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Forum Index : Microcontroller and PC projects : Stepper Motors
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palcal Guru  Joined: 12/10/2011 Location: AustraliaPosts: 1873 |
Hi All, Having my first attempt at stepper motors, I have one of These I searched for information and came up with some code from 2011. I modified it a bit to get rid of the line numbers. This is the code. DIM A$(3) SETPIN 15,DOUT SETPIN 16,DOUT SETPIN 17,DOUT SETPIN 18,DOUT DATA "0110","0101","1001","1010" FOR X=0 TO 3 READ A$(X) NEXT X DO FOR STP=0 TO 3 'CW rotation FOR Y=0 TO 3 PIN(Y+1)=VAL(MID$(A$(STP),Y+1,1)) NEXT Y PAUSE 5 'increase PAUSE value to SLOW rotation. NEXT STP Pause 50 FOR STP=3 TO 0 STEP -1 'CCW rotation FOR Y=0 TO 3 PIN(Y+1)=VAL(MID$(A$(STP),Y+1,1)) NEXT Y PAUSE 5 'increase PAUSE value to SLOW rotation. NEXT STP LOOP I haven't tried it yet as I suspect there is a better way of doing it. I was thinking maybe the PORT command could be used to set the pins. I have a fair idea of how the motor works energising the coils in turn but haven't quite got it clear in my head yet. I don't understand how it can have 4096 steps per revolution. The object of my project is to get the motor to oscillate 1/2 a turn slowly back and forth say a 2 or 3 second cycle. Any suggestions. Edited 2023-07-27 18:05 by palcal "It is better to be ignorant and ask a stupid question than to be plain Stupid and not ask at all" |
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Mixtel90 Guru Joined: 05/10/2019 Location: United KingdomPosts: 6798 |
You could use PORT(GP15,4)=n for example, but I'd use the decimal values for n rather than convert them on every output command. It's easier. Mick Zilog Inside! nascom.info for Nascom & Gemini Preliminary MMBasic docs & my PCB designs |
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| Volhout Guru Joined: 05/03/2018 Location: NetherlandsPosts: 4247 |
Hi Pascal, Your code uses an ASCII (text) pattern that is convertoed to logic bits at each step of the motor. That is consuming CPU, so it will slow down the motor maximum speed. As mick said: store the bit pattern as a nibble (4 bits) in an integer array. dim pattern%(3)=(&b0110,&b0101,&b1001,&b1010) And then FOR STP=0 TO 3 'CW rotation PORT(GP15,4)=pattern%(STP) PAUSE 5 'increase PAUSE value to SLOW rotation. NEXT STP You ask about many steps per rotation: the position of the rotor axis is depending on the position of the rotor between the magnetic poles. When you drive the poles ON/OFF then you have only few steps. But if you drive them 100%/50%/0% you get more steps. And if you increase this to 100%/80%/60%/40%/20%/0, you can imagine there are many more rotor positions possible. They call these steps "microsteps". And a smart control of each pole pair can guarantee constant torque in each of these "micro-positions". i.e. you get the same rotor position when 1 coils is 20% the other is 40%, as when 30%/60% or 40%/80% or 50%/100%. But in each of these cases, the torque that the motor can deliver is different. In many modern stepper driver the current through the coil is controlled from a PWM system with feedback (measuring the actual current). Edited 2023-07-27 20:43 by Volhout PicomiteVGA PETSCII ROBOTS |
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Martin H. Guru Joined: 04/06/2022 Location: GermanyPosts: 1114 |
Dont you need some of those stepper-motor-drivers like they are used an Arduino Boards for 3d Printers? 'no comment |
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| Volhout Guru Joined: 05/03/2018 Location: NetherlandsPosts: 4247 |
