Re: [DIYbio] Building semicontinuous minicentrifuge with HD motor.

Dear Nathan,

Thanks for your attention.

Markos

On 22-08-2014 15:56, Nathan McCorkle wrote:
> First off, the digitalwrites in that code are sequential, and I'm
> almost certain it would be better if they were happening
> simultaneously. If this is so, then this will certainly reduce the
> maximum speed.
>
> Check out this to get simultaneous pin switching/setting:
> http://www.arduino.cc/en/Reference/PortManipulation
>
> It probably isn't required for your purposes, but microstepping can
> increase the smoothness of the rotation, though it is probably more
> important in low-speed applications, but if you have the time to do
> microstepping it won't hurt to do so (i.e. instead of step-transitions
> between high and low, there is a curve of power applied, which can be
> emulated using PWM (which because of the inductance on the motor
> windings should actually smooth out the PWM spikes)):
> http://arduino.cc/en/Tutorial/SecretsOfArduinoPWM
>
> I have some arduino code that sets up the sine lookup-table (sine wave
> is pretty smooth, so that's what they use), and anytime there's a
> transition on the coils, instead of just turning one off and another
> on instantaneously, it performs the transitions using PWM (starting at
> 0% duty, e.g. full-off, progressing up to 100% duty, e.g. full-on). I
> can post this code later tonight.
>
>
>
> On Fri, Aug 22, 2014 at 11:12 AM, Markos<markos@c2o.pro.br> wrote:
>
>> Dear Nathan,
>>
>> I am using a motor with 4-wire and the resistance measurements were:
>> http://www.c2o.pro.br/en/automation/download/wiring_HD_motor.png
>>
>> To control I assembled the circuit:
>> http://www.c2o.pro.br/en/automation/download/BLDC_controller_4_wires_MOSFET.jpg
>>
>> And I'm using the code (Arduino):
>> http://bartvenneker.nl/schemas/Code_arduino_hdd.txt
>>
>> That I found at:
>> https://www.youtube.com/watch?v=CMz2DYpos8w
>>
>> Using a encoder from a mouse and a oscilloscope I measured a speed of 3500
>> rpm.
>>
>> I have yet to fix two plates of acrylic (plexiglass) which will increase the
>> weight and I'll probably lose speed.
>>
>> If I reduce minStepLength less than 1200 than the motor stops turning.
>>
>> How can I optimize this code to increase the speed?
>>
>> Thanks for the attention,
>> Markos
>>
>>
>> On 21-08-2014 04:05, Nathan McCorkle wrote:
>>
>>> I've done some microstepper code using the hardware timers of an
>>> arduino, and I know a friend that did some BLDC code on a similar
>>> processor using back EMF.
>>>
>>> On Wed, Aug 20, 2014 at 8:01 AM, Markos<markos@c2o.pro.br> wrote:
>>>
>>>
>>>> Hi,
>>>>
>>>> I'm working on building a circuit (with MOSFET) and a software (with
>>>> Arduino) to control HD motors to be used in a DIY "semicontinuous"
>>>> minicentrifuge.
>>>>
>>>> Has anyone worked with these motor? (spindle motor, bldc motor, used in
>>>> Hard
>>>> Disks)
>>>>
>>>> I would like to exchange information with someone with experience in
>>>> controlling these motors.
>>>>
>>>> Thanks,
>>>> Markos
>>>>
>>>>
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>>>
>>>
>>>
>>>
>>
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>
>
>

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