CGEM Progress #celestron #fysetc


Brian Davis
 

So, I'm closing in on my CGEM build, largely done following Francois Buechard and Chris Vaghn's build details.  I recently picked up a FYSTEC S6/TMC2130s, and left the MKS GEN-L board for another project.  My build also includes a Raspberry Pi 4b4g, which runs INDI (Stellarmate), and has an attached ADAFruit GPS with it's PPS output driving a pin on the PI tied to /dev/pps0.  The PI is running a fully configured NTP server, and rates as a Stratum 1 timeserver - meaning it is a serious reference time source.  (I actually compared it's accuracy to a Spectracom rubidium timeserver I had left from a commercial radio system - and the Pi is not much less accurate!).

Which begs the question - how can I best use the accuracy of the time source  to regulate time on the FYSETC?  I can tie to a pin on the Pi I think by linking a GPIO pin to the /dev/pps0 output, and use INDI to set time on Onstep (on the FYSETC)?   I'd like to use the Pi's PPS output, which has the benefit of making the entire system run on the same (very) exact time.  Would I need to add an RTC to the FYSETC?

Second question related to micro-stepping -  suggestions for best combination of tracking/slewing micro-steps?  I have it running now with 32/8 (slews are very fast).  Any reason not to try 64/8 or even 128/8?  Theoretical accuracy gain, but does that translate to a measurable improvement in actual performance?

A few pics follow - I'll send a completed build set, and final 3d print files to the list when complete. 



Khalid Baheyeldin
 

On Tue, Jun 1, 2021 at 08:09 PM, Brian Davis wrote:
how can I best use the accuracy of the time source  to regulate time on the FYSETC?  I can tie to a pin on the Pi I think by linking a GPIO pin to the /dev/pps0 output, and use INDI to set time on Onstep (on the FYSETC)?   I'd like to use the Pi's PPS output, which has the benefit of making the entire system run on the same (very) exact time.  Would I need to add an RTC to the FYSETC?
OnStep cannot get the PPS signal in any way other than a pin.
So if you can provide that to OnStep, from the Pi, you are done.

I also use KStars/Ekos/INDI myself.
The way I set things up is that I have the GPS (AGM336H module) on OnStep.
Then in KStars preferences unde INDI, I say : Mount updates Time/Location on KStars.
Works well except for an annoying thing that KStars things it is one hour behind (probably due to DST), but pointing is still in sync with OnStep.

Second question related to micro-stepping -  suggestions for best combination of tracking/slewing micro-steps?  I have it running now with 32/8 (slews are very fast).  Any reason not to try 64/8 or even 128/8?  Theoretical accuracy gain, but does that translate to a measurable improvement in actual performance?
Usually no practical difference observed.
But try out 32 vs. 128 and let us know if you notice any ...


Chad Gray
 

Hi Brian, i do not have an answer for you, but i do have a RaspberryPi/GPS question.  :)

I also have the Adafruit GPS plugged in via the GPIO pins.  I have it setup to have PPS be the time source. I followed this guide.

My problem is if i plug in a USB device (ZWO camera, Celestron Nextstar, ZWO focuser, QHY guide scope) to the Raspberry Pi i lose my GPS!  It has to do with the serial port, but i do not know what to start doing to debug it and find a fix to always have the GPS on /dev/ttys0

If you want to take this off the list you can email me direct.

Thanks!
Chad

On Tue, Jun 1, 2021 at 8:09 PM Brian Davis <tapperbld@...> wrote:
So, I'm closing in on my CGEM build, largely done following Francois Buechard and Chris Vaghn's build details.  I recently picked up a FYSTEC S6/TMC2130s, and left the MKS GEN-L board for another project.  My build also includes a Raspberry Pi 4b4g, which runs INDI (Stellarmate), and has an attached ADAFruit GPS with it's PPS output driving a pin on the PI tied to /dev/pps0.  The PI is running a fully configured NTP server, and rates as a Stratum 1 timeserver - meaning it is a serious reference time source.  (I actually compared it's accuracy to a Spectracom rubidium timeserver I had left from a commercial radio system - and the Pi is not much less accurate!).

