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1
DIY AstroEQ / Re: mega pro mini
« on: June 07, 2020, 10:21:18 »
The pro cards run at the same clock speed.
I think having the phone type USB port is worth the extra few mm.
Paul
I think having the phone type USB port is worth the extra few mm.
Paul
2
DIY AstroEQ / Re: Increasing motor speeds with Mega 2560
« on: June 07, 2020, 10:12:49 »
If it is open source, rewrite the code to ramp up the *acceleration* slowly.
It's likely the motors are stalling on the high rotational inertia. A slow siredal start, gradually speeding up over 10 to 20 seconds may help.
The code might already do that, but was tuned to a lighter scope with a step gear change I think.
CNCs have programmable ramp up times and max speed to avoid losing sync.
Steppers with encoders and controllers are becoming cheap. Theoretically they won't loose sync at any speed.
But as Tom said, try 36V or even 48V first.
Thinking ahead, potentiometers for acceleration and top speed on 2 Arduino analog pins could be useful to tune in real time.
Paul
It's likely the motors are stalling on the high rotational inertia. A slow siredal start, gradually speeding up over 10 to 20 seconds may help.
The code might already do that, but was tuned to a lighter scope with a step gear change I think.
CNCs have programmable ramp up times and max speed to avoid losing sync.
Steppers with encoders and controllers are becoming cheap. Theoretically they won't loose sync at any speed.
But as Tom said, try 36V or even 48V first.
Thinking ahead, potentiometers for acceleration and top speed on 2 Arduino analog pins could be useful to tune in real time.
Paul
3
DIY AstroEQ / Reliable 12V connection?
« on: April 02, 2019, 09:51:03 »
My board continued to track RA all night on my test bench, with minimal heating of the stepper. All good.
The problem I have is that the 12V connection is unreliable, a brief interruption in 12V will crash the CPU and lose connection with ASCOM.
Has anyone used a locking 12V connection? I think a locking power connector is essential in an outdoor environment. The common DC power plug can easily be pulled out accidentally - at exactly the wrong time!
One option is to solder wires to the 12V input on the PCB, about 6in long. Then fit a good quality RC power connector like the XT30.
Does anyone have any recommendations for a reliable power connection?
Paul
The problem I have is that the 12V connection is unreliable, a brief interruption in 12V will crash the CPU and lose connection with ASCOM.
Has anyone used a locking 12V connection? I think a locking power connector is essential in an outdoor environment. The common DC power plug can easily be pulled out accidentally - at exactly the wrong time!
One option is to solder wires to the 12V input on the PCB, about 6in long. Then fit a good quality RC power connector like the XT30.
Does anyone have any recommendations for a reliable power connection?
Paul
4
DIY AstroEQ / Re: Sidereal Tracking: motor oscillates forwards then backwards
« on: April 01, 2019, 17:55:00 »
Everything seems to be working well now. Best setting for my motors are:
Step Modes: Slow = 8 usteps/stp, Fast = 1 ustep/stp
With no load, the fastest rate without stalling is 650x
-Paul
Step Modes: Slow = 8 usteps/stp, Fast = 1 ustep/stp
With no load, the fastest rate without stalling is 650x
-Paul
5
DIY AstroEQ / Re: Sidereal Tracking: motor oscillates forwards then backwards
« on: April 01, 2019, 12:19:30 »
Tom,
Update: I've just realised there are different pin-outs for A498x and DRV882x. But I had assumed they were compatible, and did not notice the "Pin name format" comment.
-Paul
Update: I've just realised there are different pin-outs for A498x and DRV882x. But I had assumed they were compatible, and did not notice the "Pin name format" comment.
-Paul
6
DIY AstroEQ / Re: Sidereal Tracking: motor oscillates forwards then backwards
« on: April 01, 2019, 12:03:47 »
Thanks Tom,
I checked the wiring and deduced xABABx was correct for the RJ45 by looking at the schematic. The labelling is:
RA_1B
RA_2A
RA_2B
RA_1A
which I assumed was coils A and B, connections 1 and 2.
