[PIC] Need help urgent, Having a hard time with timers and compare modules

[edwinvarghese]

I'm trying to modify the below code for my project it is written in MIkro C by late Mr.Warren Schroeder. I'm having a hard time understanding what happening inside interrupt routines :sad::-|. Someone please help with the following code.
Thanks in advance......

/* 
 //'******************************************************************************* 
 //'  Program to Control 12- 50Hz Servos @ 16 Positions Each With USART Updates 
 //'******************************************************************************* 
 //'           Code compiled with mikroC 8.2 and tested on 16F887 @ 8MHz 
 //'           By Warren Schroeder  June 5, 2008 
 //'******************************************************************************* 
 //'******************************************************************************* 
 //' 
 //'           Each USART RX Byte: 
 //'              Servo ID        = Upper 4 bits  (0 to 11)   12 Servos 
 //'              Servo Position  = Lower 4 bits  (0 to 15)   16 Positions 
 //' 
 //'   HITECH-HS422 50Hz Servo: 940us to 2140us for min and max servo rotation 
 //'                            16 positions (940us= Position#0 + (15 x 80us)) 
 //'                            Position#7 = 1500us Center 
 //' 
 //'       Timer1 Setup for 1us ticks  (Prescaler=2) 
 //' 
 //'       CCP1 is set up for Special Event Compare Mode 
 //'       On Compare-Match between TIMER1 and CCPR1L:CCPR1H registers 
 //'       CCP1IF is Set (=1) and TIMER1 is RESET (=0) 
 //' 
 //' 
 //'******************************************************************************* 
 //'******************************************************************************* 
 */ 
 
 #define Servo0  PORTB.f0 
 #define Servo1  PORTB.f1 
 #define Servo2  PORTB.f2 
 #define Servo3  PortB.f3 
 #define Servo4  PORTB.f4 
 #define Servo5  PORTB.f5 
 #define Servo6  PORTB.f6 
 #define Servo7  PORTB.f7 
 #define Servo8  PORTD.f0 
 #define Servo9  PORTD.f1 
 #define Servo10 PORTD.f2 
 #define Servo11 PORTD.f3 
 
 unsigned int register volatile 
    CCPR1          absolute 0x0015               ; 
 unsigned short AllOn                       ; 
 unsigned short frame80                     ; 
 unsigned short t0                          ; 
 unsigned short t1                          ; 
 unsigned short t2                          ; 
 unsigned short ServoPos[12]                ;  //  12 Servo Position Array from RX 
 unsigned short ServoWrk[12]                ;  //  12 Servo Position Work Array 
 
