Hi everyone, I'm a bit confused about how to set the step mode for the solderless focus controller. Up to this point, I've been using the step mode drop down in the windows app, but today I realized that the documentation actually says it can't be set via software and that I have to use the jumpers on the stepper driver board.
I tried that tonight and got strange results while running some tests. In fact, I then tried experimenting with the step mode in the drop down as well, and that did seem to change behavior.
So, I'm just kinda confused. I'd prefer to set it via software, but what's the correct way?
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Hi
You can see from the attached diagram that step mode is set on the actual drv8825 board itself using jumpers.
The software does not prevent you from trying to change the step mode - or warn you that is cannot be changed.
Please also find attached the firmware for the Solderless drv8255
In the ino file starting at line 26 you will see
// CHANGE STEPMODE TO MATCH THE DRV8825 JUMPERS - only one line can be enabled//#define STEPMODE STEP1//#define STEPMODE STEP2
#defineSTEPMODESTEP4//#define STEPMODE STEP8//#define STEPMODE STEP16//#define STEPMODE STEP32
You need to dtermine the step mode on the little drv8825 board and then enable the correct line above. For example, if all slide switchers were off, this is a setting of full steps, so the lines would look like
// CHANGE STEPMODE TO MATCH THE DRV8825 JUMPERS - only one line can be enabled
#defineSTEPMODESTEP1//#define STEPMODE STEP2//#define STEPMODE STEP4//#define STEPMODE STEP8//#define STEPMODE STEP16//#define STEPMODE STEP32
Robert, thanks for your patience! I had entirely forgotten about the setting in the firmware. I will go give that a try here this morning.
It is really strange to me that changing the software setting had an impact. Not the desired impact, of course. It basically rotated the same amount, but with different levels of vibration.
Then, when approaching it through the jumpers on the board, I wound up with noise and vibration from the motor, but the shaft didn't turn at all.
So, I've messed up in several ways. :) Now, I'm off to set the jumpers on the board and tweak the definition in the firmware. This is all an attempt to get to quarter stepping for my 135mm lens that was discussed in a separate thread previously.
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OK, that firmware, configured for 1/4 steps, seems to be turning the shaft properly now. I'll have to wait for darker conditions to do any real testing.
I initially started to do that configuration with my existing firmware, but stepmode didn't exist in there. Is this something new coming with the 305 release?
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Hi Scott
Congrats on progress.
When the firmware has a fixed stepmode - like the file I posted for you, the software will not stop you trying to send a different step mode.
But if you follow that with a get stepmode - it will always return the same. It is the firmware that prevents the stepmode change - like the application sends to the controller please change to stepmode 16 and the controller, when it gets that request says to istelf, hell no. I cannot do that so simply ignores the request for a step mode change.
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Ah, gotcha. Makes sense. I'm gonna have a bit of a challenge no matter what though. I've got 3 different scopes and at least 2 different step modes required (I haven't been able to test out the SCT setup yet). Gonna be complicated if I have to upload firmware for every change.
I've gone on and ordered parts for the traditional, soldered unit. We'll see if I have the skills to pull it off. Who knows, maybe I'll just wind up with 3 controllers!
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I have dedicated focus controllers for each scope. Saves time because they all have their own custom settings. And no mucking around trying to figure out why focus does not work.
For the cost of building a focuser its way cheaper than the time taken to try and trouble shoot issues.
Talking about controllers, counting all the beta and other controllers for testing that I have - think of a high number and start multiplying. After all, the code has to be tested on each different controller, so needless to say a large number.
It always pays to have a spare. I remeber driving two hours to a dark site, started setting up everything, only to find I had no counterweights for the mount.
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Well, my PCBs arrived today. Other parts arriving by end of week. So, we'll see if I can get this figured out. :)
Fairly different question for you. When adjusting the pot on the driver board, would that setting be sensitive to the stepping mode? Testing the rig out tonight and the motor got super hot (in fact, warped my 3D printed carrier).
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Set the correct step mode you will be using first.
I like also to send a long move to the stepper( with stepper on the bench) and try to stop the motor shaft - it after tuning I can easily stop the shaft from turning, then its not enough and I add a little more to the pot.
The difference between not working - working - over hot is very minute - probably no more than 10 degrees of rotation?
If the motor gets hot - either the current is too high or you are using a different NEMA motor with a higher coil rating or with a lower voltage rating the ones recommmended
If it is a geared motor, then it is ok to have coil power off. I really do not like recommended coil power off when using microstepping. I prefer to run all the focusers at full steps by working out the correct parameters first (step size and 10 steps in cfz).
Running in full step mode means plenty of torque, no need to have coil power on.
Regards
Robert
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Hi Robert, I'm using the suggested NEMA14 motor on this rig. It is now set to run at 1/4 stepping.
I did follow the instructions for tuning the pot on the original setup which was driving the NEMA17-PG5 motor at half steps (although likely actually full steps given I had forgotten about the need to set the switches).
I have experimented with both coil power on and off with this rig. On certainly seems to be more consistent. I will attempt to tune the pot for this setup and see if I can get it dialed in.
I'll also be diving into building out more controllers soon. So, I'll tune each one specific to that rig.
Thanks again for the help!