However your reply, correct I'm sure, implies coils 1 and 2, connections A and B. Brexit is clearer ha ha
I ran a quick Arduino + motor board test (https://www.instructables.com/id/Stepper-Motor-Test-With-Arduino-Using-Arduino-Moto/). The motor rotates smoothly on 5V supplied by my laptop, on all 4 stepping modes, slower RPM on micro-stepping. But on 12V it runs rough and stutters a bit on the DOUBLE setting.
The Nema 14 motor ratings are:
Phase current 0.8 A
Phase resistance 6.8 ohm
Phase inductance 10 mh
Rated voltage 5.4 V
The shield driver runs hot on 12V, too hot. The rough performance maybe current saturation in the switching supply limited to 1A
I'll rewire the motor correctly for the AstroEQ and report back.
Many thanks,
Paul
I checked the wiring and deduced xABABx was correct for the RJ45 by looking at the schematic. The labelling is:
RA_1B
RA_2A
RA_2B
RA_1A
which I assumed was coils A and B, connections 1 and 2.
However your reply, correct I'm sure, implies coils 1 and 2, connections A and B. Brexit is clearer ha ha
I ran a quick Arduino + motor board test (https://www.instructables.com/id/Stepper-Motor-Test-With-Arduino-Using-Arduino-Moto/). The motor rotates smoothly on 5V supplied by my laptop, on all 4 stepping modes, slower RPM on micro-stepping. But on 12V it runs rough and stutters a bit on the DOUBLE setting.
The Nema 14 motor ratings are:
Phase current 0.8 A
Phase resistance 6.8 ohm
Phase inductance 10 mh
Rated voltage 5.4 V
The shield driver runs hot on 12V, too hot. The rough performance maybe current saturation in the switching supply limited to 1A
I'll rewire the motor correctly for the AstroEQ and report back.
Many thanks,
Paul
7
DIY AstroEQ / Sidereal Tracking: motor oscillates forwards then backwards
« on: March 31, 2019, 16:43:07 »
I built the Astro EQ PCB a few years ago - the interface chip is labelled "AstroEQ-USB 27/03/17" I used DRV882x drivers, allegedly from Pololu. The latest firmware was downloaded/uploaded yesterday.
On Sidereal tracking (32 steps) the motor steps forwards, then backward, then forwards, then backwards.......oscillating forever. Different motor current settings give different movements, but it always oscillates.
Sidereal with 1 step and 4 steps also oscillates.
Slewing oscillates, but at 800X the motor will spin. However it can spin in the other direction during the next slew! The direction of 800X spin seems to vary according to where it stopped. Also it oscillates until the software has ramped up to almost full speed, then it spins.
I wonder if I have cooked the motor? It did get very hot, then I realised the wiring was wrong and I may have had the two phases in series for a while. OOps
.
Perhaps the driver(s) is damaged?
Would current/voltage limiting in the power supply cause oscillation? It is rated at 1A, but I have not measured the voltage when the motor steps.
Something is very wrong, as the motor is not under load. I'm testing it on the workbench with a bit of tape on the shaft.
I wonder if a stepper motor test circuit is worth building? I think I have an L293 shield for the Arduino somewhere.
Any help is appreciated.
On Sidereal tracking (32 steps) the motor steps forwards, then backward, then forwards, then backwards.......oscillating forever. Different motor current settings give different movements, but it always oscillates.
Sidereal with 1 step and 4 steps also oscillates.
Slewing oscillates, but at 800X the motor will spin. However it can spin in the other direction during the next slew! The direction of 800X spin seems to vary according to where it stopped. Also it oscillates until the software has ramped up to almost full speed, then it spins.
I wonder if I have cooked the motor? It did get very hot, then I realised the wiring was wrong and I may have had the two phases in series for a while. OOps
. Perhaps the driver(s) is damaged?
Would current/voltage limiting in the power supply cause oscillation? It is rated at 1A, but I have not measured the voltage when the motor steps.
Something is very wrong, as the motor is not under load. I'm testing it on the workbench with a bit of tape on the shaft.
I wonder if a stepper motor test circuit is worth building? I think I have an L293 shield for the Arduino somewhere.
Any help is appreciated.
