I have a 17HS3417 stepper motor. I want to use the example referred to but see a glaring problem with this. The current per phase of this motor, not sure what that means, is 1.7amps.
The example connects to digital pins 8,9,10,11. These pins cannot supply a current of 1.7 amps. I have a black,red,green,blue wire from the stepper.The example does not say which colour goes to which pin.
These wires to the stepper look like control wires, as in the wires to a servo motor which take negligible current.
Can anybody please explain what is missing in this example.There has to be something more to it to provide the necessary current.
You need a current controlling driver with these kind of motors, like the DRV8825, and an external power supply.
Do a search here in the forum, there is a lot of information.
The blue and red wire are connected to a 3 ohm coil and the green and black to another 3 ohm coil. Then for a digital output of 5v you need a current of 1.7 amps.
I have considered a driver but the driver just simply replaces the program already in the stepper library of arduino.
I will use a transistor connection to the coils and an external power supply of the appropriate current. The base of the transistor of course going to the digital outputs of my nano board.This should work for the given program without the large and cumbersome driver.
Perhaps the author of the stepper library was considering a very low power stepper where the digital outputs could support the current. Maybe there is such a type.
- Watch this complete Youtube video:
You should learn a little bit about steppers before going on. Steppers always need a driver, and which one depends on the type of steppers. Steppers cannot be connected to Arduino directly. As @MaximoEsfuerzo already pointed out, you need a current controlling driver and a suitable PSU to use this stepper. And your example ( which you didn't show ) is definitely not suitable for your needed stepper/driver combination. You only need two Arduino pins to use this stepper driver.
I wouldn't try that with this low impedance Stepper ...
You are right. I know very little about stepper motors. I am much more familiar with servo motors and have successfully used them with Arduino libraries for servos.
There is another driver which is A4988. DRV8825 has been mentioned.
Can I then program the driver from my nano board? Would the stepper example given in the Arduino IDE actually be for programming the driver and not directly the stepper?
I intend to use the stepper with the hollow rotating platform HRP60ke-g5-d5. The stepper fits neatly into this. It also has an input for a servo but I can't see what fitting would be required here.
These are very similar. But I would always prefer the DRV8825. It's the more modern driver, can provide a little bit more coil current and provides higher microstepping.
(1.7A is too much for the A4988, and the DRV8825 needs a heat sink)
You don't need to 'program' these drivers. They have a fixed functionality for such steppers. And there are some pins to influence the behaviour ( most importent are microstepping, coil current, enabling/disabling ). From the nano you usually only need to control the 'step' and 'dir' input, and maybe the 'enable' input to use the stepper.
As mentioned, there is no need for 'programming' the driver. you only need to create step pulses to get the stepper turning ( and set 'dir' accordingly to define the direction of turning.
But the stepper.h library is not suitable for this kind of stepper drivers. You can use my MobaTools library, or the widely used Accelstepper library. Both can be installed via the library manager.
When using Accelstepper you need non-blocking programming in the sketch to get the full functionality.
No it would not.
You need to use a stepper library such as Accelstepper. Install it using the library manager.
Thanks for that. A servo motor is also supposed to fit into the hollow rotating platform. The one recommended is 60mmX60mm standard servo. This would need an output shaft of 6mm diameter to fit into the rotating platform. Having difficulty finding one.
Here is the reason I would prefer a servo. It has only 3 wires. 2 are power and the other is a very low power control wire that can be run directly off the digital pins of the nano board.Then you don't need a driver at all. You use the library for a servo which is a really excellent library for controlling a servo.
If I cannot find a servo then I will need to use the stepper. Thank you for all your advice on this and to use the DRV8825 rather than the A4988.
Maybe somebody on this forum could find me a suitable servo for the hollow rotating platform. I have come across a few that don't use the 3 wires that the servos I use have and make it so simple to control a servo.
Be aware, that there is a big difference between a hobby servo which are mostly used in model airplanes or small hobby robots, and a real servo motor which is mostly used in industrial equipment.
Despite the fact, that both have 'servo' in their name, they are very different devices, that are also controlled very differently.
Your hollow rotating platform needs a servo motor ( or a stepper), but not a (hobby) servo.
Do you need something reliable that will operate over a wide ambient temperature range?
Got it. My hollow rotating platform is HRP60KE-G5-D5. No operating instructions from the Chinese manufacturer except any standard servo 60x60mm servo will fit.
But as you say this would have to be an industrial servo not a hobby servo. Any suggestions as to what this may be.The stepper I have has a 8mm shaft fitting into a 8mm socket on the platform. The servo would need the same diameter shaft. I can see it fits where the stepper fits. There is no other input for the servo.
I suppose I need a driver for the servo then? Can't see from the picture you sent how many wires fit into the unit at the top. I guess not the simple low power controlling wire and 2 power wires of my hobby servo?
Is it this one? There is a lot of technical data. But its different from what you write.
Usually these servos are sold with a suitable driver, as in the link @jim-p provided. But I think these servos are too big for your mechanics.
The logic interface to the Arduino is described in the datasheet of the driver (CAN-bus in the linked controller). You cannot see that from the number of wires only.
See post #13
That is correct. See post #13
You may also consider reading post #14
Is this the only reason you want to replace your existing stepper with a servo motor? As you know now, you will not find a servo motor that fits to your gear-box and is controlled that way. There are servos with integrated driver which are controlled the same way as a stepper. Because the driver is integrated, you can connect them directly to Arduino pins. But from the Arduino point of view ( programming ) it's identical to a stepper. So, do you still want to switch to servo motor?