Hi,
I want to control a stepper motor, but unfortunately it's too large for standard ULN2003 Darlington Arrays. Since Darlington Arrays aren't more (in my understanding) as an array of some transistors with the same collector. So I was wondering, since the Arduino and it's libraries does all the controlling stuff, if I could just use a logic level MOSFET per channel? Or are they too slow?
Thanks
Hello
It depends on motor coils configuration.
If they are bipolar you'll need 2 H bridges (8 mosfets or stepping motor controler chip like l298)
If they are unipolar then 1 mosfet for each coil
I almost forgot -don't forget about diodes for discharging inductance spikes
Thanks for your help.
They can be operated both way. I prefer unipolar. So one MOSFET per coil would be a very easy controller. Where would you place the diodes? Do you mean to protect the Arduino or the MOSFET? For refreshment, I should put a 150ohm resistor between Arduino and Gate, right?
First, I thought this would be easy, but it seems not. 
Here you can find the datasheet: http://dlnmh9ip6v2uc.cloudfront.net/datasheets/Robotics/57BYGH420.PDF
First, it says it can be hooked up uni- or bipolar. Since the Holding Torque is greater bipolar, I now think its better to hook it up bipolar. But either way, the stepper has 6 wires, which confuses me. I'm now about to try to understand the L298N, probably this helps me.
the remaining 2 cables are useless when using bipolar mode.
L298 is simple to use especialy when you add "binary AND gate chip"
I designed PCB for l298 with AND gate you can find it in attachment
l298.rar (49.5 KB)
Thank you!
Right now, I think it's the best way for me to use a combination between L298 and L5606. See the circuit here:
A few question:
Is the rule -always- that a reset-pin has to be connected to 5V, and if tied to ground the chips resets?
Between pin 16 and GND, there is a resistor, what size would you choose?
And last, there are the two resistors with the value Rsense. The datasheet says; Ipeak=Vref/Rsense. But what is Ipeak? 2A per phase, so is Ipeak 4A? Vref is 5V?
Here is the datasheet: http://www.st.com/internet/com/TECHNICAL_RESOURCES/TECHNICAL_LITERATURE/DATASHEET/CD00000097.pdf
Yes but remember not to connecting it directly! You must connect reset to +5v by resistor (or you will create a short when pulling reset down))
R sense is for sensing current and for short protection and overload protection.
For pin 15 read data-sheet for its function
Thank you for your response. Yes, the resistor between Reset and 5V is important, I know, I use a 10K.
Probably I asked my questions wrong. I know the function, but I don't know how to choose the size of the resistor. For the sense resistors, I don't know what is considered as peak current, and for the other resistor, i don't understand it's function, so I have no idea what would be apropriate.