8
DIY AstroEQ / Re: Update Utility fails with Mega 2560 on Windows 10
« on: May 12, 2017, 16:25:16 »Hmm. What command did you use to burn it?
I used eXtreme Burner - AVR 1.4, after smuggling an unsigned driver into Windows 10 with Shift + Reset, which on startup allows many special modes, like "allow Alien device drivers".
I thought erasing the chip would be a clean start (ha-ha), but it blows away the eeprom, flash and fuses. I did my best to select the external Crystal oscillator. I should have Read all 3 sets of data and made a backup, but that's life!
cheers
-Paul
9
DIY AstroEQ / Re: Update Utility fails with Mega 2560 on Windows 10
« on: May 12, 2017, 15:37:49 »
Tom I've only just read your message.
But I decided I had to learn avrdude, so I installed it and eventually got the USBasp programmer to program the board via the 6-pin ISP with this command:
avrdude -c usbasp -u -U flash:w:stk500boot_V2_mega250.hex
There seems to be no need for fuse settings as avrdude works in "safe mode" by default. I think it sets default xtal fuse settings, but I'm not 100% sure.
Zadig 2.3 is an excellent signed driver for USBasp drivers and more. I installed libusb-win32 (v 1.2.6.0) which is an open source USB driver library, which mounted the USBasp programmer as a USB device. Its a cheap programmer, under £5, a Chinese clone of the original design (I think) by Thomas Fischl:
http://www.fischl.de/usbasp/
Then I could run your Install Utility, but Java seemed to hang after firmware upload so I killed the install. Then started install to read the EEprom which was empty, I programmed the EQ5-belt config and the data uploaded ok.
Yes the long way round, but I learnt a lot and feel quite proud. But thanks for your suggestion.
cheers
Paul
But I decided I had to learn avrdude, so I installed it and eventually got the USBasp programmer to program the board via the 6-pin ISP with this command:
avrdude -c usbasp -u -U flash:w:stk500boot_V2_mega250.hex
There seems to be no need for fuse settings as avrdude works in "safe mode" by default. I think it sets default xtal fuse settings, but I'm not 100% sure.
Zadig 2.3 is an excellent signed driver for USBasp drivers and more. I installed libusb-win32 (v 1.2.6.0) which is an open source USB driver library, which mounted the USBasp programmer as a USB device. Its a cheap programmer, under £5, a Chinese clone of the original design (I think) by Thomas Fischl:
http://www.fischl.de/usbasp/
Then I could run your Install Utility, but Java seemed to hang after firmware upload so I killed the install. Then started install to read the EEprom which was empty, I programmed the EQ5-belt config and the data uploaded ok.
Yes the long way round, but I learnt a lot and feel quite proud. But thanks for your suggestion.
cheers
Paul
10
DIY AstroEQ / Re: Update Utility fails with Mega 2560 on Windows 10
« on: May 11, 2017, 20:55:38 »
I bought a USBasp programmer from Ebay, programmed the new hex file into my Mega 2560 with eXtreme Burner AVR........and its as dead as a do-do. I don't think the oscillator runs as the Reset button doesn't cause any LEDs to flicker.
Maybe the complete chip erase was not so wise. I have to dig around to understand the oscillator settings and powerup settings.
Joy!
-Paul
Maybe the complete chip erase was not so wise. I have to dig around to understand the oscillator settings and powerup settings.
Joy!
-Paul
11
DIY AstroEQ / Re: Update Utility fails with Mega 2560 on Windows 10
« on: May 08, 2017, 21:01:14 »
I could not get the Arduino ISP to work (using a Uno) to re-program the Mega bootloader. Due to avrdude error "unknown device ID" aka Made in China. 
So I've more or less given up the idea as a waste of time. Maybe a simple ISP programmer from ebay will work.
So I've more or less given up the idea as a waste of time. Maybe a simple ISP programmer from ebay will work.
12
DIY AstroEQ / Re: EQMOD won't detect AstroEQ
« on: May 08, 2017, 20:22:14 »
Tom,
You deserve a medal for using Java! I'm a died-in-the-wool C++ man (Fortran if you want) and I like the compiler to find syntax errors and not the Customer!
