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1
Mount Support / Re: Green Swamp Software GS Server
« on: September 02, 2022, 15:36:45 »
Hi Tom,
I just had cause to update another of my Astro-EQs and I notice that the latest config utility in the downloads folder on GitHub is not actually the latest. It is firmware 8.18 not 8.20. Luckily I found this thread so could use the hex.zip in includes to update to 8.19 which I think will fix my problem.
Kind regards,
Phil
I just had cause to update another of my Astro-EQs and I notice that the latest config utility in the downloads folder on GitHub is not actually the latest. It is firmware 8.18 not 8.20. Luckily I found this thread so could use the hex.zip in includes to update to 8.19 which I think will fix my problem.
Kind regards,
Phil
2
Mount Support / Re: Green Swamp Software GS Server
« on: January 04, 2021, 09:47:56 »
Hi Tom,
Your fix worked. Thank you for the quick response.
Kind regards,
Phil
Your fix worked. Thank you for the quick response.
Kind regards,
Phil
3
Mount Support / Green Swamp Software GS Server
« on: January 01, 2021, 21:47:57 »
Hi Tom,
I am currently investigating and testing moving over to a new ASCOM driver for SkyWatcher mounts from Green Swamp Software called GS Server. This is being actively developed, unlike EQMOD and the code base is readily available on Github and written using .NET.
So far I have only come across one problem. Unlike EQMOD which sends an AxisStop (:K) whenever the slew speed changes GS Server only sends a :K command if the slew direction is changing or if you are going from highspeed to lowspeed.
The upshot of this is that if the mount is already tracking and you attempt a slow slew with the RA axis in it's normal direction the slew does not start. Additionally, once you do manage to get it slewing at low speed in the RA direction and attempt to return to sidereal rate the mount continues at the slow slew speed.
I have spoken to Rob Morgan the author and he would prefer to keep his code matching the Skywatcher rules and apparently Skywatcher mounts do not need the :K command if only the speed and not the direction is being changed. They just require the :I command.
Is there a reason why the Astro EQ firmware requires a :K when only the speed is changing. How difficult would this be to change?
If it is possible to change the firmware I am sure I am not the only person who would like to finally have an alternative to EQMOD.
To illustrate I have attached a log dump for GS Server showing the commands being sent to the mount. I have commented the lines to help understand what is going on.
Kind regards and Happy 2021
Phil
p.s. You can find GS Server here:
https://sites.google.com/view/greenswamp/
and on Facebook.
I am currently investigating and testing moving over to a new ASCOM driver for SkyWatcher mounts from Green Swamp Software called GS Server. This is being actively developed, unlike EQMOD and the code base is readily available on Github and written using .NET.
So far I have only come across one problem. Unlike EQMOD which sends an AxisStop (:K) whenever the slew speed changes GS Server only sends a :K command if the slew direction is changing or if you are going from highspeed to lowspeed.
The upshot of this is that if the mount is already tracking and you attempt a slow slew with the RA axis in it's normal direction the slew does not start. Additionally, once you do manage to get it slewing at low speed in the RA direction and attempt to return to sidereal rate the mount continues at the slow slew speed.
I have spoken to Rob Morgan the author and he would prefer to keep his code matching the Skywatcher rules and apparently Skywatcher mounts do not need the :K command if only the speed and not the direction is being changed. They just require the :I command.
Is there a reason why the Astro EQ firmware requires a :K when only the speed is changing. How difficult would this be to change?
If it is possible to change the firmware I am sure I am not the only person who would like to finally have an alternative to EQMOD.
To illustrate I have attached a log dump for GS Server showing the commands being sent to the mount. I have commented the lines to help understand what is going on.
Kind regards and Happy 2021
Phil
p.s. You can find GS Server here:
https://sites.google.com/view/greenswamp/
and on Facebook.
4
Capabilities Question / Wireless RS232 Bluetooth Serial Adapter
« on: March 19, 2019, 09:23:44 »
Does anyone have any experience using something like this:
http://www.irxon.com/english/products/bt578_e.htm
as a bluetooth replacement for the USB cable assuming that an adaptor/cable could be created from a 9 pin serial socket to a Mini USB plug. Possibly using the PWR out on an AstroEQ to power it?
