\r\n");
while(1){
while(!(ADC1->SR)&ADC_SR_EOC){;}
temp=ADC1->DR;
voltage=(double)temp/4096*3.3;
degree=(voltage-0.76)/0.0025+25;
printf("%d,%.2f\370\r\n",temp,degree);
}
}

void USART2_Init(void){
RCC->APB1ENR|=0x20000;
RCC->AHB1ENR|=1;
GPIOA->AFR[0]=0x0700;
//GPIOA->AFR[1]=0x0700;
GPIOA->MODER|=0x0020; //set PA2 as alternate mode
USART2->BRR  = 0x008B;    //9600 @16MHz
USART2->CR1  |=0x2008; // enable tx
//USART2->CR1  |=0x2000;
}

void Timer2_init(void){
RCC->AHB1ENR|=RCC_AHB1ENR_GPIOAEN;
RCC->APB1ENR|=RCC_APB1ENR_TIM2EN;
TIM2->PSC=249;
TIM2->ARR=63999;
TIM2->CNT=0;
TIM2->CCMR1|=0x6800;
TIM2->CCER|=0x0010;
TIM2->CCR2|=50-1;
TIM2->CCR1|=1;
}
void ADC_Init(void){
//RCC->AHB1ENR|=RCC_AHB1ENR_GPIOAEN; //enable gpio a clock
RCC->APB2ENR|=RCC_APB2ENR_ADC1EN; //enable adc clock
ADC->CCR=0;
ADC->CCR=ADC_CCR_TSVREFE;
//ADC->CCR&=~ADC_CCR_VBATE;
ADC1->SMPR1|=0x1C0000;
ADC1->SQR1|=1;
ADC1->CR2=0x13000000;
ADC1->CR2|=1;
}
int USART2_write(int ch ){
while(!(USART2->SR)){;}
    USART2->DR =(ch&0xFF);
    return ch;

}
struct __FILE{int handle;};
FILE __stdout  ={1};

int fputc(int c, FILE *f){
return USART2_write(c);
}