Stepper motor wiring help(and a few other small questions from an instructable)

Here is an excelent resource regarding steppers and how they work

http://www.geckodrive.com/support.html

I found this to be very helpfull in setting up my CNC project

your stepper is a classic 4 wire / 2 coil 7.5deg per step so 360/7.5 = 48 full steps per revolution

also it looks like the black and orange are one coil and the brown/yellow the other

if you want to reverse the direction in hardware then simply swap the connection of black and orange (Put the black where the orange was and the orange where the black was) or do the similar thing with the other coil wires

Hope this helps, if you need more info then just ask

I ordered the  SN754410NESN754410NE to use for my project and i just had a few questions about wiring it up the diagram you gave was very helpful but why do i need to hook up my arduino 5v to 1,2 en 3,4 en and V1 Where do the 4 GND connections get wired into Why is there only a spot for the positive wire for my stepper psu and not for the negative terminal if you look at the instructable the only power to provide is the negative and positive of the stepper so how would i wire up my stepper and my psu Amazon.com: NEW Genuine MU05-H120040-A2 12V 0.4A 400mA Power Supply Adapter for LEI: Electronics (also on a side note, i ordered the psu from amazon because it said it was .4A which is what i need, turns out its .5A, is that going to be ok if the stepper is .4A (the hbridge is .6A).

All Grounds (0V) should go together, the ground of the 12V, the 5V etc all are connected together at a common point

the 5V goes to all those pins because it is 5V logic input to the chip and those pins need to be either the logic supply or held high to enable the parts of the chip

The positive rail of your stepper PSU goes into the chip to feed the HBridge, the 0V (Negative terminal should all be connected together with the rest of the grounds so is implied that there is a return path

In this case the steppers are NOT wired to 0V or stepper supply + volts, the HBridge chip takes care of the stepper power

The stepper power supply is a weird thing, well steppers are the weird part. they can have a published rating of say 3.3V but be connected to as much as 48 or even 70 or 80V power supply via the stepper controller. it is the controller that governs how much power goes into the motor, not the power supply.

your choice of a 400mA (500mA actual) is a good place to be with your project, it is not too powerful to do any real damage if you make a mistake.

As a side note, I am currently rendering a few youtube videos for my CNC project ( https://www.youtube.com/c/thebreadboardca ) where I am using a 48V 10Amp power supply to drive a 3.2V 2.9A nema23 stepper motor (Well 4 of them actually), sounds crazy right but it is correct, you have to learn how steppers actually work to understand it and that will be the subject of another video i will be doing soon

OK that was very helpful, now there is only 1 thing i'm still a bit unsure about.  for the ground connections.  do i connect the arduino ground to the stepperpsu ground and connect those(as one wire) to any of the ground pins? or do i connect the stepperpsu ground to one ground terminal on the chip, and the arduino ground to a different ground pin on the chip? or does it not matter @peteroakes

As long as you have reasonably thick wires from the chip to the powersupply then you can use the powersupply 0V as you common point

"... or do i connect the stepperpsu ground to one ground terminal on the chip, and the arduino ground to a different ground pin on the chip?"

Connect all the GND pins of the stepper chip together at the chip. That's what TI intended for you to do. (On a PCB the pins would come down to an area of copper that would tie them solidly together and also provide for some heatsinking. In your case (400mA), it looks as though what you're doing falls within the capability of the device to dissipate power from the package alone, though you might want to add some heatsinking anyway in case you want to use it at a higher current or simply to improve the long-term reliability)

an old motherboard and pull one from the small chips on the board is one possibility if you have access, if not there are plenty available from element14 (Newark / Farnell) or even ebay, search for stepper controller heatsinks and it should bring something up but as Gabriel stated, for the low current your switching, you probably wont need one, when you are running it, feel the top of the chip with the back of your hand or carefully with a finger, if you cant keep you skin in contact for more than  a few seconds then you need a heatsink, otherwise your probably good to go

Peter

I always like the wet finger.

It gives extra time for the slow brain to register the finger is saying "S..T THIS IS HOT" ...

and the sound of sizzling probably will reach the brain faster too

and the sound of sizzling probably will reach the brain faster too

Funny you should say that because I have witnessed that.

A funnier thing was a guy at work who was so used to working with transistors and fingering them, that the first valve receiver he worked on, he got a belt of the grid cap ...