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--- en:examples:motors:servo [2009/03/26 16:06] – raivo.sell
+++ en:examples:motors:servo [2010/02/04 12:30] (current) – removed mikk.leini
@@ Line 1: / Line 1: @@
-====== RC Servo ======
-Servo motors are often used in radio-controlled (RC) models, and are very useful in
-many kinds of small robotics applications because they are compact and inexpensive.
-An RC servo motor includes a built-in DC motor, gearbox, position feedback sensor
-(usually potentiometer), and drive electronics. RC servo motors can be controlled by
-an external pulse-width modulation (PWM) signal. If a signal meets RC servo timing
-requirements, it usually “describes” a (target) position input for the servo drive
-electronics. Servo motor electronics compare the shaft position with the inputted
-position, trying to find a shaft position where they match. The position control signal
-is a continuous square-wave signal, as depicted in figure.
-Servo motors have three wires:
-  * Red = Power supply Vcc (4.8–6V)
-  * Black = Ground
-  * White/yellow = PWM input (may vary type-by-type)
-The PWM signal has the following shape:
-{{:examples:actuator:pwm_signal.jpg|?400}}
-.0ms = farthest left position
-.5 ms = center position
-.0 ms = farthest right position
-===== Electrical connection =====
-{{:examples:actuator:servo_schema.jpg?250|}}
-Table of motor drive signals from ATmega128 to the actuator board.
-{{:examples:actuator:servo_connection_table.jpg|}}
-Electrical connections
-  - Make sure all power is off.
-  - Connect the actuator board and main board with a 26-pin cable.
-  - Connect the RC servo motor to the actuator board, as shown in Figure 2.
-Note: The signal wire (usually yellow or white) is towards the outer
-edge of the board.
-  - Connect the JTAG converter with the ATmega128 main board and the PC.
-  - Finally connect the power to the main and actuator boards.
-{{:examples:actuator:servo.jpg?500|}}
-===== Example code =====
-<code c>
-/*-------------------------------------------------------------
-Title:		RC Servo motor with Actuator Board
-Date:		080327
-Ver.:		1.1
-Compiler:	AVR-GCC
-Target:		ATmega128
-Hardware:	ATmega128 controller board, Actuator board, RC servo motor
-Author: 	Raivo Sell 2008
-Notes:	Description: Moves slowly RC motor shaft from one edge to another.
----------------------------------------------------------------*/
-#define F_CPU 14745600UL //CPU Frequency (influences delay function)
-#include <avr/io.h>
-#include <util/delay.h>
-///////////////// Main function //////////////////////////////////
-int main (void){
-	// Set timer control registers
-	TCCR1A = _BV(COM1A1) | _BV(COM1B1) | _BV(WGM11);
-	TCCR1B = _BV(CS11) | _BV(WGM13) | _BV(WGM12);
-    	DDRB 	 = 0x30;  // PB5 & PB6 output
-	ICR1   = 36000; // Sets the upper limit to Timer1
-    			//(creates 50 Hz signal) XTAL/8/256*50   14745600
-	OCR1A  = 2700;  // Sets when the PWM signal should toggle.
-	while(1){
-		for(OCR1A=500;OCR1A!=5000;OCR1A++)  {_delay_ms(3);}
-		for(OCR1A=5000;OCR1A!=500;OCR1A--)  {_delay_ms(3);}
-	}
-}
-</code>

en/examples/motors/servo.1238083591.txt.gz · Last modified: 2020/07/20 09:00 (external edit)