Or, alternatively, have any of the Arduino gurus out there built something to act as a bluetooth replacement for the USB cable? Is that even possible?
Kind regards,
Phil
http://www.irxon.com/english/products/bt578_e.htm
as a bluetooth replacement for the USB cable assuming that an adaptor/cable could be created from a 9 pin serial socket to a Mini USB plug. Possibly using the PWR out on an AstroEQ to power it?
Or, alternatively, have any of the Arduino gurus out there built something to act as a bluetooth replacement for the USB cable? Is that even possible?
Kind regards,
Phil
5
DIY AstroEQ / Config utility V8.03 onwards problems with Arduino Mega
« on: February 11, 2018, 16:14:45 »
Hi Tom,
I have just tried configuring my original Arduino Mega Astro-EQ with version 8.05 of the configuration utility and following configuration the AstroEQ does not work correctly with EQMOD. If you try connecting to EQMOD, either via ASCOM Toolbox or at the end of the config utility, the status light starts to flash rapidly and EQMOD is unresponsive. Sometimes you get a timeout error. After EQMOD is closed the status light continues flashing rapidly. The only way to stop this is to disconnect power and USB.
Reverting to Version 7.4 of the config utility fixes the issue after you update firmware and do the eprom fix etc. Should version 8 work OK with Arduino Mega versions.
Phil
I tried version 8.03, 8.05 and 8.11. All had the same effect.
I have just tried configuring my original Arduino Mega Astro-EQ with version 8.05 of the configuration utility and following configuration the AstroEQ does not work correctly with EQMOD. If you try connecting to EQMOD, either via ASCOM Toolbox or at the end of the config utility, the status light starts to flash rapidly and EQMOD is unresponsive. Sometimes you get a timeout error. After EQMOD is closed the status light continues flashing rapidly. The only way to stop this is to disconnect power and USB.
Reverting to Version 7.4 of the config utility fixes the issue after you update firmware and do the eprom fix etc. Should version 8 work OK with Arduino Mega versions.
Phil
I tried version 8.03, 8.05 and 8.11. All had the same effect.
6
Hardware Development / Re: AstroEQ Basic Hand Controllers
« on: February 05, 2018, 21:32:57 »
Hello as part of my Astro-EQ6 conversion I wanted to re-use the old hand controller that came with the non-working, non-goto EQ6 that I started with. This was a relatively easy hack. I simply de-soldered and remove all the components except the 4 momentary switches and the slide switches from the original controller. I also un-soldered the curly cable which just happened to have a 6 contact RJ11 (also known as an RJ12) connector.
You can't see it in the picture but the 3K9 speed control resistor replaced the left-hand resistor under the ribbon cable you can see in the attached picture. I stripped back the outer insulation of the cable to expose the two unused wires and reconnected the individual wires as you can see the picture. I also added a blue and brown jumpers that you can see crossing the old IC location. The de-bounce capacitors were soldered directly to the back of the momentary switches.
The original 2x, 8x, 16x switch controls the speed. The other switch does nothing. Make sure you also remove the LED from the centre of the RA/DEC keys otherwise the high-speed slew doesn't work.
Phil
You can't see it in the picture but the 3K9 speed control resistor replaced the left-hand resistor under the ribbon cable you can see in the attached picture. I stripped back the outer insulation of the cable to expose the two unused wires and reconnected the individual wires as you can see the picture. I also added a blue and brown jumpers that you can see crossing the old IC location. The de-bounce capacitors were soldered directly to the back of the momentary switches.
The original 2x, 8x, 16x switch controls the speed. The other switch does nothing. Make sure you also remove the LED from the centre of the RA/DEC keys otherwise the high-speed slew doesn't work.
Phil
7
Mount Support / Re: NEMA 17 Goto speed help
« on: February 05, 2018, 21:14:19 »
Final reply from me just to confirm that I now have the EQ6 slewing nicely at 325x, no sign of missed steps or sudden stops and working with 32 uSteps and uStep gearing enabled. The figures from the spreadsheet I posted in an early reply seem to reflect what happens in practice.
If anyone is interested the stepper motors I ended up with were from OMC Stepper online part number: 17HM19-1684S. 2.8V, 1.68A (running them at 1.2A), holding torque 0.44Nm and a 0.9 degree step angle.
