File content as of revision 0:34ee385f4d2d:

#include "hardware_timer3.h"
#include "gpio.h"
#include "stm32f4xx_rcc_mort.h"
#include "interrupt.h"


/*Below are defined all Timers and flags required */ //Mort: These should be in a timer.c or something like that file
#define TIM3_BASE_ADDRESS ((uint32_t)0x40000400)
#define TIM3_STATUS_REGISTER (TIM3_BASE_ADDRESS + 0x10)
#define TIM3_PSC_REGISTER (TIM3_BASE_ADDRESS + 0x28)
#define TIM3_AUTORELOAD_REGISTER (TIM3_BASE_ADDRESS + 0x2C)
#define TIM3_COUNTER_REGISTER (TIM3_BASE_ADDRESS + 0x24)
#define TIM3_CAPTURE_COMPARE_MODE_2_REGISTER (TIM3_BASE_ADDRESS + 0x1C)
#define TIM_CCMR13_OC1M_0 (0b00010000)
#define TIM_CCMR13_OC1M_1 (0b00100000)
#define TIM_CCMR13_OC1M_2 (0b01000000)
#define TIM_CCMR13_OCPE (0b00001000)
#define TIM_CCMR23_
#define TIM_CCMR13_OUTPUT 0x00
#define TIM3_COMPARE3_REGISTER (TIM3_BASE_ADDRESS + 0x3C)
#define TIM3_CAPTURE_COMPARE_ENABLE_REGISTER (TIM3_BASE_ADDRESS + 0x20)
#define TIM3_CR1_REGISTER1 (TIM3_BASE_ADDRESS + 0x00)
#define TIM3_CAPTURE_COMPARE_MODE_1_REGISTER (TIM3_BASE_ADDRESS + 0x18)
#define TIM3_CAPTURE_COMPARE_REGISTER_1 (TIM3_BASE_ADDRESS + 0x34)

#define TIM3_CCMR2_CC3S_OUTPUT (0b11111100)
#define TIM3_CCMR2_OC3FE (0b11111011)
#define TIM3_CCMR2_OC3PE (0b00001000)
#define TIM3_CCMR2_OC3M1 (0b11101111)
#define TIM3_CCMR2_OC3M2 (0b01100000)

#define TIM3_INTERRUPT_ENABLE_REGISTER (TIM3_BASE_ADDRESS + 0x0C)


void TMR3CH3OutputCompare(void)
{
    uint16_t * reg;
    RCC_APB1PeriphClockCmd(RCC_APB1Periph_TIM3, ENABLE);//Enable Clock - SEE THE BUS UNDER WHICH THE REGISTER OR PERIPHERAL IS PRESENT
    
    reg = (uint16_t *)TIM3_STATUS_REGISTER; //Read flag value of STATUS REGISTER
    *reg = (~((uint16_t)0x01)); //Clear update event flag in STATUS REGISTER 
    
    reg = (uint16_t *)TIM3_PSC_REGISTER; //Read value of PRESCALER REGISTER
    *reg = 8999; //Setting the PRESCALER VALUE TO 899999, CALCULATE BY 90MHz/(Prescale + 1) --> ARR * 1/freq = 1Hz ---> freqcounter = 90MHz/(prescale +1)
    
    reg = (uint16_t *)TIM3_AUTORELOAD_REGISTER; //Read value of AUTORELOAD REGISTER
    *reg = 10000; //Count till 65535 or 2^16-1, DEFINES LIMIT UPTO WHICH COUNTER SHOULD COUNT,POST THIS IT WILL RESET ITSELF
    
    /*Setup mode resgister 2 to output compare and enable output*/ //(0b00000000 00110000)
    reg = (uint16_t *)TIM3_CAPTURE_COMPARE_MODE_2_REGISTER; //READ CAPTURE COMPARE MODE REGISTER 
    *reg = *reg | TIM_CCMR13_OC1M_1 | TIM_CCMR13_OC1M_0 | TIM_CCMR13_OUTPUT;//Setting the Output Compare to the OC3M bit fields and enabling it as an output
    
    reg = (uint16_t *)TIM3_COMPARE3_REGISTER; //READ VALUE OF COMPARE REGISTER 
    *reg = 2000; //Any value to count between two cycles- this is the value that we want to compare
    
    reg = (uint16_t *)TIM3_CAPTURE_COMPARE_ENABLE_REGISTER; //READ VALUE OF CAPTURE COMPARE ENABLE REGISTER
    *reg = *reg | 0x0100; // Enabling TIM3 Channel3 - Setting the CC3E (Enable) bit in the CCER REGISTER
    
