SainSmart End Stops and stepper problems

I have recently assembled a prusa i3 rework and connected it to Megatronics V2.0. I have wired a 24V power supply properly and have no connection issues with my megatronics to my computer. I have installed Arduino software and uploaded Marlin. I have now two issues that I have spent hours on and that I suspect are programming related:

1. my sain smart end stops disconnect power to my board when I plug them in when the switch is NOT activated. I suspect that the switches are wired NO, and the logic needs to be inverted. I have done a lot of googling and searching this on the web and everything points to changing the configuration.h file. No matter what changes I make to the 'Y_MIN_ENDSTOP_INVERTING = true' etc lines the switch does the same thing. How do I properly invert the logic on the end switches? Does it have something to do with the "pullups" (which I have no clue is)?

2. My stepper motors currently receive no signal. they have the 6 wires, and I have identified the poles with a multimeter and connected the wires in order to the megatronics board. I have tried both configurations (1,2,3,4 and 4,3,2,1). I have received signals in the past with the megatronics test program in arduino, but now no signal and I don't have a clue if it is program related or mechanical. Does someone have more information on how exactly to connect the 4 wires to the megatronics, and what settings I can play with for them to receive power again?

Thanks for any help. All I ask for is at least a point in the right direction on these issues, I am stuck and frustrated. Thanks for your time.

Bill C.

For problem #1, there was a long thread here a few months ago regarding endstop wiring. Read it TO THE END, as there was some mistaken information posted that could not be deleted. If the Megatronics board loses power when you trip an endstop switch, it is mis-wired and shorting out. Don't test it again until you fix it, or you will blow the board!!!!!

Did you follow this? [reprap.org]

You are probably sending 5v into signal or ground...

For number 2, I tried to find what pins are what but there is no documentation saying anything other than "X Motor here" which seems to line up with whoever decided to add stupid comments in Marlin like "Invert this value for Mendel, leave True for Orca" on the motor direction...but moving on.

I will assume you are using A4988, you can take a multimeter on continuity test and find which pins correspond to the ones on the stepper drivers. You can find the stepper driver pinout here [www.pololu.com] which should help you out with the motor wiring.

Thank you guys for the help, I really appreciate it.

vreihen - do you have the link to the topic? or maybe the keywords? i cant seem to find what disucssion you refer to.

tjb1 - I have looked at that, but dismissed it because i have the sainsmart mechanical end stops, which have 4 wires. This has been the most confusing part, connecting the correct 4 leads of the end stops to the 3 pins (or less) to the megatronics. Do I only need to use 2 of the 4 leads from the SainSmart end stops after all?

-Bill C.

The website covers which pins are what - [www.sainsmart.com]

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BillC

vreihen - do you have the link to the topic? or maybe the keywords? i cant seem to find what disucssion you refer to.

http://forums.reprap.org/read.php?219,160740,160740#msg-160740

Read through TO THE END before making any hookups, as there were mistakes made along the way!

If you decide to use all three wires and not just the two-wire method, the LED on the endstop board should turn on whenever the switch is pressed. I got away with a few very quick taps of the endstop switch when it was mis-wired without damaging my board, but I don't recommend that you test your luck given the other reported failures in that thread.....

Thanks Vreihen! that thread was useful. I found the correct wiring method for my endstops, and my board is in one piece. Thank you for the help.

tjb1, thanks for the info on the endstops and stepstick

I have looked at the wiring of my step stick (a4988) and compared it to the published outputs of my stepper motors. I have corrected them and I still have no signal to the motors. When I test the output pins on the Megatronics board while running the MegatronicsV2test I get no voltage. There must be an issue with my board.

I notice that there are 4 sets of pins underneath where the step stick goes. Do these need to be jumpered? will this effect the output for the motors? What else am I missing that would hinder a voltage output to my stepper motor outputs?

-Bill C

Edited 2 time(s). Last edit at 05/03/2014 12:35PM by BillC.

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BillC
I notice that there are 4 sets of pins underneath where the step stick goes. Do these need to be jumpered?

They are the micro-stepping jumpers, and yes, three out of four sets of pins need to be jumpered for each stepper. SainSmart doesn't ship the required jumpers with their boards for some reason, so you'll have to source them locally. In the States, Radio Shack has them in packs of 10 for $1.49 in most stores:

http://www.radioshack.com/product/index.jsp?productId=2103807

If you haven't seen it yet, the Megatronics 2.0 Datasheet has pictures of the board with jumpers installed:

http://reprapworld.com/mt/datasheet%20megatronicsv2.pdf

It also shows the proper silk-screening for pin labels, many of which (such as the endstop polarity) SainSmart omitted from their boards.....

Another thing to check for the steppers not moving is that your 12V supply is on. The electronics can draw 5V from the USB port and appear to be working, but the steppers and heaters need the external 12V rail(s) to be powered.....

I have a question if u don't miend do u need to do any thing to the configurations h fiel in marlin or just put the pins in and go