The moral to this story is do your sums first. Calculate the rotational speed you will need from the stepper motor to slew at sidereal rate with your gearing. Then do the maths for a range of stepper motors to find out which one gives you the best slew speed for your available voltage and current.
Anyone want my reject stepper motors, very little used but not suitable 325x EQ6 speeds?
Phil
If anyone is interested the stepper motors I ended up with were from OMC Stepper online part number: 17HM19-1684S. 2.8V, 1.68A (running them at 1.2A), holding torque 0.44Nm and a 0.9 degree step angle.
The moral to this story is do your sums first. Calculate the rotational speed you will need from the stepper motor to slew at sidereal rate with your gearing. Then do the maths for a range of stepper motors to find out which one gives you the best slew speed for your available voltage and current.
Anyone want my reject stepper motors, very little used but not suitable 325x EQ6 speeds?
Phil
8
Mount Support / Re: NEMA 17 Goto speed help
« on: January 30, 2018, 10:25:10 »
I have been doing some research and have come across the following page which has increased my understanding of stepper motors quite a bit.
https://www.duet3d.com/wiki/Choosing_stepper_motors
I have created a spreadsheet using the formulae given in the article for calculating the power supply voltage required for various slew rates with a range of stepper motors. See the attachment to this post.
I realise now that I have been looking at this the wrong way around. According to the article the limiting factor for a stepper motors rotational speed at a constant available current is the supply voltage. So my aim of 800X as per my EQ5 is unrealistic on the EQ6, as pointed out by Victor in another reply. The gearing would lead to the stepper motor needing a supply voltage of around 50V to overcome the back EMF due to rotation and inductance. Since my supply voltage is around 12V the best slew rate I can expect with the current motors is around 200X.
The spreadsheet does suggest, however, that speeds of around 300X should be possible with different stepper motors. I wish I had found the article earlier.
Phil
https://www.duet3d.com/wiki/Choosing_stepper_motors
I have created a spreadsheet using the formulae given in the article for calculating the power supply voltage required for various slew rates with a range of stepper motors. See the attachment to this post.
I realise now that I have been looking at this the wrong way around. According to the article the limiting factor for a stepper motors rotational speed at a constant available current is the supply voltage. So my aim of 800X as per my EQ5 is unrealistic on the EQ6, as pointed out by Victor in another reply. The gearing would lead to the stepper motor needing a supply voltage of around 50V to overcome the back EMF due to rotation and inductance. Since my supply voltage is around 12V the best slew rate I can expect with the current motors is around 200X.
The spreadsheet does suggest, however, that speeds of around 300X should be possible with different stepper motors. I wish I had found the article earlier.
Phil
9
Mount Support / Re: NEMA 17 Goto speed help
« on: January 29, 2018, 13:21:41 »
Hi Tom,
The sudden stops after initial movement seems to go away if I DISABLE uStep gearing in the Config utility. I am using the latest version of the config utility from the links on the download page (8.05).
I managed to get the mount slewing by disabling the uStep gearing and loosening the worm backlash (i.e. at the cost of having backlash present) but I can still hear the odd missed step. Could part of my problem be that the Stepper motors simply do not have enough torque?
The ones that are in now supposedly have a holding torque of 0.36Nm (51oz.in.) the same as the SW NEMA 17 steppers in the modern EQ6 mounts (according to a post on the international astronomy forum).
My knowledge of stepper motors is limited. Is it better to have a stepper with a much lower rated voltage than 12V but higher current or vic versa?
Is holding torque important when what we are actually after is acceleration/deceleration and constant velocity without missed steps?
So far I have tried:
12v/0.40a/1.8deg/0.40Nm; and,
5.4v/0.90a/0.9deg/0.36Nm (the current ones)
Other options I could try are:
2.8V/1.68a/1.8deg/0.45Nm;
10V/0.64a/1.8deg/0.60Nm;
7.2V/1.2a/1.8deg/0.65Nm (but 6 wires and only available shipped from China)
I am loath to keep spending money on stepper motors to find out which is most suitable by trial and error. Can anyone give me any guidance to help me choose?
Thanks.
Phil
The sudden stops after initial movement seems to go away if I DISABLE uStep gearing in the Config utility. I am using the latest version of the config utility from the links on the download page (8.05).