Which begs the question - how can I best use the accuracy of the time source  to regulate time on the FYSETC?  I can tie to a pin on the Pi I think by linking a GPIO pin to the /dev/pps0 output, and use INDI to set time on Onstep (on the FYSETC)?   I'd like to use the Pi's PPS output, which has the benefit of making the entire system run on the same (very) exact time.  Would I need to add an RTC to the FYSETC?

Second question related to micro-stepping -  suggestions for best combination of tracking/slewing micro-steps?  I have it running now with 32/8 (slews are very fast).  Any reason not to try 64/8 or even 128/8?  Theoretical accuracy gain, but does that translate to a measurable improvement in actual performance?

A few pics follow - I'll send a completed build set, and final 3d print files to the list when complete. 



Brian Davis
 

Chad,

Offhand, it sounds like you have everything tied to the same serial port (something like /dev/ttyAMA0 ).  You may need to map serial TTYs to each device to prevent conflict?

Just a first guess...

Brian

On Tue, Jun 1, 2021 at 7:46 PM Chad Gray <rchadgray@...> wrote:
Hi Brian, i do not have an answer for you, but i do have a RaspberryPi/GPS question.  :)

I also have the Adafruit GPS plugged in via the GPIO pins.  I have it setup to have PPS be the time source. I followed this guide.

My problem is if i plug in a USB device (ZWO camera, Celestron Nextstar, ZWO focuser, QHY guide scope) to the Raspberry Pi i lose my GPS!  It has to do with the serial port, but i do not know what to start doing to debug it and find a fix to always have the GPS on /dev/ttys0

If you want to take this off the list you can email me direct.

Thanks!
Chad

On Tue, Jun 1, 2021 at 8:09 PM Brian Davis <tapperbld@...> wrote:
So, I'm closing in on my CGEM build, largely done following Francois Buechard and Chris Vaghn's build details.  I recently picked up a FYSTEC S6/TMC2130s, and left the MKS GEN-L board for another project.  My build also includes a Raspberry Pi 4b4g, which runs INDI (Stellarmate), and has an attached ADAFruit GPS with it's PPS output driving a pin on the PI tied to /dev/pps0.  The PI is running a fully configured NTP server, and rates as a Stratum 1 timeserver - meaning it is a serious reference time source.  (I actually compared it's accuracy to a Spectracom rubidium timeserver I had left from a commercial radio system - and the Pi is not much less accurate!).

Which begs the question - how can I best use the accuracy of the time source  to regulate time on the FYSETC?  I can tie to a pin on the Pi I think by linking a GPIO pin to the /dev/pps0 output, and use INDI to set time on Onstep (on the FYSETC)?   I'd like to use the Pi's PPS output, which has the benefit of making the entire system run on the same (very) exact time.  Would I need to add an RTC to the FYSETC?

Second question related to micro-stepping -  suggestions for best combination of tracking/slewing micro-steps?  I have it running now with 32/8 (slews are very fast).  Any reason not to try 64/8 or even 128/8?  Theoretical accuracy gain, but does that translate to a measurable improvement in actual performance?

A few pics follow - I'll send a completed build set, and final 3d print files to the list when complete. 



Brian Davis
 

Chad, check out this page: https://indilib.org/support/tutorials/157-persistent-serial-port-mapping.html

It discusses the way to map your usb serial devices to individual names, so you can plug them all in at the same time.

On Tue, Jun 1, 2021 at 7:46 PM Chad Gray <rchadgray@...> wrote:
Hi Brian, i do not have an answer for you, but i do have a RaspberryPi/GPS question.  :)

I also have the Adafruit GPS plugged in via the GPIO pins.  I have it setup to have PPS be the time source. I followed this guide.

My problem is if i plug in a USB device (ZWO camera, Celestron Nextstar, ZWO focuser, QHY guide scope) to the Raspberry Pi i lose my GPS!  It has to do with the serial port, but i do not know what to start doing to debug it and find a fix to always have the GPS on /dev/ttys0

If you want to take this off the list you can email me direct.

