Hard Disk Motor Controlling

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rajudp

Joined: 27 May 2006
Posts: 238
Helped: 10
Location: India

31 Jan 2007 11:54 hard disk motor

Please anybody give information about hard disk motors. it is having 3 pins and showing same resistance between them

with regards

raju

RollingEEE

Joined: 25 Mar 2006
Posts: 208
Helped: 4
Location: Bangladesh

31 Jan 2007 13:28 harddisk motor

Hey, I have one of them too.
I just tried to apply 9V between 2 terminals while keeping the 3rd terminal open. The motor rotated few degrees. By choosing seperate pairs of wire serially and applyingvoltage across them you can rotate the motor. Alternatively, you can use a microcontroller, and an optocoupler to drive the motor.

rajudp

Joined: 27 May 2006
Posts: 238
Helped: 10
Location: India

02 Feb 2007 20:04 hard disc motor

yes you are right . but how to control it. and how the pins are used for proper operation
thanks and regards
raju

kender

Joined: 19 Jun 2005
Posts: 1231
Helped: 88
Location: Stanford, SF Bay Peninsula, California, Earth, Solar System, Milky Way

02 Feb 2007 21:11 change hard disk motor

I'm almost certain that your disk has a brushless DC (BLDC) motor. Since it has only 3 leads, I think, it's a sensorless BLDC. I've never worked with such motors, but if you google "BLDC" or "sensorless BLDC", you'll get a tonn of app notes with schematics, algorithms and code.

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E-design

Joined: 01 Jun 2002
Posts: 947
Helped: 68

03 Feb 2007 1:22 how to use a harddisk motor

I think if you generate a 3 phase switching supply it should run. Never tried it myself.

RollingEEE

Joined: 25 Mar 2006
Posts: 208
Helped: 4
Location: Bangladesh

03 Feb 2007 7:48 how to run a 3 wire hard disk motor

I used this code for my AT89S52 microcontroller. Please remember to use an optocoupler to isolate the microcontroller pins from any direct electric contact with the motors, and also use a current amplifier to avoid toasting your optocoupler.

#include "reg52x2.h"

/*

* FUNCTION_PURPOSE: This file set up timer 0 in mode 2

* with a software gate.

duty = (256-RL_OFF)/[512-(RL_ON+RL_OFF)]

*/

#define fCrystal 20000 /* in kilohertz */
#define fPWM 1 /* rotation speed in RPS */
#define Instr_Per_Cycle 12
#define Duty 100 /*percent*/

#define RL_ON_C (256 - Duty * fCrystal / fPWM / Instr_Per_Cycle)
#define RL_OFF_C (512 - RL_ON_C - fCrystal / fPWM / Instr_Per_Cycle)

unsigned char RL_ON = RL_ON_C, RL_OFF = RL_OFF_C;

bit flag = 0;
unsigned char stat = 1;

unsigned int count = 0;

void main(void)

{

TMOD &= 0xF0; /* Timer 0 mode 0 with software gate */

TMOD |= 0x02; /* GATE0=0; C/T0#=0; M10=1; M00=0; */

TH0 = RL_ON; /* init values */

TL0 = RL_ON;

ET0=1; /* enable timer0 interrupt */

EA=1; /* enable interrupts */

TR0=1; /* timer0 run */

P2_0 = 0; /* Initialize P2.0 */

while(1); /* endless */

}

void it_timer0(void) interrupt 1 /* interrupt address is 0x000b */

{

TF0 = 0; /* reset interrupt flag*/

if (flag == 1)

{
TH0 = RL_OFF;
if (stat == 0)
{
P2_0 = 1;
P2_1 = 0;
P2_2 = 0;
stat = 1;
}
else if (stat == 1)
{
P2_0 = 0;
P2_1 = 1;
P2_2 = 0;
stat = 2;

}

else if (stat == 2)
{
P2_0 = 0;
P2_1 = 0;
P2_2 = 1;
stat = 0;

}
}

if (flag == 0)

{

TH0 = RL_ON;

}

count++;

if (count == 1000)

{

if (P1_0 == 0) RL_ON++;

if (RL_ON >240) RL_ON = 240; // Upper limit

if (P1_1 == 0) RL_ON--;

if (RL_ON < 16) RL_ON = 16; // Lower Limit

RL_OFF = 512 - RL_ON;

count = 0;

}

flag = ~flag;

}

Added after 7 minutes:

I forgot to mention:

Pin P2.0 P2.1 P2.2 should be connected to motor's 3 wires. If your motor does not rotate, try different combinations of motor wires and pins

Added after 8 minutes:

And in case you forgot, there is a 'helped me' button to press if you have found this information helpful.