Hello all!
I just finished my focuser controller and everything seems to work ok, except the.... motor!
A few details first, my version is a drv8825-oled-rotary encoder and everything works fine, the leds, the buzzer, the temperature probe, even the windows application indicates that the focuser is moving when i issue a command.
I double checked most of the connections and there isn't an obvious problem.
The problem is with the motor, there is no current flowing through the coils, i cannot get it to work neither with the encoder, nor with the app.
When i change "coil power" from "off" to "on" my multimeter shows zero current.
I measured the voltage between the rs 232's pins, i get 0.2v reading between the coils, i don't know if this means something...
My motor is a NEMA14 purchased directly from stepper online.
I don't know if there is something obvious i'm missing but i've run out of ideas...
update
I just measured the coils' resistance @25Ω which is inside the specs, so this rules out a motor problem.
update2
The only hardware change i have made is to wire one 330Ω resistor in series with the in-out leds and a 40kΩ one to the red power led to dim it, i don't think it plays a role but i should have mentioned it.
Last edit: Stamatis Paraschakis 2018-02-19
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Last check is the ENable pin on the DRV8825.
It should be LOW or GND when moving, HIGH or 5V when stopped.
What is the voltage on the ENABLE pin when stopped and then when moving?
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Measure between EN and GND - we are looking for around 0V when moving, 5V when not.
Tracing back EN - which arduino nano pin is it wired to?
You built a stripboard?
If EN is high when moving (it might fluctuate a little - do a long move from say 9000 to 0 when measuring, then that indicates the DRV8825 is dead.
And what firmware are you using?
Focuserv266_DRV8825_RE
try the
Focuserv266_DRV8825
also, just disable the display/RE/probe and test using only LEDS and BUZZER
Last edit: brownrb 2018-02-19
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Well, problem found...
I put the drv the other way around... Very very, very silly... I wonder where was my mind ...
Is the drv now fried?
I've also noticed that i cannot upload a new firmware to the nano, i get the following error.
Sketch uses 15,596 bytes (50%) of program storage space. Maximum is 30,720 bytes.
Global variables use 530 bytes (25%) of dynamic memory, leaving 1,518 bytes for local variables. Maximum is 2,048 bytes.
avrdude: stk500_recv(): programmer is not responding
avrdude: stk500_getsync() attempt 1 of 10: not in sync: resp=0xe5
avrdude: stk500_recv(): programmer is not responding
avrdude: stk500_getsync() attempt 2 of 10: not in sync: resp=0xe5
avrdude: stk500_recv(): programmer is not responding
avrdude: stk500_getsync() attempt 3 of 10: not in sync: resp=0xe5
avrdude: stk500_recv(): programmer is not responding
avrdude: stk500_getsync() attempt 4 of 10: not in sync: resp=0xe5
avrdude: stk500_recv(): programmer is not responding
avrdude: stk500_getsync() attempt 5 of 10: not in sync: resp=0xe5
avrdude: stk500_recv(): programmer is not responding
avrdude: stk500_getsync() attempt 6 of 10: not in sync: resp=0xe5
avrdude: stk500_recv(): programmer is not responding
avrdude: stk500_getsync() attempt 7 of 10: not in sync: resp=0xe5
avrdude: stk500_recv(): programmer is not responding
avrdude: stk500_getsync() attempt 8 of 10: not in sync: resp=0xe5
avrdude: stk500_recv(): programmer is not responding
avrdude: stk500_getsync() attempt 9 of 10: not in sync: resp=0xe5
avrdude: stk500_recv(): programmer is not responding
avrdude: stk500_getsync() attempt 10 of 10: not in sync: resp=0xe5
Problem uploading to board. See http://www.arduino.cc/en/Guide/Troubleshooting#upload for suggestions.
It connects to the app fine though and yesterday i could upload an updated firmware.
So, so embarrased...
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I have finally finished the controller! Of course the old nano is bricked as Robert said...
Fortunately i have 3 spare pcbs so i decided to make a new one instead of trying to desolder the nano and the drv.
I have a couple of questions though.
