My usual stepper controller is the Sparkfun Big Easy Driver, however lately I have been looking for something capable of driving a bigger stepper motor. Then I found this TB6600 Single Axis 4A Stepper Motor Driver Controller 9~40V Micro-Step CNC EBUK Not quite a Remmington moment but I did buy 2 of them at approx £6.50 each with free p&p. When they arrive I will try connecting it to a Nema 17 and a Nema 23 stepper motor, controlled by the Arduino. Paul
The sparkfun Big Easy Driver can only support up to 2A, so limits the size of motor that can be controlled, this will allow larger motors. Looking at the picture, at the top edge of the controller can be seen a label for dip switches on the top edge (SW1 to SW6). S1 to S3 are used to setup micro-stepping S4 to S6 are used to set the current limits. And for £6.50 worth a punt to test. Paul
Just as a taster, I found this Youtube video. The A4988 (smaller stepper driver) is the same chip as the Big Easy driver uses. Paul
They arrived today - 7 days from China on free postage, that'll put some next day delivery to shame. And the dip switches to configure the device A nice contained unit, the connectors are two blocks of 6 pin plugs. The plugs lock into place and wont shake loose. Top plug on photo marked Signal has the control signal inputs to the driver ENA Enable DIR Direction PUL Pulse signal The + & - for each input allow you to use controllers with either comm anode (+) or cathode (- or ground), and even use different controllers for each input. For an arduino the usual setting would be to connect the - to the Arduino Gnd connector. The lower plug marked High Voltage has the power input and Stepper coil outputs. Paul
Would something like this also help with the turn table? Saving the stop switch? I’d love to do a stepper motor turntable as we discussed in the past, but I just didn’t like the issue of having the stop point and not be able to do a 720 rotate.
The sample sketch had a limit switch that was in the path of the turntable (easy option for the demo), if you move the switch to the side so that the turntable can rotate past the switch without fouling, maybe with a chamfer each side of the flag The limit switch is only used to set the zero position of the turntable, all movements are relative to the zero point. The above would give full 360 degree operation, with the turntable having an A & B end and would rotate in either direction to align with the entry / exit point required. As I use Nema 17 motors (nominal 1 to 2 A) for the traversers, either the Big Easy Driver, a Generic A4988 3D printer driver (same chipset as the Big Easy Driver) or this TB6600 Driver would work. If the turntable only had 1 entry / exit road, then it could be easily set up, to just rotate 180 degrees each time a button was pressed. Paul
I wonder (subject to how much one may cost) if some kind of optical sensor like Heathcotes use on their IRDOT signalling could be used as the home point? Could be hidden as the square locks in the wall as per a real TT.. and the other half in the deck. There again, a second disc under the deck could be positioned with a lobe to trigger a roller contact switch.
As long as the detector reliably hits the same spot everytime to establish the zero position, you can use any form of switch. Viccy Roads traverser doesn't use a zero routine, instead the trac is manually aligned with the entry road before switching on. The zero position is then set during the Startup routine. Paul
Rather than a micro switch and a cam lobe, you could use an extended pin, that passes through a "through beam slot" photo electric sensor.
You could also embed a neodymium magnet in the turntable deck and place a hall effect transistor in the wall of the pit to detect the magnet. The steps would be 1. Rotate turntable anticlockwise until the halleffect transistor changes state at normal speed 2. Stop turtable 3. Rotate turntable clockwise enough steps to clear the magnet. 4. Set speed to very slow (single steps) 5. Rotate turntable anticlockwise 1 step - hall effect transistor detected magnet, if not repeat 6. Hall effect transistor changes state - Stop rotation 7. Set current position to 0 (zero) 8. Set speed to normal 9. Rotate to entry position Simples Paul
Hi Andy The best method of registration switches I have found yet are the hall switches like this https://uk.rs-online.com/web/p/hall-effect-sensors/8223778/ or one on a board like this https://www.dccinterface.com/product/hall-effect-magnetic-sensor-module/ all you need to do then is arrange a magnet to pass by the sensor. If you need more help let me know. Paul I hope you dont mind me sticking my nose in here. be seeing you Bob