Pascal has stepper motors that have centre tapped coils (6 wires, 3 for each coil). The centre pins go to +5V, you connect the other 2 alternating to ground. His "driver"is a ULN2003 that can do this. The ULN2003 has no intelligence. So his software has to do everything. Drive each individual pin (generate the phase rotation signals), control the frequency of that rotation. Most of that is done in hardware in more modern chips. Volhout P.S. Pascal, your motors have something like 64 steps per rotation, but have a gear box attached. That is why on the outgoing axis it may look like 4000 steps per rotation. Edited 2023-07-27 23:09 by Volhout PicomiteVGA PETSCII ROBOTS |
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Rickard5 Guru Joined: 31/03/2022 Location: United StatesPosts: 463 |
Hi Pacal What stepper Drivers are you using? My Big Dream is to use StepStick A4988/DRV8825 Stepper Motor Drivers Mainly because their Cheep, Plentiful, and I have a Bazillion of those drivers and matching Steppers from the pond of 3D printers that have run though my world and have been since parted out for salvage I may be Vulgar, but , while I'm poor, I'm Industrious, Honest, and trustworthy! I Know my Place |
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| Martin H. Guru Joined: 04/06/2022 Location: GermanyPosts: 1114 |
Thank you, the stepper Motors I use are Nema17 (or clones): I asked, cause i swapped the Stepeprdrivers in my Printers to TRINAMIC (TMC) so I have a bunch of those "normal" Drivers laying arround. 'no comment |
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stanleyella Guru Joined: 25/06/2022 Location: United KingdomPosts: 2129 |
I must convert this to mmbasic from gcbasic. It sends a byte or port ie 4 poles to 2 motors. real 8 bit...and the sh..erry .looks like these but narrower gear box https://www.youtube.com/watch?v=s5-5DNa36jk ;------------------- sub motors ;left motor if l_mot_dir<>stop then if l_mot_dir=forward then l_mot_pos++ if l_mot_pos=5 then l_mot_pos=1 else l_mot_pos--- if l_mot_pos=0 then l_mot_pos=4 end if readtable l_mot_phase,l_mot_pos,l_mot_port else l_mot_port=0b11110000 end if ;right motor if r_mot_dir<>stop then if r_mot_dir=forward then r_mot_pos++ if r_mot_pos=5 then r_mot_pos=1 else r_mot_pos--- if r_mot_pos=0 then r_mot_pos=4 end if readtable r_mot_phase,r_mot_pos,r_mot_port else r_mot_port=0b00001111 end if ;out left right phase to port portd=l_mot_port and r_mot_port end sub ; table l_mot_phase 0b11110011,0b11110110,0b11111100,0b11111001 end table table r_mot_phase 0b00111111,0b01101111,0b11001111,0b10011111 end table Edited 2023-07-28 04:28 by stanleyella |
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| Mixtel90 Guru Joined: 05/10/2019 Location: United KingdomPosts: 6798 |
Erm.... he's using the ones shown in his link. :) These are sometimes supplied with the 25/30/35/40/45 or whatever Arduino experimenter kits. You get the motor and the driver. They are Chinese, cheap and the only reason they will pull the skin off a (small) rice pudding is because they are geared down. Edited 2023-07-28 04:18 by Mixtel90 Mick Zilog Inside! nascom.info for Nascom & Gemini Preliminary MMBasic docs & my PCB designs |
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| circuit Senior Member  Joined: 10/01/2016 Location: United KingdomPosts: 245 |
