[OvaR8ed]

I just finished the layout for a L297 - L298 Bipolar Stepper Driver on Vero for Arduino.

The idea is to free up a couple of outputs per driver on the Arduino by using only Direction and Step Pins to control the motor. All the rest can be configured on the driver board by either hard wiring or using jumpers.

This is my first Stepper Driver and I wanted to keep it simple. Since I'm only planning to use a 12V 400mA Motor, I felt the currents will be low enough to not worry about current sensing and the chopper parts of the circuit. Please let me know if you guys have any comments on the matter...?

I've checked the entire circuit quite a few times, starting over each time an error was found and corrected. The circuit passed one complete check and that is what you're looking at.

I need a fresh pair of eyes to make sure of the following things:
1. Will the circuit in the schematic drive a 2 Phase Bipolar Stepper?
2. Does the vero Layout reflect the schematic 100% ?

Resistors connected to 5V = 4K7
Resistors connected to Ground = 10K
Capacitor 1: Boxed Poly 0.1uF 63V
Capacitor 2: Electrolytic 470uF 35V
Diodes: BYW98-200-P238

*Note the insulated jumper at the top of the board

[H500]

12v will give you very poor performance. You should include the current sense and use a higher voltage.

[neilw20]

Without current sense it won't work properly, as designed.
Refer to the application notes. Positioning of tracks and layout is critical.
It can be done on vero board, but you must follow the design rules.
You mightn't get smoke but it probably won't won't work properly when the current sensing lines are misplaced, by just a really short distance.
Similar rules apply to all current mode drivers, and they work very well if the app notes are adhered to.

The chips are designed so that the pinout allows very short tracks from the current sense pins between the packages. Not adhering to these rules, you are doomed to failure.

Your vero board layout needs revision.
The current sense pins on both the chips need to be close together.

Read this to:
http://www.datasheetcatalog.com/data.../7/AN576.shtml

[OvaR8ed]

Thank you for the replies.

Since this is my first stepper driver for hobby application the aim wasn't to run high current steppers. This is why my initial idea was to use the L293 H-Bridge designed for lower current ratings and doesn't come with current sensing capability.

My local Store don't have the L293, but I found a schematic (attached in the first post) showing how to configure the L298 to act in the same way as the L293. It basically just connect the sense outputs of the L298 directly to ground and leaves the sense input pins on the L297 floating... Will the configuration in the schematic work for low current applications?

I'm planning to use a the 2 main coils of a Unipolar Stepper (gutted out of an old printer), disregarding the center taps so that it works like a Bipolar motor. The load across the two main coils are about 8.1 Ohm and about 4.6 Ohm from the centre taps to either side.

I'm planning to supply the attched vero layout with the 12V (yellow) lead from a PC Power Supply (Using 5V Red for logic)... Will it work or am I designing expensive fire lighters?

[neilw20]

If not operated in switch-mode operation I have no idea whether it will work.