AVR-Chat

Dear all

       Have someone can share example about PWM or step motor 
controller . thanks

       Luke

For a atmega 128 gcc

void initmotor(void)
{
/* use fast PWM mode 10 bit with toggle on compare
Reference pages 130 table 58 
Page 133 table 61 

	f OCn = f clk_I_O
	    	-------------
		     N *  (1 + TOP) 
 f clk_I_O = 16000000

Top can be either 
 ff ( 255)  for mode 5 
1ff ( 511)  for mode 6
3ff (1023) for mode 7
       prescales
Mode	1 		8		64		256
1024
5	   62500  7812.5   976.5   244.1    61
6	   31250  3906.2   488	    122     30
7	   15625  1953     244      61      15

use mode 6 with 8 prescale
*/

// need to set TCCR3A register


// page 130 
// TCCR3B register needs to look like bit 7 - 4 = 0 bit 3 = 1 bit 2 = 0
bits 1 =0 and bit 0 = 1
//ICNC3 ICES3 - WGM33 WGM32 CS32 CS31 CS30 
// 0	0	  0	0		1	0	 0
1

// TCCR3A 
//bit 7 	6 		5 		4 	3
2 	1 		0
//COM3A1 COM3A0 COM3B1 COM3B0 COM3C1 COM3C0 WGM31 WGM30 
//1			0		1	0		0
0	1		1

// turn everything off
LeftEnable = 0;
RightEnable = 0;

TCCR3A = BV(WGM31);  /* set timer/counter 3 to fast PWM mode 6 */
TCCR3A |= BV(COM3A1) | BV(COM3B1); /* Clear OCnA/OCnB/OCnC on compare
match when up-counting. */
TCCR3B = BV(CS31) | BV(WGM32) ; /* prescale: 8 @ 16 MHz, 10 bit PWM
overflows @ 1953 HZ */ 

// turn everything off
OCR3A= 0;
OCR3B= 0;

DDRE |= BV(PORTE3)|BV(PORTE4); /* enable PWM outputs */

// set these as output (pins 0 through 3 on port A)
DDRA |= BV(PORTA0) | BV(PORTA1) | BV(PORTA2) | BV(PORTA3) ;



}


To to forward I set the pins for direction and then this code sets the
speed to close to 100%

OCR3A = 500;
OCR3B = 500;

-- turns the motor off
OCR3A = 500;
OCR3B = 500;



There are other aspects about pwm control of motor that depend on the
hbridge

-----Original Message-----
From: Luke.Wei [mailto:mrddt4todie@yahoo.com.tw] 
Sent: Thursday, February 17, 2005 10:32 PM
To: AVR-Chat@yahoogroups.com
Subject: [AVR-Chat] Have someone can share example ?




Dear all

       Have someone can share example about PWM or step motor 
controller . thanks

       Luke





 
Yahoo! Groups Links