 
 void interrupt() { 
     if (AllOn) {                              //  If AllOn flag=true then 
            PORTB = 255                     ;  //  All PORTB servos ON 
            PORTD = 15                      ;  //  All PORTD servos ON 
            AllOn = ~AllOn                  ;  //  reset AllOn flag 
            frame80 = 0                     ;  //  80us frame counter 
            CCPR1 = 940                     ;  //  940us = 0 position 
            for (t2=0;t2<12;t2++) {            //  load work array from USART RX array 
               ServoWrk[t2] = ServoPos[t2  ];  // 
            } 
     }                                         // 
     else {                                    // 
            CCPR1 = 80                      ;  //  80us frame delay (x 15 total = 1200us) 
            FSR = (unsigned short)&ServoWrk ;  //  servo pointer.. point to first servo pos 
            if (INDF == 0) Servo0  = 0      ;  //  turn servo OFF on 0 
            INDF--                          ;  //  decrement position counter 
            FSR++                           ;  //  point to next servo 
            if (INDF == 0) Servo1  = 0      ;  //  turn servo OFF on 0 
            INDF--                          ;  //  decrement position counter 
            FSR++                           ;  //  point to next servo 
            if (INDF == 0) Servo2  = 0      ;  //  turn servo OFF on 0 
            INDF--                          ;  //  decrement position counter 
            FSR++                           ;  //  point to next servo 
            if (INDF == 0) Servo3  = 0      ;  //  turn servo OFF on 0 
            INDF--                          ;  //  decrement position counter 
            FSR++                           ;  //  point to next servo 
            if (INDF == 0) Servo4  = 0      ;  //  turn servo OFF on 0 
            INDF--                          ;  //  decrement position counter 
            FSR++                           ;  //  point to next servo 
            if (INDF == 0) Servo5  = 0      ;  //  turn servo OFF on 0 
            INDF--                          ;  //  decrement position counter 
            FSR++                           ;  //  point to next servo 
            if (INDF == 0) Servo6  = 0      ;  //  turn servo OFF on 0 
            INDF--                          ;  //  decrement position counter 
            FSR++                           ;  //  point to next servo 
            if (INDF == 0) Servo7  = 0      ;  //  turn servo OFF on 0 
            INDF--                          ;  //  decrement position counter 
            FSR++                           ;  //  point to next servo 
            if (INDF == 0) Servo8  = 0      ;  //  turn servo OFF on 0 
            INDF--                          ;  //  decrement position counter 
            FSR++                           ;  //  point to next servo 
            if (INDF == 0) Servo9  = 0      ;  //  turn servo OFF on 0 
            INDF--                          ;  //  decrement position counter 
            FSR++                           ;  //  point to next servo 
            if (INDF == 0) Servo10  = 0     ;  //  turn servo OFF on 0 
            INDF--                          ;  //  decrement position counter 
            FSR++                           ;  //  point to next servo 
            if (INDF == 0) Servo11  = 0     ;  //  turn servo OFF on 0 
            INDF--                          ;  //  decrement position counter 
 
            if (++frame80 == 16) {             //  finished 15 80us position periods? 
                CCPR1 = 18800               ;  //  load remaining time for 20ms interrupt 
                AllOn = ~AllOn              ;  //  turn ON all servos at next 20ms interrupt 
            } 
     } 
     PIR1.CCP1IF = 0                        ;  //  clear CCP1 interrupt flag 
 } 
 
 
 void CCP1_Setup() { 
     CCP1CON      = 11         ;  //  CCP1 Compare MODE with special event trigger; resets Timer1 on match 
     CCPR1        = 65000      ;  //  preload for 65ms delay before servo startup 
     T1CON        = 16         ;  //  Timer1 Prescaler = 2 = 1us ticks 
     PIE1.CCP1IE  = 1          ;  //  Enable CCP1 interrupt 
     PIR1.CCP1IF  = 0          ;  //  Clear CCP1 Interrupt Flag 
     INTCON       = 192        ;  //  Global & Peripheral interrupts enabled 
     T1CON.TMR1ON = 1          ;  //  Start Timer1... 
 } 
 
 
 
 void main() { 
 
     ANSEL   = 0               ;   //  disable adc's 
     ANSELH  = 0               ;   //  disable adc's 
     CM1CON0 = 0               ;   //  disable comparators 
     CM2CON0 = 0               ;   //  disable comparators 
     PORTB   = 0               ; 
     PORTD   = 0               ; 
     TRISB   = 0               ; 
     TRISD   = 0               ; 
     AllOn   = 255             ;   //  all servos ON flag 
     
 
     USART_INIT(19200)                 ; 
     CCP1_Setup()                      ; 
     
     
          for (t0=0;t0<12;t0++) {         //  pre-load servo array with some values 
              ServoPos[t0] = t0        ;  // 
           } 
           
           
     while(1) { 
        if (USART_DATA_READY) {           // test for RX byte 
           t0 = USART_READ()            ; // save new RX byte 
           t1 = t0 >> 4                 ; // extract servo ID from RX byte 
           ServoPos[t1] =  t0 & 15      ; // save Position Value per ID 
         } 
     } 
 
 }

please help me with this, Thanks in advance ......

 

[ravi1488]

Dear friend,
it is very well explained with comments.
Where is the problem?

 

[edwinvarghese]

@ Ravi,
First of all thank you friend . I understood the code:-D
I was new to timers and interrupts that was problem, Now i understood the working of Timers and Interrupts
anyway thank you for your helping mentality............