There are two main types of stepper motor; unipolar and bipolar. In the case of unipolar motors the drive coils are powered in sequence to turn the rotor. These motors may allow access to the four individual coils, but the motor in question has FIVE wires and therefore can only be wired as a unipolar motor. Bipolar motors normally have four wires and require polarity reversal between pulses to operate. This requires more complex H-Bridge drivers. The advantage of unipolar motors is simplicity of the driver circuit; all that you need to do is to pulse the coils in sequence. As highlighted in previous posts, the motor is quite highly geared and therefore half-step or micro-stepping is virtually irrelevant to the operation of this motor, though admittedly half-stepping may make the operation a little smoother. As stepper motors go, the 28BYJ-48 motor which you have is not a good representative of what a stepper motor can do because there is usually quite a lot of play in the gearbox. The normal advantage of a stepper motor is accuracy and reproducibility of angular alignment, something rather missing in the 28BYJ-48 motors. Be aware that it has been reported (and well-illustrated) that the gearboxes vary quite a lot between models, even though they all have the same 28BYJ-48 designation. This also means that you cannot rely upon the 'steps per revolution' figure on many of these motors. The variability in gearboxes means that the amount of slop in the final drive ranges from a minor nuisance across to downright wobbly. Although Mick implied they lack power, the torque multiplication through the gearbox means that if you try and hold the final drive shaft there is enough torque to rip the teeth right off the gears. Obviously, the high ratio reduction means that they are inevitably very slow in operation. All said, you have a very cheap entry into the technology of steppers and these should provide a useful exercise to learn how the things work - and there is plenty of information on your motor out there on the net; just look up '28BYJ-48' Finally, Volhout's programme snippit is a most elegant way to drive the motor. Edited 2023-07-28 05:25 by circuit |
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| circuit Senior Member Joined: 10/01/2016 Location: United KingdomPosts: 245 |
This is a most useful source of information from Texas Instruments on stepper motors; TI guide to stepper motors |
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| stanleyella Guru Joined: 25/06/2022 Location: United KingdomPosts: 2129 |
I was assuming not real stepper motor. Real ones need a big psu and driver. a 3d printer is a good example, mine's using a 328p to do it all...and a driver. There's lots of info about 4 phase steppers and phasing signals, These cheap geared things come with driver (leds un turn offable) board. https://lastminuteengineers.com/28byj48-stepper-motor-arduino-tutorial/ |
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Hans Senior Member Joined: 18/10/2022 Location: CanadaPosts: 116 |
Hi Palcal I use this type of stepper on my N scale train turntable. I have supplied code for it, but it is not optimized and not the final code that I will use as I was simply using it to test the turntable. The final code will be modified to run on a Pico W instead of the Pico that I use now. BTW, this code works with Ver 5.07.07 , enjoy!   ' Stepper20 Driver ' 28BYJ-48 Stepper Motor SetPin gp0, dout SetPin gp1, dout SetPin gp2, dout SetPin gp3, dout Position% = 0 StepCounter% = 1 Speed% = 20 if mm.info(device) = "WebMite" Then WEB NTP -4 EndIf Again: 'For Cur% = 1 To 26 'Next Cur% Print "(F)orward, (B)ackward, (C)ontinus, (S)peed, (Q)uit" Input key$ If key$ = "F" Or key$ = "f" Then fmotion stepcounter% = 0 Stepper GoTo Again EndIf If key$ = "B" Or key$ = "b" Then 'Stepper runs counter clock wise bmotion stepcounter% = 0 Stepper GoTo Again EndIf AskThis: If key$ = "C" Or key$ = "c" Then 'Single Step Print "(F)oward, (B)ack" Input key$ If key$ = "F" Or key$ = "f" Then fmotion If key$ = "B" Or key$ = "b" Then