DEC home switch


Chad Gray
 

Hello, i have noticed my DEC home switch does not do the back and forth fine tuning that RA does.

RA flips the switch then waits for DEC to flip it's switch.

RA the reverses itself to find the click again and stops.  DEC never reverses.  It just stops on the first click of the switch.

Any ideas?

Chad


Howard Dutton
 

On Tue, May 17, 2022 at 08:43 AM, Chad Gray wrote:
Any ideas?
Switch bounce/electrical noise.


Chad Gray
 

Hmmm i just noticed that DEC if the telescope is pointing west it never seaks the home switch.  It just stays pointing west.

So i have run into the noise problem?  I will try a capacitor on the DEC switch.

Chad

On Tue, May 17, 2022 at 11:44 AM Howard Dutton <hjd1964@...> wrote:
On Tue, May 17, 2022 at 08:43 AM, Chad Gray wrote:
Any ideas?
Switch bounce/electrical noise.


Howard Dutton
 

On Tue, May 17, 2022 at 08:53 AM, Chad Gray wrote:
So i have run into the noise problem?  I will try a capacitor on the DEC switch.
IDK, but you wouldn't be the first if so.


Howard Dutton
 

On Tue, May 17, 2022 at 08:53 AM, Chad Gray wrote:
Hmmm i just noticed that DEC if the telescope is pointing west it never seaks the home switch.
On the other hand if the switch isn't working properly... like a missing pullup etc.

This is where having an oscilloscope becomes super handy.


Chad Gray
 

I have my 2.2k resistor on my positive wire.  Then connect DEC Home wire on the other side of that resistor.  Then connect that wire to my switch with ground on the other side of the switch.

I have a USB software/hardware oscilloscope that i use for automotive diagnostics.

If the scope is on east then it goes until switch is flipped.  

On Tue, May 17, 2022 at 12:02 PM Howard Dutton <hjd1964@...> wrote:
On Tue, May 17, 2022 at 08:53 AM, Chad Gray wrote:
Hmmm i just noticed that DEC if the telescope is pointing west it never seaks the home switch.
On the other hand if the switch isn't working properly... like a missing pullup etc.

This is where having an oscilloscope becomes super handy.


Chad Gray
 

My other MiniESP3 works great...  these electrical gremlins i dont like.  :)  I will break out the oscilloscope and see what magic smoke i can release.  :)

If there is a known good signal that i can look for let me know.  It will probably be obvious once I compare DEC home to RA.

I prefer my software gremlins

Thanks Howard!

Chad


On Tue, May 17, 2022 at 12:14 PM Chad Gray <rchadgray@...> wrote:
I have my 2.2k resistor on my positive wire.  Then connect DEC Home wire on the other side of that resistor.  Then connect that wire to my switch with ground on the other side of the switch.

I have a USB software/hardware oscilloscope that i use for automotive diagnostics.

If the scope is on east then it goes until switch is flipped.  

On Tue, May 17, 2022 at 12:02 PM Howard Dutton <hjd1964@...> wrote:
On Tue, May 17, 2022 at 08:53 AM, Chad Gray wrote:
Hmmm i just noticed that DEC if the telescope is pointing west it never seaks the home switch.
On the other hand if the switch isn't working properly... like a missing pullup etc.

This is where having an oscilloscope becomes super handy.


Chris Whitener
 

As Howard knows, I have hoisted myself in every way imaginable on the home switches.
What I have learned had me change it to the following.
1.  I use all three wires of the switch.  Gnd to NO.  Hot to NC, then Common to sense.
This allows the line to be driven up and down.  Use 2.2k resistor equivalent on sense.  Best to have something like 4.7k both on the board and on the switch  for the sense line.
2. Shorten the leads as much as possible.  this is why the dec fails before the RA.
3. Do not run the wires in the same bundle as the stepper wires.
4. Put Ferrite beads on the stepper bundle.

Look at the miniesp that works, see if you  left the pullup on the board as well as at the end of the cable.
you can add hysteresis to the sense line.  See Howards comments in the code .


Howard Dutton
 

On Tue, May 17, 2022 at 10:04 AM, Chris Whitener wrote:
See Howards comments in the code .
I think Chris is referring to OnStepX capabilities here, not sure if you're using X but there are settings to help deal with this on the software side if so.


Chad Gray
 

Yeah i am using ver 4 now.  This is the first time i have had a problem with the MiniESP3.  I just tested another one i got from George and it appears to work also.

So i think i just need to narrow down why one of my MiniESP3's does not work.  

THanks for the input!  If I figure anything out I will let you know.  Chris, maybe check out the schematic on the MiniESP3.  Maybe there is something on there that will help your OnStep computer.

Chad


On Tue, May 17, 2022 at 1:21 PM Howard Dutton <hjd1964@...> wrote:
On Tue, May 17, 2022 at 10:04 AM, Chris Whitener wrote:
See Howards comments in the code .
I think Chris is referring to OnStepX capabilities here, not sure if you're using X but there are settings to help deal with this on the software side if so.


Chris Whitener
 

Mine works fine.  
Also look how you dress the leads inside each box.  Try not to run the sense wires across the wemos for example.


Chad Gray
 

Thanks Chris.  Maybe I should develop dedicated pathways in my boxes to keep everything the same and consistent.  I am using the same wires and gauges each time.

There has to be some shielding/faraday cage like material I can add to my DEC Home Switch wires.

Chad

On Wed, May 18, 2022 at 9:42 AM Chris Whitener <chris.whitener@...> wrote:
Mine works fine.  
Also look how you dress the leads inside each box.  Try not to run the sense wires across the wemos for example.


Howard Dutton
 

On Wed, May 18, 2022 at 07:32 AM, Chad Gray wrote:
There has to be some shielding/faraday cage like material I can add to my DEC Home Switch wires.
Fiber optic all the way to the controller.


Chad Gray
 

:)  What if a black hole gets near the light in the Fiber?


On Wed, May 18, 2022 at 2:54 PM Howard Dutton <hjd1964@...> wrote:
On Wed, May 18, 2022 at 07:32 AM, Chad Gray wrote:
There has to be some shielding/faraday cage like material I can add to my DEC Home Switch wires.
Fiber optic all the way to the controller.


Chris Whitener
 

The reason that Celestron did not have issues, is the low emi generated by their cables and motors compared to Steppers.
One way would be to put the Stepper driver near the motor.  But then you have the issue of running signal wires to the driver.

Another way would be to split Howard's code, put a wemos with driver code and a driver and stepper in the axis box, then  so that the micro does the calculations and wirelessly drives the axis.


Howard Dutton
 

There are plenty of options, like the Servo42c.