I managed to get the mount slewing by disabling the uStep gearing and loosening the worm backlash (i.e. at the cost of having backlash present) but I can still hear the odd missed step. Could part of my problem be that the Stepper motors simply do not have enough torque?
The ones that are in now supposedly have a holding torque of 0.36Nm (51oz.in.) the same as the SW NEMA 17 steppers in the modern EQ6 mounts (according to a post on the international astronomy forum).
My knowledge of stepper motors is limited. Is it better to have a stepper with a much lower rated voltage than 12V but higher current or vic versa?
Is holding torque important when what we are actually after is acceleration/deceleration and constant velocity without missed steps?
So far I have tried:
12v/0.40a/1.8deg/0.40Nm; and,
5.4v/0.90a/0.9deg/0.36Nm (the current ones)
Other options I could try are:
2.8V/1.68a/1.8deg/0.45Nm;
10V/0.64a/1.8deg/0.60Nm;
7.2V/1.2a/1.8deg/0.65Nm (but 6 wires and only available shipped from China)
I am loath to keep spending money on stepper motors to find out which is most suitable by trial and error. Can anyone give me any guidance to help me choose?
Thanks.
Phil
10
Mount Support / Re: NEMA 17 Goto speed help
« on: January 25, 2018, 14:20:42 »
The new stepper motors arrived. They are 0.9A per phase so I set the current limit voltage to 0.45V on the drivers and they behaved just the same as the previous motors when trying to slew in EQMOD at 800X under no load.
A friend at my astronomy society told me he had the same problem when doing his EQ5 and that he had to turn the current limit down below the recommended setting to get the motors to work. So I gave this a try and hey presto the new motors now spin up to full speed on the bench under no load. I actually ended up setting the current limiting voltage to 0.2V. I don't understand the logic to this but just in case someone has the same problem I have posted what I did to get mine working.
I will test them in the mount this evening. I'll be back if I still have problem.
A friend at my astronomy society told me he had the same problem when doing his EQ5 and that he had to turn the current limit down below the recommended setting to get the motors to work. So I gave this a try and hey presto the new motors now spin up to full speed on the bench under no load. I actually ended up setting the current limiting voltage to 0.2V. I don't understand the logic to this but just in case someone has the same problem I have posted what I did to get mine working.
I will test them in the mount this evening. I'll be back if I still have problem.
11
Mount Support / Re: Gears,gears,gears
« on: January 23, 2018, 14:17:01 »
Terry,
Depending on your budget you might want to look at using the Rowan Astronomy belt drive kit.
http://www.rowanastronomy.com/productsa2.htm
This replaces the gears completely and provides mountings for NEMA 17 stepper motors. I have attached a picture of my motors in an early non-goto EQ6.
[NOTE: Don't use the steppers in the picture, I had issues with them after I took the picture]
Depending on your budget you might want to look at using the Rowan Astronomy belt drive kit.
http://www.rowanastronomy.com/productsa2.htm
This replaces the gears completely and provides mountings for NEMA 17 stepper motors. I have attached a picture of my motors in an early non-goto EQ6.
[NOTE: Don't use the steppers in the picture, I had issues with them after I took the picture]
12
Mount Support / Re: Converting early EQ6 mount
« on: January 22, 2018, 22:11:12 »
Photo of the mount showing the replacement cover plate with sockets for the RA and Dec cables.
13
Mount Support / Re: Converting early EQ6 mount
« on: January 22, 2018, 22:08:23 »How are you mounting the NEMA motors as if you just bolt them to the old plates and use the single cog it looks as though it will miss the internal tooted cog in the mount.
The Rowan Astronomy belt conversion bolts to the same mount holes as the original stepper motor mounting plates. That bit of the project went like a dream. See my picture else where in this thread.
14
Mount Support / Re: NEMA 17 Goto speed help
« on: January 22, 2018, 22:02:19 »
In case anyone is following along ...
This evening I have taken the 12V 0.4A 1.8deg steppers out of the mount and tested them on the bench.
I have fixed the missed step by making the rapid decay mod to the DRV8825s by putting a solder bridge across the DECAY and FAULT pins on the ICs as suggested in another post.
