#include "stm32f4xx.h"
#include "LCD2x16.c"

void main (void){   

  RCC->AHB1ENR  |= 0x01 + 0x10; // Clock for PortA, E
  RCC->APB1ENR  |= 0x01;        // Clock for Timer2
  LCD_init();                   // init LCD

  GPIOA->MODER  |= 0x00000008;    // all inputs but: PA1 => AF mode
  GPIOA->AFR[0] |= 0x00000010;    // select AF1 (TIM2) for PA01 -> TIM2_CH2
  
  LCD_string("Timer2:", 0x00);          // display title string
  
  TIM2->CCMR1   |= 0x0100;        // Ch. 2 as TI2
  TIM2->SMCR    |= 0x0007;        // Ext. clk mode 1
  TIM2->SMCR    |= 0x0060;        // TI2FP2 as ext. clock
  TIM2->CR1     |= 0x0001;        // enable counting
     
  while (1) {
    LCD_uInt32(TIM2->CNT,0x40,1);       // write position to LCD
    for (int i = 0; i<100000; i++) {};     // waste some time
    if (GPIOE->IDR & 0x01)      TIM2->CNT = 0;          // reset counter
    if (GPIOE->IDR & 0x02)      TIM2->CR1 |=  0x01;     // enable counter
    if (GPIOE->IDR & 0x04)      TIM2->CR1 &= ~0x01;     // disable counter
  };
}