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Hi Scott
All adjustments should be done with Coil Power set ON
This is becase the stepper move routines needs to turn coil power ON in order to move the stepper motor. In brief, it looks something like this
If Coil Power is OFF this is how it moves
- if coil power = off
- - turn it on to move the motor
- - step the motor in the required direction
- - pause for 2us minimum (minimum required step pulse length
- - delay a period of time (insert a delay between step pulses) to ensure the motor does not exceed its rated rpm speed)
- - repeat while more steps to do
- end of move
- restore original Coil Power state. if it was off before, turn it OFF
regards
Robert
If you would like to refer to this comment somewhere else in this project, copy and paste the following link:
Hi everyone, I'm a bit confused about how to set the step mode for the solderless focus controller. Up to this point, I've been using the step mode drop down in the windows app, but today I realized that the documentation actually says it can't be set via software and that I have to use the jumpers on the stepper driver board.
I tried that tonight and got strange results while running some tests. In fact, I then tried experimenting with the step mode in the drop down as well, and that did seem to change behavior.
So, I'm just kinda confused. I'd prefer to set it via software, but what's the correct way?
Hi
You can see from the attached diagram that step mode is set on the actual drv8825 board itself using jumpers.
The software does not prevent you from trying to change the step mode - or warn you that is cannot be changed.
Please also find attached the firmware for the Solderless drv8255
In the ino file starting at line 26 you will see
You need to dtermine the step mode on the little drv8825 board and then enable the correct line above. For example, if all slide switchers were off, this is a setting of full steps, so the lines would look like
Last edit: brownrb 2021-02-21
Robert, thanks for your patience! I had entirely forgotten about the setting in the firmware. I will go give that a try here this morning.
It is really strange to me that changing the software setting had an impact. Not the desired impact, of course. It basically rotated the same amount, but with different levels of vibration.
Then, when approaching it through the jumpers on the board, I wound up with noise and vibration from the motor, but the shaft didn't turn at all.
So, I've messed up in several ways. :) Now, I'm off to set the jumpers on the board and tweak the definition in the firmware. This is all an attempt to get to quarter stepping for my 135mm lens that was discussed in a separate thread previously.
OK, that firmware, configured for 1/4 steps, seems to be turning the shaft properly now. I'll have to wait for darker conditions to do any real testing.
I initially started to do that configuration with my existing firmware, but stepmode didn't exist in there. Is this something new coming with the 305 release?
Hi Scott
Congrats on progress.
When the firmware has a fixed stepmode - like the file I posted for you, the software will not stop you trying to send a different step mode.
But if you follow that with a get stepmode - it will always return the same. It is the firmware that prevents the stepmode change - like the application sends to the controller please change to stepmode 16 and the controller, when it gets that request says to istelf, hell no. I cannot do that so simply ignores the request for a step mode change.
Ah, gotcha. Makes sense. I'm gonna have a bit of a challenge no matter what though. I've got 3 different scopes and at least 2 different step modes required (I haven't been able to test out the SCT setup yet). Gonna be complicated if I have to upload firmware for every change.
I've gone on and ordered parts for the traditional, soldered unit. We'll see if I have the skills to pull it off. Who knows, maybe I'll just wind up with 3 controllers!
I have dedicated focus controllers for each scope. Saves time because they all have their own custom settings. And no mucking around trying to figure out why focus does not work.
For the cost of building a focuser its way cheaper than the time taken to try and trouble shoot issues.
Talking about controllers, counting all the beta and other controllers for testing that I have - think of a high number and start multiplying. After all, the code has to be tested on each different controller, so needless to say a large number.
It always pays to have a spare. I remeber driving two hours to a dark site, started setting up everything, only to find I had no counterweights for the mount.
Well, my PCBs arrived today. Other parts arriving by end of week. So, we'll see if I can get this figured out. :)
Fairly different question for you. When adjusting the pot on the driver board, would that setting be sensitive to the stepping mode? Testing the rig out tonight and the motor got super hot (in fact, warped my 3D printed carrier).
Testing the rig out tonight and the motor got super hot
What sort of motor are you running?
I prefer to adjust by hand and feel
https://www.dropbox.com/s/ks3cwabbg2cxcou/Stepper%20Motor%20Issues-01.mp4?dl=1
Set the correct step mode you will be using first.
I like also to send a long move to the stepper( with stepper on the bench) and try to stop the motor shaft - it after tuning I can easily stop the shaft from turning, then its not enough and I add a little more to the pot.
The difference between not working - working - over hot is very minute - probably no more than 10 degrees of rotation?
If the motor gets hot - either the current is too high or you are using a different NEMA motor with a higher coil rating or with a lower voltage rating the ones recommmended
If it is a geared motor, then it is ok to have coil power off. I really do not like recommended coil power off when using microstepping. I prefer to run all the focusers at full steps by working out the correct parameters first (step size and 10 steps in cfz).
Running in full step mode means plenty of torque, no need to have coil power on.
Regards
Robert
Hi Robert, I'm using the suggested NEMA14 motor on this rig. It is now set to run at 1/4 stepping.
I did follow the instructions for tuning the pot on the original setup which was driving the NEMA17-PG5 motor at half steps (although likely actually full steps given I had forgotten about the need to set the switches).
I have experimented with both coil power on and off with this rig. On certainly seems to be more consistent. I will attempt to tune the pot for this setup and see if I can get it dialed in.
I'll also be diving into building out more controllers soon. So, I'll tune each one specific to that rig.
Thanks again for the help!
Hi Scott
All adjustments should be done with Coil Power set ON
This is becase the stepper move routines needs to turn coil power ON in order to move the stepper motor. In brief, it looks something like this
If Coil Power is OFF this is how it moves
- if coil power = off
- - turn it on to move the motor
- - step the motor in the required direction
- - pause for 2us minimum (minimum required step pulse length
- - delay a period of time (insert a delay between step pulses) to ensure the motor does not exceed its rated rpm speed)
- - repeat while more steps to do
- end of move
- restore original Coil Power state. if it was off before, turn it OFF
regards
Robert