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Practicality Of Arduino Controlled Precision Power Feed?

Discussion in 'QUESTIONS & ANSWERS (Get Help Fast Here!)' started by shooter123456, Sep 6, 2016.

  1. JimDawson

    JimDawson Global Moderator Staff Member Director

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    That doesn't sound good. :(

    I guess it is possible but unlikely that the power supply could take out the drive. I would think it might be the other way around. I suggest that the drive may have failed, but even that is unusual.

    It sounds like the new power supply is current limiting to protect itself. Reversing the DC connections is a really bad idea, that could blow the drive if it is not reverse polarity protected.

    To start with, I might wire the motor in series rather than parallel configuration. You will lose some torque, but the load on the drive will be reduced.

    With the power off, disconnect the motor from the drive, then power up the drive and see if the power supply still current limits. If it does, the drive may have failed.
     
  2. shooter123456

    shooter123456 United States Active Member Active Member

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    Is there a way to tell if the power supply is marked correctly? Ill try wiring in series first. Though the power supply is rated for 7.3 Amps, how could the driver cause it to limit the current when drawing that much is almost double what the driver is rated for? I also can't get the driver apart to see if anything in it is blown. The power LEDs are no longer lighting either which makes me think its toast.
     
  3. JimDawson

    JimDawson Global Moderator Staff Member Director

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    You can check it with a digital voltmeter, Red lead on +, Black lead on -, the voltage should read as a positive voltage. If it is reversed, there would be a - in front of the reading. Very unlikely that the power supply is mismarked.

    If the drive has an internal short, it would draw way too much current and a good power supply will protect itself by current limiting.

    I think that is a pretty good assumption.
     
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  4. shooter123456

    shooter123456 United States Active Member Active Member

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    Thank you. Ill check all of that today. If the driver is toast, ill go ahead and order a new one. It sounds like it may be defective, but I dont know that I understand it well enough to make that call.
     
  5. Wreck™Wreck

    Wreck™Wreck United States Active User H-M Supporter-Premium

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    I have a brand new, in the box Arduino 2560 that I bought this past January. The only reason was to see how it worked and it was only $43.00 shipped.
    I simply hooked LED's to it to test the outputs and software.

    I did not like it. If you send me a shipping address I will give it to you for free including shipping if you live in the NE of the USA.

    25602_zpsxqflaxi5.jpg

    25603_zpsemxok3wd.jpg
     
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  6. jbolt

    jbolt United States Active User H-M Supporter-Premium

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    You might try and pull the cover off the drive and see if there are any blown rectifier diodes on the board, usually on the bottom of the board. They are very obvious when blown. The Chinese ones are cheap and tend to blow with voltage/current spikes. The blown diodes will cause the power supply to behave as yours is. If that is the case you will need to find out what is causing it or you had a bad drive to begin with.

    I hope you get it running. I did something similar for a power down feed for a mill I used to have. Worked great for boring large holes. I didn't do the programming though, a friend did that. Not my cup of tea so to speak.
     
  7. animal12

    animal12 United States Swarf Registered Member

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    so where did you end up with this project ?
    animal
     
  8. shooter123456

    shooter123456 United States Active Member Active Member

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    Completed it sucessfully, enjoyed it for a while, then used it to make this:
    [​IMG]

    It worked well beforehand though, highly recommended.
     
  9. shooter123456

    shooter123456 United States Active Member Active Member

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  10. cjtoombs

    cjtoombs United States Active User Active Member

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    My understanding is that the Arduino is limited to driving the stepper about 300 RPM. Don't know if you can do better than that with the Mega, it's faster than the Uno that that information was good for. You may have to modify the current code that's available for stepper driving to get the speed you want. My understanding is that the overhead of running the Arduino translator on the chip is what causes the low speed. That's not noticeable until you start doing some very time sensitive things, like bit banging a 48 kHz signal while your also trying to read inputs, count and store steps and calculate what frequency you would like to be putting out.
     
  11. shooter123456

    shooter123456 United States Active Member Active Member

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    I wrote the program myself and I didn't find that to be the case. The physical limitations of the motor and driver were the gooseneck. I remember that 1/4 stepping it and sending a pulse every 60 micro seconds to get it up a little over 1200 RPM. The motor would start stalling much higher than that.

    The program was simple, it had a while loop that would check the status of a button, if it was pressed, it sent a pulse to the driver by switching a pin from high to low, then looping back to see if the button was still pressed. I recall running a test to output the length of time for each loop, and it was in the region of 10 microseconds which means in theory, if the stepper were physically capable of it, the arduino could send it to about 7500 RPM.
     