    //Also keeping the default configuration for channel polarity
    reg = (uint16_t *)TIM3_CR1_REGISTER1;
    *reg = *reg | ((uint16_t)0x01);//Enabling the Timer3 subsystem by setting the CEN bit in TIM3_CR1 
}


void TMR3CH1GPIOCPin6asInputCapture(void)
{
    uint16_t *reg;
    RCC_APB1PeriphClockCmd(RCC_APB1Periph_TIM3, ENABLE); //Enable Clock
    
    /*Clear Status register*/
    reg = (uint16_t *)TIM3_STATUS_REGISTER; //Read flag value of STATUS REGISTER
    *reg = (~((uint16_t)0x1)); //Clear update event flag in STATUS REGISTER
    
    reg = (uint16_t *)TIM3_PSC_REGISTER; //Read value of PRESCALER REGISTER
    *reg = 9999; //Setting the PRESCALER VALUE TO 9999, CALCULATE BY 90MHz/(Prescale + 1)
    
    reg = (uint16_t *)TIM3_AUTORELOAD_REGISTER; //Read value of AUTORELOAD REGISTER
    *reg = 0xFFFF; //Count till 65535 or 2^16-1, DEFINES LIMIT UPTO WHICH COUNTER SHOULD COUNT,POST THIS IT WILL RESET ITSELF
    
    reg = (uint16_t *)TIM3_CAPTURE_COMPARE_MODE_1_REGISTER; //READ CAPTURE COMPARE MODE REGISTER 
    *reg = *reg | 0x01;//Configuring CC1 Channel as Input
    //IC1 is mapped on TI1 - Configuring the REGISTER TO INPUT CAPTURE - CC1S BIT - 01
    //ALL OTHER BITS TO BE SET FOR INPUT CAPTURE ARE 00's
    //IC1PSC - 00 - NO PRESCALER
    //IC1F - 0000 - No filter, sampling is done at fDTS - Input Capture 1 Filter 
    
    reg = (uint16_t *)TIM3_CAPTURE_COMPARE_ENABLE_REGISTER; //READ VALUE OF CAPTURE COMPARE ENABLE REGISTER
    *reg = *reg | 0x01; // Enabling TIM3 Channel1 - Setting the CC3E bit in the CCER REGISTER
    //BY DEFAULT TIMER IS SENSITIVE TO RISING EDGE - ENABLE AND KEEP IT AS IT IS 
    
    reg = (uint16_t *)TIM3_CR1_REGISTER1;
    *reg = *reg | ((uint16_t)0x01);//Enabling the Timer3 subsystem by setting the CEN bit in TIM3_CR1 
}

/* Question - Why dont we initialize or set bits of IC1PSC, IC1F AND IC1  
WHY CAN'T IT BE *reg=0b00000001*/

uint16_t readCounterValueIfFlagIsSet(void)
{
   uint16_t * reg1;
   uint16_t * reg2;
   uint16_t value;
   value=0;
   
   reg1 = (uint16_t *)TIM3_STATUS_REGISTER;
   
   if( *reg1 & (uint16_t)0b10 == 0b10 )
   {
       reg2 = (uint16_t *)TIM3_CAPTURE_COMPARE_REGISTER_1;
       value = *reg2;
       //Do we need to clear the flag? - The TIM3_STATUS_REGISTER
    }
    
    return value;
    
}
       
   //read status reguster,
   //check if CCIF1 flag is set, if it is, you clear it rc_w0
                //Statusregister = ~(CCIF1)
   //and also you read the INput caputre register and return the value. 
    