We use a lot of Javascript in ArtCAM - www.artcam.com, but on the plus side the new one pound coin was designed with it.
Understood on all points. Regarding 2) I wanted to double check the correct uStep settings were uploaded, because after trying half a dozen combinations you can't see the wood for the trees. Maybe a simple text log is worth the effort, if other customers have asked for a log of some sorts. A human readable version of the .conf perhaps, saved as text with date+time. Just a thought. Bigger fish to fry.
regards
Paul
You deserve a medal for using Java! I'm a died-in-the-wool C++ man (Fortran if you want) and I like the compiler to find syntax errors and not the Customer!
We use a lot of Javascript in ArtCAM - www.artcam.com, but on the plus side the new one pound coin was designed with it.
Understood on all points. Regarding 2) I wanted to double check the correct uStep settings were uploaded, because after trying half a dozen combinations you can't see the wood for the trees. Maybe a simple text log is worth the effort, if other customers have asked for a log of some sorts. A human readable version of the .conf perhaps, saved as text with date+time. Just a thought. Bigger fish to fry.
regards
Paul
13
DIY AstroEQ / Re: Update Utility fails with Mega 2560 on Windows 10
« on: May 08, 2017, 18:33:13 »
Hi,
My typo. It's an Uno and I have found the Arduino ISP tutorial:
https://www.arduino.cc/en/Tutorial/ArduinoISP
cheers
Paul
My typo. It's an Uno and I have found the Arduino ISP tutorial:
https://www.arduino.cc/en/Tutorial/ArduinoISP
cheers
Paul
14
DIY AstroEQ / Re: Update Utility fails with Mega 2560 on Windows 10
« on: May 08, 2017, 16:06:08 »
Thanks Tom,
I'm not sure how to reprogram the MEGA, I tried using the Arduino IDE which no success.
I have a spare Arduino Duo, but Google throws up a lot of spaghetti that leads nowhere.....
-Paul
I'm not sure how to reprogram the MEGA, I tried using the Arduino IDE which no success.
I have a spare Arduino Duo, but Google throws up a lot of spaghetti that leads nowhere.....
-Paul
15
DIY AstroEQ / Update Utility fails with Mega 2560 on Windows 10
« on: May 08, 2017, 14:23:31 »
I can upload a simple blinking light demo project from the Arduino toolkit, to test the board
But I cannot make a successful transfer with the AstroEQ Installer.
1) Update Firmware. This starts the RX/TX lights flashing for several seconds, then avrdude seems to consume 100% cpu for several seconds. Pressing Next then starts reading the EEPROM, but no data is transferred and the RX/TX lights do not flash....then I get "Read Error! Connection Unavailable."
During the transfer there are several messages about "skipping pages", but I cannot scroll back to see the avrdude messages, using mouse, trackpad or cursor keys.
2) Configure. The "L" led flashes a few times, a few seconds later the RX LED blips quickly and everything does dead. Eventually the Utility times-out with the same error message.
In Device Manager the latest Arduino LLC driver is used V 1.2.2.0 dated 15/06/2015
I have tried a variety of UART speeds from 9600 to 115200, no change.
I updated JAVA to 1.8.0-123, no change.
It would appear that avrdude locks up or fails in some way.
cheers
Paul
But I cannot make a successful transfer with the AstroEQ Installer.
1) Update Firmware. This starts the RX/TX lights flashing for several seconds, then avrdude seems to consume 100% cpu for several seconds. Pressing Next then starts reading the EEPROM, but no data is transferred and the RX/TX lights do not flash....then I get "Read Error! Connection Unavailable."
During the transfer there are several messages about "skipping pages", but I cannot scroll back to see the avrdude messages, using mouse, trackpad or cursor keys.
2) Configure. The "L" led flashes a few times, a few seconds later the RX LED blips quickly and everything does dead. Eventually the Utility times-out with the same error message.
In Device Manager the latest Arduino LLC driver is used V 1.2.2.0 dated 15/06/2015
I have tried a variety of UART speeds from 9600 to 115200, no change.
I updated JAVA to 1.8.0-123, no change.
It would appear that avrdude locks up or fails in some way.
cheers
Paul
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