When the "coil power" is on and the focuser is not moving a can hear a frying noise coming from the motor. Is that normal? It also gets hot enough to puzzle me. (I have adjusted the pot to get a 0.240A current reading).
PS. When i made the first test and clicked the +1 or -1 buttons the motor moved pretty undpredictable .
I then issued 2-3 commands to move 7000-8000 steps and everything seems to work fine now.
If you would like to refer to this comment somewhere else in this project, copy and paste the following link:
Hi Stamatis
I think the best way to set the drv8825 is by manual method - the video does this.
A frying noise is the chopping to keep the position, I assume you are micro-stepping the motor, winding down the current a bit should help. It shouldnt get hot. Warm ok, but not hot. Mine run fairly cold (room temp?). If the motor moved pretty unpredictable it is most likely the current setting.
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Hi Robert
I did set the current the way you suggested and now the heat, noise and vibrations are significantly minimized.
The sweet spot for my NEMA14 is around 0.15-0.16a (interestingly there is a region around 0.2a where the motor behaves strangely, it changes direction, vibrates, stalls etc).
Do you think a bipolar modded 28byj-48 (http://www.electronicsmayhem.com/?p=13) would work for low torque purposes, for example a camera lens?
Last edit: Stamatis Paraschakis 2018-02-27
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Hi Stamatis
I don't like the 28byj motors - I prefer the NEMA motors, you could look at a smaller Nema8 or 11 motor? There are even geared models in this size, and current at 0.6A is still ok.
With a GT2 6mm belt and pulley on the stepper, you have a great amount of reduction and can easily use full stepping. With full stepping/gearing you can operate with coil power off.
However, that does not mean that say that a BY modded motor would not work.
If you would like to refer to this comment somewhere else in this project, copy and paste the following link:
Hello all!
I just finished my focuser controller and everything seems to work ok, except the.... motor!
A few details first, my version is a drv8825-oled-rotary encoder and everything works fine, the leds, the buzzer, the temperature probe, even the windows application indicates that the focuser is moving when i issue a command.
I double checked most of the connections and there isn't an obvious problem.
The problem is with the motor, there is no current flowing through the coils, i cannot get it to work neither with the encoder, nor with the app.
When i change "coil power" from "off" to "on" my multimeter shows zero current.
I measured the voltage between the rs 232's pins, i get 0.2v reading between the coils, i don't know if this means something...
My motor is a NEMA14 purchased directly from stepper online.
I don't know if there is something obvious i'm missing but i've run out of ideas...
update
I just measured the coils' resistance @25Ω which is inside the specs, so this rules out a motor problem.
update2
The only hardware change i have made is to wire one 330Ω resistor in series with the in-out leds and a 40kΩ one to the red power led to dim it, i don't think it plays a role but i should have mentioned it.
Last edit: Stamatis Paraschakis 2018-02-19
Check that you have 12V external supply. Motor will not turn without 12V
Check that 12V is going to the DRV8825 chip - measure between the VMOT and ground
Have you adjusted the little pot for current? Set it mid-point to start
Did you put the capacitor across VMOT and GND close to the DRV8825 chip?
Let me know result of your tests
Yes to everything Robert, except the pot adjusting part, i get no current reading no matter how much i turn the pot...
Last check is the ENable pin on the DRV8825.
It should be LOW or GND when moving, HIGH or 5V when stopped.
What is the voltage on the ENABLE pin when stopped and then when moving?
Measure between EN and GND - we are looking for around 0V when moving, 5V when not.
Tracing back EN - which arduino nano pin is it wired to?
You built a stripboard?
If EN is high when moving (it might fluctuate a little - do a long move from say 9000 to 0 when measuring, then that indicates the DRV8825 is dead.
And what firmware are you using?
Focuserv266_DRV8825_RE
try the
Focuserv266_DRV8825
also, just disable the display/RE/probe and test using only LEDS and BUZZER
Last edit: brownrb 2018-02-19
Well, problem found...
I put the drv the other way around... Very very, very silly... I wonder where was my mind ...
Is the drv now fried?