    
    
uint16_t readCounterRegister(void)
{
    uint16_t *reg;
    reg = (uint16_t *)TIM3_COUNTER_REGISTER;
    return *reg;
}

void TMR3CH3OutputPWMMode1(void)
{
    uint16_t *reg;
    RCC_APB1PeriphClockCmd(RCC_APB1Periph_TIM3, ENABLE);//Enable Clock - SEE THE BUS UNDER WHICH THE REGISTER OR PERIPHERAL IS PRESENT
    
    reg = (uint16_t *)TIM3_STATUS_REGISTER; //Read flag value of STATUS REGISTER
    *reg = (~((uint16_t)0x01)); //Clear update event flag in STATUS REGISTER 
    
    reg = (uint16_t *)TIM3_PSC_REGISTER; //Read value of PRESCALER REGISTER
    *reg = 35999; //Setting the PRESCALER VALUE TO 35999
    
    reg = (uint16_t *)TIM3_AUTORELOAD_REGISTER; //Read value of AUTORELOAD REGISTER
    *reg = 10000; //Count till 65535 or 2^16-1, DEFINES LIMIT UPTO WHICH COUNTER SHOULD COUNT,POST THIS IT WILL RESET ITSELF
    
    /*Setup mode resgister 2 to output compare and enable output*/ //(0b00000000 01101000)
    reg = (uint16_t *)TIM3_CAPTURE_COMPARE_MODE_2_REGISTER; //READ CAPTURE COMPARE MODE REGISTER 
    *reg = *reg | TIM3_CCMR2_OC3M2 & TIM3_CCMR2_OC3M1 | TIM3_CCMR2_OC3PE & TIM3_CCMR2_OC3FE & TIM3_CCMR2_CC3S_OUTPUT ;//Setting the PWM Mode 1 to the OC3M bit fields and enabling it as an output
    
    reg = (uint16_t *)TIM3_COMPARE3_REGISTER; //READ VALUE OF COMPARE REGISTER 
    *reg = 5000; //We want half of 0.5Hz - Autoreload Register is 0.5Hz and Compare Value is at 0.25Hz
    
    reg = (uint16_t *)TIM3_CAPTURE_COMPARE_ENABLE_REGISTER; //READ VALUE OF CAPTURE COMPARE ENABLE REGISTER
    *reg = *reg | 0x0100; // Enabling TIM3 Channel3 - Setting the CC3E (Enable) bit in the CCER REGISTER
    
    //Also keeping the default configuration for channel polarity
    reg = (uint16_t *)TIM3_CR1_REGISTER1;
    *reg = *reg | ((uint16_t)0x01);//Enabling the Timer3 subsystem by setting the CEN bit in TIM3_CR1 
}

void initTimer3ToInterrupt(void)
{
    uint16_t * reg;
    uint16_t prescalervalue2, autoreloadvalue;
 /* Timer 3 APB clock enable */
    RCC_APB1PeriphClockCmd(RCC_APB1Periph_TIM3, ENABLE);
 /*enable the interrupt that would go to timer 3*/
    enableNVIC_Timer3(); 
 /* Compute Prescale and Autorreload */
    prescalervalue2 = 35999; //Frequency of clock is 90 MHz
    autoreloadvalue = 10000;
 /* Clear any pending flags in the status register */
    reg = (uint16_t *)TIM3_STATUS_REGISTER;
    *reg = 0;
 /* Set Prescale and Autorreload */
    reg = (uint16_t *)TIM3_PSC_REGISTER;
    *reg = prescalervalue2;
    reg = (uint16_t *)TIM3_AUTORELOAD_REGISTER;
    *reg = autoreloadvalue;
 /* Set Compare Value */
    reg = (uint16_t *)TIM3_COMPARE3_REGISTER;
    *reg = autoreloadvalue/2; 
 /* Enable Preload Register (Don’t HAVE to, but good practice) */
    reg = (uint16_t *)TIM3_CAPTURE_COMPARE_MODE_2_REGISTER;
    *reg = *reg | 0b00001000;
 /*enable the TIM3 channel 3 counter and keep the default configuration for channel polarity*/
    reg = (uint16_t *)TIM3_CAPTURE_COMPARE_ENABLE_REGISTER;
    *reg = *reg | 0x0100;
 /*enable interrupt on capture compare channel 3*/
    reg = (uint16_t *)TIM3_INTERRUPT_ENABLE_REGISTER;
    *reg = (0x8 | 0x1); 
 /*enable timer 3*/
    reg = (uint16_t *)TIM3_CR1_REGISTER1;
    *reg = *reg | (uint16_t)0x01; 
}