bmotion If key$ = "B" Or key$ = "b" Or key$ = "F" Or key$ = "f" Then Print "Enter a stop point" Input StopPoint% Continus Else Print key$;"- was not a choise" GoTo Again EndIf EndIf If key$ = "S" Or key$ = "s" Then 'Change speed OldSpeed% = Speed% Print "Enter Speed 1 to 20, 1 is fastest" Input Speed% If Speed% < 1 Or Speed% > 20 Then Print "Incorrect speed try again" Speed% = OldSpeed% GoTo Again EndIf EndIf If key$ = "Q" Or key$ = "q" Then 'End the program End EndIf GoTo Again Sub Stepper '32 micro steps is one full rotation For Position% = 0 To 32 '15 * 8 is 1 micro step For Counter% = 0 To 15 State$ = step1$ Pin(gp0) = Val(Mid$(State$,1,1)) Pin(gp1) = Val(Mid$(State$,2,1)) Pin(gp2) = Val(Mid$(State$,3,1)) Pin(gp3) = Val(Mid$(State$,4,1)) Pause Speed% State$ = step2$ Pin(gp0) = Val(Mid$(State$,1,1)) Pin(gp1) = Val(Mid$(State$,2,1)) Pin(gp2) = Val(Mid$(State$,3,1)) Pin(gp3) = Val(Mid$(State$,4,1)) Pause Speed% State$ = step3$ Pin(gp0) = Val(Mid$(State$,1,1)) Pin(gp1) = Val(Mid$(State$,2,1)) Pin(gp2) = Val(Mid$(State$,3,1)) Pin(gp3) = Val(Mid$(State$,4,1)) Pause Speed% State$ = step4$ Pin(gp0) = Val(Mid$(State$,1,1)) Pin(gp1) = Val(Mid$(State$,2,1)) Pin(gp2) = Val(Mid$(State$,3,1)) Pin(gp3) = Val(Mid$(State$,4,1)) Pause Speed% State$ = step5$ Pin(gp0) = Val(Mid$(State$,1,1)) Pin(gp1) = Val(Mid$(State$,2,1)) Pin(gp2) = Val(Mid$(State$,3,1)) Pin(gp3) = Val(Mid$(State$,4,1)) Pause Speed% State$ = step6$ Pin(gp0) = Val(Mid$(State$,1,1)) Pin(gp1) = Val(Mid$(State$,2,1)) Pin(gp2) = Val(Mid$(State$,3,1)) Pin(gp3) = Val(Mid$(State$,4,1)) Pause Speed% State$ = step7$ Pin(gp0) = Val(Mid$(State$,1,1)) Pin(gp1) = Val(Mid$(State$,2,1)) Pin(gp2) = Val(Mid$(State$,3,1)) Pin(gp3) = Val(Mid$(State$,4,1)) Pause Speed% State$ = step8$ Pin(gp0) = Val(Mid$(State$,1,1)) Pin(gp1) = Val(Mid$(State$,2,1)) Pin(gp2) = Val(Mid$(State$,3,1)) Pin(gp3) = Val(Mid$(State$,4,1)) Pause Speed% Next Counter% Print StepCounter%;" "; StepCounter% = StepCounter% + 1 Next Position% End Sub Sub Continus StepCounter% = 0 Do State$ = step1$ Pin(gp0) = Val(Mid$(State$,1,1)) Pin(gp1) = Val(Mid$(State$,2,1)) Pin(gp2) = Val(Mid$(State$,3,1)) Pin(gp3) = Val(Mid$(State$,4,1)) Pause Speed% State$ = step2$ Pin(gp0) = Val(Mid$(State$,1,1)) Pin(gp1) = Val(Mid$(State$,2,1)) Pin(gp2) = Val(Mid$(State$,3,1)) Pin(gp3) = Val(Mid$(State$,4,1)) Pause Speed% State$ = step3$ Pin(gp0) = Val(Mid$(State$,1,1)) Pin(gp1) = Val(Mid$(State$,2,1)) Pin(gp2) = Val(Mid$(State$,3,1)) Pin(gp3) = Val(Mid$(State$,4,1)) Pause Speed% State$ = step4$ Pin(gp0) = Val(Mid$(State$,1,1)) Pin(gp1) = Val(Mid$(State$,2,1)) Pin(gp2) = Val(Mid$(State$,3,1)) Pin(gp3) = Val(Mid$(State$,4,1)) Pause Speed% State$ = step5$ Pin(gp0) = Val(Mid$(State$,1,1)) Pin(gp1) = Val(Mid$(State$,2,1)) Pin(gp2) = Val(Mid$(State$,3,1)) Pin(gp3) = Val(Mid$(State$,4,1)) Pause Speed% State$ = step6$ Pin(gp0) = Val(Mid$(State$,1,1)) Pin(gp1) = Val(Mid$(State$,2,1)) Pin(gp2) = Val(Mid$(State$,3,1)) Pin(gp3) = Val(Mid$(State$,4,1)) Pause Speed% State$ = step7$ Pin(gp0) = Val(Mid$(State$,1,1)) Pin(gp1) = Val(Mid$(State$,2,1)) Pin(gp2) = Val(Mid$(State$,3,1)) Pin(gp3) = Val(Mid$(State$,4,1)) Pause Speed% State$ = step8$ Pin(gp0) = Val(Mid$(State$,1,1)) Pin(gp1) = Val(Mid$(State$,2,1)) Pin(gp2) = Val(Mid$(State$,3,1)) Pin(gp3) = Val(Mid$(State$,4,1)) Pause Speed% Print StepCounter%;" "; StepCounter% = StepCounter% + 1 If StepCounter% = StopPoint% Then Exit Sub Loop End Sub Sub fmotion step1$ ="1000" step2$ ="1100" step3$ ="0100" step4$ ="0110" step5$ ="0010" step6$ ="0011" step7$ ="0001" step8$ ="1001" End Sub Sub bmotion step8$ ="0111" step7$ ="0011" step6$ ="1011" step5$ ="1001" step4$ ="1101" step3$ ="1100" step2$ ="1110" step1$ ="0110" End Sub Hans ...  PS: I do use an ULN2003 driver board with it (as your link shows) and power it with a separate 5 volt supply to the board. Edited 2023-07-28 06:03 by Hans |
