mks base

[evilwulfie]

I tried hooking up the optical endstops http://www.ebay.com/itm/321760461548

to the Mks Base board and i am thinking that since the sensors and the
Mks base board

both have pullups the combined pullups are not allowing the signal to go
all the way low

I am getting 3.3v or so as a high and 1.3v as a low


has anybody gotten these sensors to work with a Mks base Board ?

[Anthony Webb]

Yes I have that board and those endstops. Take a look at your smoothie config I bet you are missing something small.

Sent from my iPhone

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[evilwulfie]

I dont see any way to disable the pullups
or at least no entry. maybe there was something missing in the one i got
from github
I see that there is an option to use the invert by adding ! but since
both 1.3 and 3.3v would be a high not
sure that will do anything ( i tried )

[Anthony Webb]

I will take a look at the config once I am back at the machine tomorrow to see what my config looks like.

Sent from my iPhone

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[Paul Jones]

This is what the appropriate part of my config looks like: (I'm using a similar type of optical switch)
# X Axis
alpha_min_endstop 1.24^ # add a ! to invert if endstop is NO connected to ground
alpha_max_endstop nc # NOTE set to nc if this is not installed
alpha_homing_direction home_to_min # or set to home_to_max and set alpha_max
alpha_min 0 # this gets loaded after homing when home_to_min is set
alpha_max 500 # this gets loaded after homing when home_to_max is set

# Y Axis
beta_min_endstop nc #
beta_max_endstop 1.27^ #
beta_homing_direction home_to_max #
beta_min 0 #
beta_max 315 # 24 mm from rail to stepper motor head on left

# Z Axis
gamma_min_endstop nc #
gamma_max_endstop 1.29^ #
gamma_homing_direction home_to_max #
gamma_min 0 #
gamma_max 30 #

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[evilwulfie]

looks like mine
some numbers are different but i expect that.
If you put a meter on the S ( signal ) pin of the optical endstop what
do you read when open or closed
I would expect to see one state as a low. I dont see it on mine
maybe they are defective the little LED turns on and off like its
working but the mks base dont seem to notice it

[Jason von Nieda]

I seem to remember a discussion on the FirePick list years ago about certain optical endstops not working well with 3.3v boards because of the LED. I think the solution was just to rip the LED off. Maybe that will ring a bell for someone, or maybe it would be worth searching around a bit on that topic.

Jason

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[Paul Jones]

Yes I have the same recollection. 1.3v is about right for an LED too. The end stops I’m using are actually from my FirePick and they have transistors to switch the LEDs.

Mine measure 0.1v open and 4.5v closed. That is with a SmoothieBoard

 

Paul.

 

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[evilwulfie]

I found it
https://hackaday.io/project/963-firepick-delta-the-open-source-microfactory/log/4600-6292014-present-firepick-delta-failblog-and-wins

I also removed the current limit resistor for the LED ( same thing as removing the LED but i have loads of resistors )
and it seems that it may work Its a poor design for sure

Paul do you have a link for the end stops you are using i think i would just get a few of them
I hate redesigning things for the chinese

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[Paul Jones]

I had a quick look and I didn’t see any for sale anywhere. The design docs are available here: https://github.com/firepick-delta/firepick-delta/tree/dev/electronics/eopto01

You should be able to mod yours by adding a transistor and resistor to turn on the led.

 

Paul.

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[evilwulfie]

After finding the schematic for the sensor i was able to redesign it a bit to work
I have no idea how anybody is getting them to work in the current configuration
on anything that requires a ttl low signal they way its currently designed

On 10/12/2016 10:45 PM, Paul Jones wrote:

[Anthony Webb]

FWIW, these are the ones I used, unmodified with the MKS board: http://www.ebay.com/itm/321760461548

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[Matt Baker]

I'm using the Robotdigg optical endstops.  I too found the low level output voltages to be too high, 1.3v vs 0.9v max to meet Vil specs for the microcontroller.  The bias resistor values for the output were just not meant for a 3.3v system.  I increased the resistance of either the output pull up or led bias resistor, I can't remember.  The response isn't quite as steep near the trip point as I would like so it may not be a permanent fix.  Smoothie bias settings and 5v vs 3.3v to the endstop did not help.

[Matt Baker]

Looking at the markings on a spare, I would say that they messed up the biases.  The schematic follows the standard rep rap design.  However, they biased the transmitter with 1k instead of 220 ohm, and biased the receiver with 2.2k instead of 10k.  Both changes skew the performance negatively -- weaker transmitter and larger output bias to sink in the triggered state.

[evilwulfie]

It may be that the ones you used have the correct bias resistors
they are made by so many different places all the same PCB
its no wonder that mistakes can be made

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[Matt Baker]

Mine did not have correct bias resistors, I modified them so they would work.  One piece I also re-soldered photointerrupter because it was mounted very poorly.

On Thu, Oct 13, 2016 at 5:24 PM, evilwulfie <evilw...@gmail.com> wrote:

It may be that the ones you used have the correct bias resistors
they are made by so many different places all the same PCB
its no wonder that mistakes can be made

On 10/13/2016 2:08 PM, Anthony Webb wrote:

FWIW, these are the ones I used, unmodified with the MKS board: http://www.ebay.com/itm/321760461548

On Thu, Oct 13, 2016 at 3:05 PM, evilwulfie <evilw...@gmail.com> wrote:

After finding the schematic for the sensor i was able to redesign it a bit to work
I have no idea how anybody is getting them to work in the current configuration
on anything that requires a ttl low signal they way its currently designed

On 10/12/2016 10:45 PM, Paul Jones wrote:

I had a quick look and I didn’t see any for sale anywhere. The design docs are available here: https://github.com/firepick-delta/firepick-delta/tree/dev/electronics/eopto01

You should be able to mod yours by adding a transistor and resistor to turn on the led.

 

Paul.

 

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