Thanks!
Chad

On Tue, Jun 1, 2021 at 8:09 PM Brian Davis <tapperbld@...> wrote:
So, I'm closing in on my CGEM build, largely done following Francois Buechard and Chris Vaghn's build details.  I recently picked up a FYSTEC S6/TMC2130s, and left the MKS GEN-L board for another project.  My build also includes a Raspberry Pi 4b4g, which runs INDI (Stellarmate), and has an attached ADAFruit GPS with it's PPS output driving a pin on the PI tied to /dev/pps0.  The PI is running a fully configured NTP server, and rates as a Stratum 1 timeserver - meaning it is a serious reference time source.  (I actually compared it's accuracy to a Spectracom rubidium timeserver I had left from a commercial radio system - and the Pi is not much less accurate!).

Which begs the question - how can I best use the accuracy of the time source  to regulate time on the FYSETC?  I can tie to a pin on the Pi I think by linking a GPIO pin to the /dev/pps0 output, and use INDI to set time on Onstep (on the FYSETC)?   I'd like to use the Pi's PPS output, which has the benefit of making the entire system run on the same (very) exact time.  Would I need to add an RTC to the FYSETC?

Second question related to micro-stepping -  suggestions for best combination of tracking/slewing micro-steps?  I have it running now with 32/8 (slews are very fast).  Any reason not to try 64/8 or even 128/8?  Theoretical accuracy gain, but does that translate to a measurable improvement in actual performance?

A few pics follow - I'll send a completed build set, and final 3d print files to the list when complete. 



Chad Gray
 

Thanks Brian!  I will check it out!  I think you are right... this is the key.

I was all excited when i got PPS running and the time was deadly accurate.  Then I plugged my other devices in and I lost my excitement and GPS.  LOL

The way i use the GPS is in K-Stars/Ekos i set polling to 60 seconds to check GPSD for current time. 

image.png


On Wed, Jun 2, 2021 at 9:42 AM Brian Davis <tapperbld@...> wrote:
Chad, check out this page: https://indilib.org/support/tutorials/157-persistent-serial-port-mapping.html

It discusses the way to map your usb serial devices to individual names, so you can plug them all in at the same time.

On Tue, Jun 1, 2021 at 7:46 PM Chad Gray <rchadgray@...> wrote:
Hi Brian, i do not have an answer for you, but i do have a RaspberryPi/GPS question.  :)

I also have the Adafruit GPS plugged in via the GPIO pins.  I have it setup to have PPS be the time source. I followed this guide.

My problem is if i plug in a USB device (ZWO camera, Celestron Nextstar, ZWO focuser, QHY guide scope) to the Raspberry Pi i lose my GPS!  It has to do with the serial port, but i do not know what to start doing to debug it and find a fix to always have the GPS on /dev/ttys0

If you want to take this off the list you can email me direct.

Thanks!
Chad

On Tue, Jun 1, 2021 at 8:09 PM Brian Davis <tapperbld@...> wrote:
So, I'm closing in on my CGEM build, largely done following Francois Buechard and Chris Vaghn's build details.  I recently picked up a FYSTEC S6/TMC2130s, and left the MKS GEN-L board for another project.  My build also includes a Raspberry Pi 4b4g, which runs INDI (Stellarmate), and has an attached ADAFruit GPS with it's PPS output driving a pin on the PI tied to /dev/pps0.  The PI is running a fully configured NTP server, and rates as a Stratum 1 timeserver - meaning it is a serious reference time source.  (I actually compared it's accuracy to a Spectracom rubidium timeserver I had left from a commercial radio system - and the Pi is not much less accurate!).

Which begs the question - how can I best use the accuracy of the time source  to regulate time on the FYSETC?  I can tie to a pin on the Pi I think by linking a GPIO pin to the /dev/pps0 output, and use INDI to set time on Onstep (on the FYSETC)?   I'd like to use the Pi's PPS output, which has the benefit of making the entire system run on the same (very) exact time.  Would I need to add an RTC to the FYSETC?

Second question related to micro-stepping -  suggestions for best combination of tracking/slewing micro-steps?  I have it running now with 32/8 (slews are very fast).  Any reason not to try 64/8 or even 128/8?  Theoretical accuracy gain, but does that translate to a measurable improvement in actual performance?

A few pics follow - I'll send a completed build set, and final 3d print files to the list when complete.