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vegipete Guru Joined: 29/01/2013 Location: CanadaPosts: 1109 |
A number of those bit patterns have 3 bits set. Are you sure that is what you want? Visit Vegipete's *Mite Library for cool programs. |
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| Hans Senior Member Joined: 18/10/2022 Location: CanadaPosts: 116 |
I don't pretend to know how this works entirely, however it is what I gleaned from this web site when I was researching the 28BYJ-48; 28BYJ-48 Please correct me if I have not understood the concept.  I really am a noob when it comes to integration of electronics and code. I have seen a lot of smart code and designs on this site from you guys. Everyday I come to this site I learn something new. Hans ... |
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| DaveJacko Regular Member  Joined: 25/07/2019 Location: United KingdomPosts: 76 |
I've done a couple of projects using steppers and a Micromite. You might like to watch these short videos; https://youtu.be/I-1TruQKnw8 https://youtu.be/Buybf25-wbg turn up your volume on the x-y plotter video, and listen to the music of the steppers! I think that with a little creativity, the Mite or Pico could run many more than the 2 axes and faster than 1kHz that I have achieved here. Ramping is not used here though. I can post the code if anyone wants. |
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| Hans Senior Member Joined: 18/10/2022 Location: CanadaPosts: 116 |
Hi Dave; I would never say no to extra code! I see the steppers you are using are the typical type that are used on 3D printers? I showed the water gadget to my wife and I think I have another project now.  Never thought to use a driver board from Arduino, what board is that exactly? Thanks for the post Dave Hans ... |
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| palcal Guru Joined: 12/10/2011 Location: AustraliaPosts: 1873 |
Thanks for all the help, I understand a lot more now. I have some code that I think will work so I will connect up the hardware and see how it goes. I might be a bit eccentric but I am building a winder to keep my automatic watch wound while I am not wearing it. The watch can't be wound using the crown and relies on movement. I was amazed but they are actually commercially available. See HERE "It is better to be ignorant and ask a stupid question than to be plain Stupid and not ask at all" |
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| Volhout Guru Joined: 05/03/2018 Location: NetherlandsPosts: 4247 |
For this motor patterns with both coils in one direction active will only heat up the motor. Volhout PicomiteVGA PETSCII ROBOTS |
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| Hans Senior Member Joined: 18/10/2022 Location: CanadaPosts: 116 |
@volhout, @Vegipete Thanks, now I understand what you guys were getting at. Yes I was wondering why the stepper was running warm but it's not hot. I thought it was normal running not having driven one of these before. My mistake from the web site was I assumed the 1's in the chart represented an on state. My new code uses; Sub bmotion step8$ ="1000" step7$ ="1100" step6$ ="0100" step5$ ="0110" step4$ ="0010" step3$ ="0011" step2$ ="0001" step1$ ="1001" End Sub Thanks guys it runs perfectly cool now! In the code that palcal has shown, there are only 4 sets of digital values, should I be using that to run the stepper correctly? Hans ... |
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