I've also noticed that i cannot upload a new firmware to the nano, i get the following error.
Sketch uses 15,596 bytes (50%) of program storage space. Maximum is 30,720 bytes.
Global variables use 530 bytes (25%) of dynamic memory, leaving 1,518 bytes for local variables. Maximum is 2,048 bytes.
avrdude: stk500_recv(): programmer is not responding
avrdude: stk500_getsync() attempt 1 of 10: not in sync: resp=0xe5
avrdude: stk500_recv(): programmer is not responding
avrdude: stk500_getsync() attempt 2 of 10: not in sync: resp=0xe5
avrdude: stk500_recv(): programmer is not responding
avrdude: stk500_getsync() attempt 3 of 10: not in sync: resp=0xe5
avrdude: stk500_recv(): programmer is not responding
avrdude: stk500_getsync() attempt 4 of 10: not in sync: resp=0xe5
avrdude: stk500_recv(): programmer is not responding
avrdude: stk500_getsync() attempt 5 of 10: not in sync: resp=0xe5
avrdude: stk500_recv(): programmer is not responding
avrdude: stk500_getsync() attempt 6 of 10: not in sync: resp=0xe5
avrdude: stk500_recv(): programmer is not responding
avrdude: stk500_getsync() attempt 7 of 10: not in sync: resp=0xe5
avrdude: stk500_recv(): programmer is not responding
avrdude: stk500_getsync() attempt 8 of 10: not in sync: resp=0xe5
avrdude: stk500_recv(): programmer is not responding
avrdude: stk500_getsync() attempt 9 of 10: not in sync: resp=0xe5
avrdude: stk500_recv(): programmer is not responding
avrdude: stk500_getsync() attempt 10 of 10: not in sync: resp=0xe5
Problem uploading to board. See http://www.arduino.cc/en/Guide/Troubleshooting#upload for suggestions.
It connects to the app fine though and yesterday i could upload an updated firmware.
So, so embarrased...
probably fried. They are very easy to blowup
Check in Arduino Menu - Tools-Board = "Arduino Nano" and Tools-Programmer = "AVRISP mkii"
Did you have power on reset circuit fitted - if so if must be disabled to upload new firmware
If all is as per above then Nano is probably bricked.
I have finally finished the controller! Of course the old nano is bricked as Robert said...
Fortunately i have 3 spare pcbs so i decided to make a new one instead of trying to desolder the nano and the drv.
I have a couple of questions though.
When the "coil power" is on and the focuser is not moving a can hear a frying noise coming from the motor. Is that normal? It also gets hot enough to puzzle me. (I have adjusted the pot to get a 0.240A current reading).
PS. When i made the first test and clicked the +1 or -1 buttons the motor moved pretty undpredictable .
I then issued 2-3 commands to move 7000-8000 steps and everything seems to work fine now.
Hi Stamatis
I think the best way to set the drv8825 is by manual method - the video does this.
A frying noise is the chopping to keep the position, I assume you are micro-stepping the motor, winding down the current a bit should help. It shouldnt get hot. Warm ok, but not hot. Mine run fairly cold (room temp?). If the motor moved pretty unpredictable it is most likely the current setting.
Hi Robert
I did set the current the way you suggested and now the heat, noise and vibrations are significantly minimized.
The sweet spot for my NEMA14 is around 0.15-0.16a (interestingly there is a region around 0.2a where the motor behaves strangely, it changes direction, vibrates, stalls etc).
Do you think a bipolar modded 28byj-48 (http://www.electronicsmayhem.com/?p=13) would work for low torque purposes, for example a camera lens?
Last edit: Stamatis Paraschakis 2018-02-27
Hi Stamatis
I don't like the 28byj motors - I prefer the NEMA motors, you could look at a smaller Nema8 or 11 motor? There are even geared models in this size, and current at 0.6A is still ok.
With a GT2 6mm belt and pulley on the stepper, you have a great amount of reduction and can easily use full stepping. With full stepping/gearing you can operate with coil power off.
However, that does not mean that say that a BY modded motor would not work.