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MastaMoose
Joined: 07 May 2009
Posts: 3
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| Help with Servo Motors: Control of Servo Motor |
 Posted: Sat May 09, 2009 5:06 pm |
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hi, i am new to both this forum and PIC programing in general. I am using:
-CCS PCM compiler
-2 PIC 16F877
-MPLAB 8.30
So my problem is that i want to control a servo motor, "remotely." What this means is that i want to have two PICs (as mentioned above) that will correspond serially.
Also, the first of said PICs is connected to a potentiometer and will serially transmit the digital data to the second PIC. The second PIC is charged with converting the digitally recieved data to produce a pulse train that will drive a servo motor.
The problem is that my code is sending, and recieving everything okay, but the servo motor does not move. I am sure of the specification however, meaning i am sure that the last code snippet that generates the pulse works on its own when interfaced with a pot through a single chip, but does not work when one chip is input and the other is output.
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Masta Moose
Last edited by MastaMoose on Sat May 09, 2009 5:08 pm; edited 1 time in total |
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MastaMoose
Joined: 07 May 2009
Posts: 3
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| Continued with code |
| Posted: Sat May 09, 2009 5:07 pm |
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Here is my code:
Thus I wish to implement potentiometer controller servo motor. The code is as follows:
SENDER CODE:
| Code: |
//Takes pot input and converts it and then sends it out serially
//****************************************************
//****************************************************
#include <16F877.h>
#fuses XT, NOWDT, NOPROTECT, BROWNOUT, PUT, NOLVP
#use delay(clock = 20000000)
#define ADC = 8
#use rs232 (baud=9600, xmit=pin_c6,rcv=pin_c7, parity=N)
//This is the main function
/*****************************************************/
/*****************************************************/
void main ()
{
//This is the code to setup the ADC stuff
int A2D_Value = 0;
SET_TRIS_B ( 0x00 );
setup_adc_ports ( RA0_ANALOG );
setup_adc ( ADC_CLOCK_INTERNAL );
set_adc_channel ( 0 );
DELAY_MS(10);
//now we are going to send the A2D value of the input serially
while(1)
{
A2D_Value = read_adc(ADC_START_AND_READ);
putc(A2D_Value);
}
} |
RECEIVER CODE:
| Code: |
//This code takes the serially transmitted Digtal value and generates a //pulse to control a servo motor
/**********************************************************/
/*********************************************************/
#include <16F877.h>
#fuses XT, NOWDT, NOPROTECT, BROWNOUT, PUT, NOLVP
#use delay(clock = 20000000)
#define ADC = 8
#use rs232 (baud=9600, xmit=pin_c6,rcv=pin_c7, parity=N)
char timed_getc()
{ //this i changed from char to int
long timeout;
timeout=0;
while(!kbhit()&&(++timeout<50000)) // 1/2
delay_us(10);
if(kbhit())
{
return(getc());
}
else
{
return(0);
}
}
void main()
{
char value;
float value2;
long x;
{
while (TRUE)
{
while(!kbhit());
set_tris_D (0X00);
value=timed_getc();
value2=value;
x = 1250 + (500*value2/256);
OUTPUT_D (0b11111111);
DELAY_US(x);
OUTPUT_D (0b00000000);
DELAY_US(20000-x);
}
}
} |
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Masta Moose |
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bungee-
Joined: 27 Jun 2007
Posts: 206
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| Posted: Sat May 09, 2009 5:20 pm |
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Try to put some delay between two transmissions.
And did you try to send fixed values to other pic and did the servo react?
I posted a multi servo code here on forum. You could adapt this code to your needs. The way you are doing it is putting PIC on delay all the time  |
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MastaMoose
Joined: 07 May 2009
Posts: 3
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| Posted: Sun May 10, 2009 10:32 am |
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okay i tried puting a delay of 20 milliseconds after the sending code and the servo started reacting but i only got a quarter of the range. I will have to check it more on monday when i get back to the lab. So i will update this on monday. Thank you for your help.
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Masta Moose |
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