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  12. cjtoombs

    cjtoombs United States Active User Active Member

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    That's good to know. I think both the existing libraries for stepper (stepper and acelstepper, I think) had this issue with the UNO. It's very limiting on what you can do with a stepper with an Arduino. I'm not a programmer, it kind of turned me off using it, as I didn't want the learning curve of trying to write one from scratch. It's nice that you got it to work, but I'm still not interested in writing the codes from scratch, so it's still off the table for me.
     
  13. JPigg55

    JPigg55 United States Active User H-M Supporter-Premium

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    Have you ever considered the TI Launchpad MSP430 instead of Arduino ??? http://www.ti.com/lsds/ti/tools-software/launchpads/overview/overview.page
    While I'm not a programmer, a good friend of mine is and he prefers the MSP over the Arduino as it has a better and faster processor from what he's told me. I believe Yuriy Krushelnytskiy prefers the MSP format as well.
    From my perspective, Arduino has more types of boards to choose from, seems to have a larger community, more add-ons, possibly larger library, and seems to be easier to learn. Again, this is just my opinion.
    Here's a short comparison of advantages to each I found on a website when comparing the MSP430 to the Arduino Uno.

    TI LaunchPad MSP430 Advantages:
    • Much lower cost. $10+tax and you're set. Arduno's $25+tax+shipping+buy-a-USB-cable can't compare.
    • Better built in LEDs, and a button.
    • Standard header spacing for pins, no odd 0.05" gap to foil breadboard/perfboard projects.
    • Much more flexible PWM controls. The MSP430G2553 uses a 16 bit timer for PWM rather than the Atmega328P's 8bit timer.
    • Very good low power draw features for long battery life.
    • Replacement chips don't need pre-programming/bootloading before working with the Energia IDE.

    Arduino Uno Advantages:
    • Massively huge community support. This is not to be under-estimated.
    • Stackable shields mean the sky is the limit for feature expansion.
    • Capable of 40mA source/sink per pin; this is enough for very bright LEDs. The MSP430 LaunchPad caps out at ~ 4mA.
    • Can run at 5V or 3.3V (or anywhere between 1.8V and 5V if you change oscillators). The MSP430 caps out at 3.6V.
    • More IO pins, 20 vs 16. It might not seem like a huge difference, but I have projects where I've used 18 of those pins after using a pin expander to gain 8 more.
    There are other options like Raspberry Pi which is more like a full blown computer. Here's a link to an interesting comparison of many formats.
    https://makezine.com/2014/02/07/which-board-is-right-for-me/
     
  14. cjtoombs

    cjtoombs United States Active User Active Member

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    Another huge advantage of the Arduino is that it has an open source high level language development environment. I don't know about the TI, but many of the other very capable microcontrollers out there only have publicly available assembly language development environments, the high level dev kits are available at high prices. It's also easy to learn. I think that has contributed greatly to it's popularity. If you had to use Atmel's tools and documentation to program it, it would still be almost unheard of.
     
  15. shooter123456

    shooter123456 United States Active Member Active Member

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    I did consider the MSP430 over the Arduino Mega but I went with the Arduino for a bunch of reasons.

    First is that is has 54 I/O pins and 16 analog input pins. That gave plenty of space for all of the buttons and switches I wanted as well as multiple sensors and a screen.

    Second is the ease of programming. The programmer is very easy to use, you connect your arduino to your computer with the USB, the programmer finds it and you upload your program. Easy peasy. Writing the programs also isn't hard if you have basic programming knowledge. You tell it what your variables are, what each pin is doing, and then who it should do to those variables and those pins in response to inputs.

    It also has plenty of low cost board alternatives for $10 or even less. For a beginner that has no idea what they are doing, its a lot easier to risk a $4 imported board than a $25 one.

    Everything wasn't as up front and easy with the MSP430. It wasn't super obvious what you needed to be able to program it, what the board can do, what accessories would work for it, etc. Now that I have figured out the arduino, I could probably manage the MSP430, but I stick with arduino because thats where I started and its what I know now. Though if I need more performance than the arduinos can offer, I may just end up using an MSP430.
     
  16. JPigg55

    JPigg55 United States Active User H-M Supporter-Premium

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    I wasn't putting down your choice for using Arduino. I was just posting other options available for the same or similar projects.
    All platforms have their +'s and -'s, the end user have to make an informed decision on which to use.
    Based on some of the replies here worrying about the Arduino being able to handle the task (valid or invalid), other option definitely will.
    In as far as ease of programming, the last link in my previous post talks about the newer Energia prototyping platform for MSP which (according to the article):
    "Energia lets you take your Arduino source code — your sketch — and simply drop it directly onto the MSP430".
    While I haven't used it, may be worth a check for anyone able to code for Arduino, but wanting to use the MSP430.
     

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