I had bought RC Micro Servo Motor (HD-1160A) from cytron. I had tried loaded the coding that given into PIC 16F877and it was successful.The servo motor turn 180 degree in anti clockwise. So, i tried modified the PIC programming that given in order to turn the RC Micro servo motor to 90 degree and it will turn back to 0 degree in 50times.But, the RC Micro Servo motor only turn 90 degere and not turned back to 0 degree in 50 times.I not really good in PIC microcontroller programming. Below is the program that I had modified. I need a help to check which part should I modified in order to turn the RC Micro servo motor to 90 degree and it will turn back to 0 degree in 50times. Thanks in advance
- CODE: SELECT_ALL_CODE
#include <pic.h> // this sample code is using 16F877A !!
// configuration
//==========================================================================
__CONFIG ( 0x3F32 ); //configuration for the microcontroller
// define
//==========================================================================
#define servo RB1
#define MHZ *1000L /* number of kHz in a MHz */
#define KHZ *1 /* number of kHz in a kHz */
// Value x must not more that 255
#define DelayUs(x) { unsigned char _dcnt; \
_dcnt = (((x)*(20MHZ))/(24MHZ))|1; \
while(--_dcnt != 0) \
continue; \
_dcnt = (((x)* (20MHZ))/(24MHZ))|1; \
while(--_dcnt != 0) \
continue; }
// function (every function must have a function prototype)
//==========================================================================
void DelayMs(unsigned char y); // Value y must not more that 255
// delay ms
// main function (main fucntion of the program)
//==========================================================================
void main(void)
{
unsigned int i,a;
//set IO port for servo pin
TRISB = 0b00000001; //servo motor is RB1
PORTB = 0b00000000; //clear port B
//servo will loop infinity
while(1) //from one position to another position
{
//*******************************************************
//
//Delay determine the servo motors position
//Try change the value for different position
//
//Value in DelayUs and DelayMs function must not more than 255
//Otherwise the timing will not accurate!!
//
//******************************************************
for(i=0;i<50;i++) //continues pulse for 50 times
{
servo=1; //set servo pin high
DelayUs(150);
DelayUs(150);
DelayUs(100); //delay 250+250+200= 700us = 0.7ms
//These delay only valid using 20MHz!
servo=0; //set servo pin low
DelayMs(19.2); //remain --> 20ms-0.7ms=19.3ms
DelayUs(50);
DelayUs(20); //19ms+0.250ms+0.050ms=19.3ms
//These delay only valid using 20MHz!
}
// _ _ _
// | | | | | |
// | | | | | | ~~50 times
// | |_________________| |________________| |____________________
// 0.7ms 19ms 0.7ms 19ms 0.7ms 19ms
// | |
// |<-------20ms------>|
// for(i=0;i<50;i++) //continues pulse for 50 times
//{
// servo=1; //set servo pin high
//DelayMs(2); //delay 2ms
//These delay only valid using 20MHz!
//servo=0; //set servo pin low
// DelayMs(18); //delay 18ms
//These delay only valid using 20MHz!
// }
// ___ ___ ___
// | | | | | |
// | | | | | | ~~50 times
// | |_______________| |_______________| |____________________
// 2ms 18ms 2ms 18ms 2ms 18ms
// | |
// |<-------20ms------>|
}
}
//subroutine
//============================================================================
void DelayMs(unsigned char y)
{
unsigned char i;
do {
i = 4;
do {
DelayUs(250);
} while(--i);
} while(--y);
}