The problem with high speed slews from EQMOD remains. If I try and slew at anything above 501X the motor starts to turn up to speed but then stops suddenly until the button is released at which point it seems to complete the deceleration stage as if it had been moving.
I have also done some more research on stepper voltages and I now realise that it is actually better to drive the steppers with a higher voltage that their rated value (up to 20x greater apparently according to this http://blog.inventables.com/p/stepper-motors.html).
Also, I should have realised that going for 12V steppers isn't a good idea since I drive the mount off a 12V battery so the voltage drops as the night progresses.
With this in mind I have ordered two of these (https://www.omc-stepperonline.com/hybrid-stepper-motor/nema-17-bipolar-09deg-36ncm-51ozin-09a-54v-42x42x40mm-4-wires-17hm15-0904s.html). I hope they do the trick.
Phil
This evening I have taken the 12V 0.4A 1.8deg steppers out of the mount and tested them on the bench.
I have fixed the missed step by making the rapid decay mod to the DRV8825s by putting a solder bridge across the DECAY and FAULT pins on the ICs as suggested in another post.
The problem with high speed slews from EQMOD remains. If I try and slew at anything above 501X the motor starts to turn up to speed but then stops suddenly until the button is released at which point it seems to complete the deceleration stage as if it had been moving.
I have also done some more research on stepper voltages and I now realise that it is actually better to drive the steppers with a higher voltage that their rated value (up to 20x greater apparently according to this http://blog.inventables.com/p/stepper-motors.html).
Also, I should have realised that going for 12V steppers isn't a good idea since I drive the mount off a 12V battery so the voltage drops as the night progresses.
With this in mind I have ordered two of these (https://www.omc-stepperonline.com/hybrid-stepper-motor/nema-17-bipolar-09deg-36ncm-51ozin-09a-54v-42x42x40mm-4-wires-17hm15-0904s.html). I hope they do the trick.
Phil
15
Mount Support / Re: NEMA 17 Goto speed help
« on: January 22, 2018, 09:33:22 »
I have been doing some more reading on here and wonder whether my problems are related to the DRV8825 mixed mode decay.
In review, I have two symptoms:
1. If, in EQMOD, I try slewing at 800x I hear the stepper motors accelerating briefly then they stop and make a louder noise for as long as I hold the button down in EQMOD. When I release the button I hear the stepper motor decelerate.
2. When tracking at sidereal speed in 1/32 uStep mode I can here missed steps every second.
Reading other posts on here and articles elsewhere, symptom 2 sounds like I need to do the fast decay mod. Would symptom 1 also be expected from an unmodified DRV8825 running in 1/32 uStep mode?
My next problem is that the original blogpost that people link to explaining how to do the fast decay modification is no longer online. Please can someone explain what I need to do or point me to link that is still up and working.
Also, where can I find information on the "diode" modification in case I need to do this. Again, the links in the original posts no longer seem to be working.
Finally, would I have been better going for a stepper motor with a lower rated voltage? In my ignorance I just assumed that I should go for a 12v rated stepper. I have since seen a post on SGL where someone says that it is important to have a motor supply voltage that is much larger than the steppers rated voltage.
Thanks again,
Phil
In review, I have two symptoms:
1. If, in EQMOD, I try slewing at 800x I hear the stepper motors accelerating briefly then they stop and make a louder noise for as long as I hold the button down in EQMOD. When I release the button I hear the stepper motor decelerate.
2. When tracking at sidereal speed in 1/32 uStep mode I can here missed steps every second.
Reading other posts on here and articles elsewhere, symptom 2 sounds like I need to do the fast decay mod. Would symptom 1 also be expected from an unmodified DRV8825 running in 1/32 uStep mode?
My next problem is that the original blogpost that people link to explaining how to do the fast decay modification is no longer online. Please can someone explain what I need to do or point me to link that is still up and working.
Also, where can I find information on the "diode" modification in case I need to do this. Again, the links in the original posts no longer seem to be working.
Finally, would I have been better going for a stepper motor with a lower rated voltage? In my ignorance I just assumed that I should go for a 12v rated stepper. I have since seen a post on SGL where someone says that it is important to have a motor supply voltage that is much larger than the steppers rated voltage.
Thanks again,
Phil