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Thread: Stepper driver, breakout board problems

  1. #21
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    Yep

    Need the part number printed on the chip and the pin number. We can probably find a schematic and figure out the output pin that corresponds to the input pin



  2. #22
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    Default Not working

    What about charge pump input stream of pulses?



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    They are sharp PC817 photocouplers. Very easy to find the datasheet, I am just trying to understand how they work. Here is a link to one I found. Am I right in thinking if the light is on then this thing will be on/open? so I might be able to trace it through the optocoupler if the limit switch is pressed as it does light the LEDs up on the board

    PC817 Datasheet pdf - Photocoupler - SHARP



  4. #24
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    Ref charge pump I am not sure about that, there is no mention of it in the instructions or on the board. I have used a gecko G540 before and know that had a charge pump on.

    What would I need to do?



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    Yep. An optocoupler is an LED input and a phototransistor output optically coupled. Typically, one side of the LED goes to power+ and the other side goes to the switch (which is grounded on it's other contact). Activating the switch grounds the input. There should an external current limiting resistor, usually in series from the LED to power +. The opposite photo transistor would typically have the emitter grounded, with the load connected to the collector with a resistor to power+. As you can see, if the input is pins 1 & 2, the output will be pins 15 and 16.

    You should see the input and output voltages changing from 3.something to about .5V as the input switches. Track the output pin to the parallel port connector.



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    Hi Dougie,

    It could be the opto's need a separate 5V supply to power them up.?

    My Bob needs 5v separate to the main BOB 12-50v power requirements for the opto's else the limit's wont work, It pulls the 5V thru a separate usb cable.

    The manuel shows several 5v referances on the input side so maybe needs 5v to one of these.?

    Hope this helps.



  7. #27
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    It's possible. The documentation says it uses 12-24V and doesn't mention +5. On the other hand, there are four connections for power, so who knows.

    Dougie329 could measure to see if the chips have +5. Since the outputs he is measuring are in the 3.something range, it would seem that there is +5 around.



  8. #28
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    If you look at the diagram posted 1st several days ago, on the power input I put 12v. If I measure power output it does actually give 5v from 12v in.

    Would this appear correct? I dont want to blow the board by putting 5v in where it says 5v out. There are 2 x 5v pins on marked on the back of the board. Im not sure.

    I measured the voltage on the optocoupler pins going out & got some strange results. The e-stop which is pin 10 works perfectly. I measured the voltage on the 2 opto chip output pins when the switches were unpressed and pressed.

    At rest/unpressed all 4 light up the optocoupler leds red and when pressed all 4 make the led go off which is consistent but the voltage readings are not.

    What does anyone make of this?

    Attached Thumbnails Attached Thumbnails Stepper driver, breakout board problems-wantai-019-jpg   Stepper driver, breakout board problems-wantai-023-jpg  


  9. #29
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    I'm guessing there is no pullup on the output.

    Try putting a 470 ohm resistor (value not important, 220 would probably work, 1K would probably work) from the output of the opto to +5 and try the experiment again.

    I assume that you have verified that the input is changing from 3.5 or so to zero or so when the switches are activated/deactivated = you aren't just trusting that the fact that the LED is changing state means the inputs are changing state.

    Do you know what the dip switch does?



  10. #30
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    here are the voltage measurement over the optocoupler chip input pins.

    I dont have a resistor at hand but will try and get hold of one to try that. Not sure what the dip switches are for, think they are for the relays?

    Attached Thumbnails Attached Thumbnails Stepper driver, breakout board problems-wantai-jpg  


  11. #31
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    Okay, there is definitely something wrong. Normally, the way this kind of opto coupler is used, the bottom pin is grounded, and the top pin is the output, with a pullup resistor to power. You are showing significant voltage on the emitter. It should be 0.

    I would trace the wires and see what is happening. What I am expecting is that they are all tied together (all the emitters), but some switch or wire or jumper is in the way of a ground connection. There are other ways to use the opto, so we have to see what the circuit is.

    See if you can figure out how they are wired, because there is clearly something wrong here.

    Don't bother with the resistor until we figure out why the emitter isn't grounded.



  12. #32
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    Personally I wouldn't bother and just get another board, it will be less stressful and far quicker.
    I would rather spend £50 on a new BOB and be cutting earning money than messing around chasing a dodgy board.?



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    the thing is I have 2 of these breakout boards exactly the same and they bahave in the same way so unless it is a problem duplicated when they were made I figure its something I have overlooked. + I always like to get to the bottom of these things

    Just in case can you recommend a good BOB that I can use with 1 spindle relay available in the UK?

    I will try and figure why its not grounded.



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    Hi,
    i see this is an old thread but i have the same board bought recently and con not make it work with the gecko 201x so if sb fugured how to make it work it would be nice.

    basically i have this problem and figured this:
    -no problem controlling it with Mach3 at least the leds light up and IN OUT pins work correctly
    -i power the board via 12v and it correctly outputs 5 and 12 v at the outputs
    -the board can be power also by up to 24v via the other input
    -jumper 1 is for the PWM and disables pin 16
    jumper 2 is for ??????
    jumpers 3-6 are for the relays
    -The PWM works correctly though 0-4.5v not 10V
    -my board outputs 3.75v at the STEP DIR ENABLE pins, changes correctly to Low but will not move the GECKOS, it seems that 3.7v is not enough or sth wrong with the pulses which i can not measure as i don't have an oscilloscope
    In other words everything seems ok measuring it but the geckos will not move the motors, The PWM works though 0-4.5v not 10v as stated and the relays will stick. So my guess is that it needs more power? or Sth should be enabled? or ...? In the documentation is not said that sth extra should be done
    I thought that somehow maybe it needs all the inputs to be connected and that will trigger sth, so i connected the Estop and all the home and limit switches, still nothing.

    I ordered a good board but it still bothers me that i can not make a 30euro board with PWM work, if it worked it would be the best board around for the price



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Stepper driver, breakout board problems

Stepper driver, breakout board problems