#include "mbed.h"

#define DEBUG 1

float adjustment = 1.0f;

DigitalOut  led(LED1);

class Watchdog
{
public:
    /**
 * @brief
 * @note
 * @param
 * @retval
 */
    void kick(float s)
    {
        LPC_SYSCON->SYSAHBCLKCTRL = LPC_SYSCON->SYSAHBCLKCTRL | (1 << 15);  // Enable clock for watch dog 

        // When switching clock sources, both clocks must be running before the clock source is updated!
        LPC_SYSCON->WDTCLKSEL = 0x01;           // Change clock source to from IRC to 'main clock'
        LPC_SYSCON->WDTCLKUEN = 0x01;           // Update clock souce
        LPC_SYSCON->WDTCLKUEN = 0x00;           // For the update to take effect toggle WDTCLKUEN
        LPC_SYSCON->WDTCLKUEN = 0x01;           
        
        // WDT clock divider values:
        // 0: Disable WDCLK.
        // 1: Divide by 1.
        // to
        // 255: Divide by 255.
        LPC_SYSCON->WDTCLKDIV = 0x01;           // Set clock divider to 0x01 (to have fastest clocking).
        
        // Then WDCLK = main clock / clock divider. (See Fig 8. LPC111x/LPC11Cxx CGU block diagram in chapter 3.4 "Clock generation")
        uint32_t  WDCLK = SystemCoreClock / LPC_SYSCON->WDTCLKDIV;
        
#if defined(DEBUG)
        printf("WDCKL = %d\r\n, WDCLK");
#endif        
        
        // The Watchdog consists of a divide by 4 fixed pre-scaler and a 24-bit counter. The clock is
        // fed to the timer via a pre-scaler. The timer decrements when clocked. The minimum value
        // from which the counter decrements is 0xFF. Setting a value lower than 0xFF causes 0xFF
        // to be loaded in the counter. Hence the minimum Watchdog interval is (TWDCLK x 256 x 4)
        // and the maximum Watchdog interval is (TWDCLK x 2^24 x 4) in multiples of (TWDCLK x 4).

        uint32_t  TWDCLK = WDCLK / 4;
        
#if defined(DEBUG)
        printf("TWDCLK = %d\r\n, TWDCLK");
#endif        
        
        // The Watchdog should be used in the following manner:
        // 1. Set the Watchdog timer constant reload value in WDTC register.
        LPC_WDT->TC = s * (float)TWDCLK * adjust; // = time_in_seconds x number_of_ticks_per_second (min 256, max  2^24) 
        
#if defined(DEBUG)
        printf("LPC_WDT->TC = %d\r\n, LPC_WDT->TC");
#endif        

        // 2. Setup the Watchdog timer operating mode in WDMOD register.
        LPC_WDT->MOD = 0x03;    // selects Watchdog reset mode. 
        // When this mode is selected, a watchdog counter underflow will reset the microcontroller.
        // Although the Watchdog interrupt is also enabled in this case (WDEN = 1) it will not be recognized
        // since the watchdog reset will clear the WDINT flag.

        // 3. Enable the Watchdog by writing 0xAA followed by 0x55 to the WDFEED register
        //   (reloads the watchdog timer with the value contained in   LPC_WDT->TC).    
        kick();
    }

    void    kick()  {
        LPC_WDT->FEED = 0xAA; 
        LPC_WDT->FEED = 0x55;
    };
};

Watchdog  watchDog;

int main()
{
    printf("Hello World!\n");
    watchDog.kick(1);

    int hang = 0;
    
    while (1) {
        printf("loop...\n");
        wait(0.1);

        if (hang == 10) {
            while (1);
        }

        hang++;
        watchDog.kick();
    }
}