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Topic: L297 stepper motor controller (Read 45848 times) previous topic - next topic


Feb 05, 2006, 07:50 am Last Edit: Feb 05, 2006, 07:51 am by Daniel Reason: 1
PS: it is stocked somewhere in Europe, as the price at this place is in Euro's, five of them...


Well, its been about 3 weeks since my last post on this thread and by now I should have got a working L297/8 circuit. However, the reality of live, with a job and a family, has meant no electronics fun for 3 weeks and zero progress.

However, I have managed to buy the ICs and now I have a little time i've met my first problem  >>>  the L298 doesn't fit onto a breadboard. Looking on the data sheet, it is described as a 15 lead Multiwatt package.

Is there an easy way to fit this IC to the b/b?? Or do I need to go some other way??

Thanks as always / Jonathan



Is there an easy way to fit this IC to the b/b??
You are best to skip the breadboard and go straight to a hard-wired version, since there is a lot of power and noise floating around, and the chip has to be heatsinked in any case.

On a perf-board, put pins 1,3,5,7... in one row, and then put pins 2,4,6,8... in the row behind it. A little tricky, but it works. Some pin-bending required.  

Once things slow down on my end I will design a stepper driver PCB for it that fits on the Arduino... unless someone else wants to in the meantime? I have the working design with schematics.



Mar 02, 2006, 01:54 am Last Edit: Mar 05, 2006, 09:34 am by owd Reason: 1
Hi: this one is a miser solution, but works: I've used an IDE wire (cut it and use each extreme to connect to each file of pins) to put one L298 and one 7805 into a CPU heat sink+fan cooler. It hasn't heatsink grease or mica (I think it's bad).

Thanks for this great post (please, post the schemas ;)!!). Btw. someone could explain how connect the L297 to a darlington for unipolars (or two L297 plus one ULN28003)??




There is a schematic for using the L297 with a unipolar motor on the L297 application notes pdf (not the datasheet).....


its page 15, fig 22.

It involves a darlington array, 4 protection diodes and 4 AND gates.

I'm planning to try it once I get the L297/L298 working together nicely.

Allegro have some new ICs out for controlling unipolar steppers that do the job of the L297 and the darlington array in one chip. I contacted my local sales rep and got some free samples. I haven't tried them yet though. (i'm old fashioned, so I like to learn how to do things the hard way before I use the shortcuts!)



Regarding heatsinking the L298....  If you plan to step your motor slowly, for instance just a few steps per second, will the IC still need sinking?? How hot does that guy get anyway??


Mar 05, 2006, 09:43 am Last Edit: Mar 05, 2006, 11:00 pm by owd Reason: 1
Thanks Jonathan.
Massimo point out that application note in this post too. But after read that little paragraph and look its illustration I can't take anything. It looks like a marvelous egyptian hieroglyphic.
For example: before all the points on this post about bipolars (additions and diferences from the datasheet), is valid the rest of the circuit [L297+L298] with the described  ULN2075B? Does It need corrections? But if I want chopping (I want chopping)... what can I do? How can I do it with the ULN28003 (for two axis driver)?
It's very hard and frustrating... After my first toast-session (one unlucky SN74LS158N) I take it carefully.

Yes, just readed your other post I wrote to the ST and they ask me to local dealers. I mailed one local dealer past week but I'm still waiting for a response :'(.



owd: I love your 3d diagram of the Arduino board.  Did you make it?  Can you post a copy of the original files so we can use it to make more diagrams?


Mellis, now you can say "I met Gollum": No! No! It's mineee! My ownnn! My preciousss!
Obviously it's a bad joke: I'll send you (next time, I don't have the files here).



Mar 13, 2006, 06:03 am Last Edit: Mar 13, 2006, 06:16 am by Daniel Reason: 1
hey all:

I was just rummaging through some boxes and found one of my L297/298 stepper motor drivers. It's about ten years old, and still works like a charm. In fact, I regularly throw it across the room when teaching electronics classes, to demonstrate how simple designs can also be reliable and rugged.

Here's a (terrible) pic taken with my laptop camera, showing the driver unit with the cover removed:


The case is  Hammond 1590B diecast aluminum. In the pic you can see the L298 screwed to the case at the top for heatsinking, DB9 connectors at the bottom and left for input signals and motor connnections, and the motor protection diodes. There's also a  7805 in the middle to provide internal voltage regulation,  and two large power resistors for the L298 current sensing. There are also blobs of epoxy and hot glue on all the hardware, since a loose screw inside something once cost me thousands of dollars and a couple of plane flights to fix it. The whole unit is about one inch by two inches by four inches.

The schematic for this is exactly the same as the one on page 14 of the ST datasheet, with the addition of an LM7805 regulator for the power, a few caps and a reverse-polarity diode.

Jonathan, hope this will help with your UK version!



and one more fabulous laptop photo, showing it with the lid on, ready for throwing.


Mar 19, 2006, 11:04 am Last Edit: Mar 19, 2006, 11:15 am by stinky Reason: 1
I'm back!! - after 10 days holiday in Prague! and feeling fully recharged by tons of beef and dumplings!

Daniel - thanks for the pictures!!  ;)

So, some more questions....

1. As discussed earlier, the schematic on the datasheet has loads of capacitors and some more are needed for the 7805. I can see what capacitance I need but I don't know what kind of capacitors to use?? does it matter??

2. You are using perf board, right?? This is probably a real dumb question, but how do you use perfboard?? Do you just solder wires on the bottom of the board?? Please share any perf board tips or advice!!

The schematic for this is exactly the same as the one on page 14 of the ST datasheet, with the addition of an LM7805 regulator for the power, a few caps and a reverse-polarity diode.  

are the extra caps just the ones required for the 7805 and what is the reverse polarity diode doing??

Thanks a million / Jonathan


Hi all
I'm so glad to find here,for there must be some professions to help me.
My teacher asked me to design a stepper motor driver using l297,l298 and 89c51, which can control the speed and direction.I asked him what should i do first and he answered to me,'do it from scratch'....
I collected some materials of l297.l298 and 89c51 such as datasheets but I could not understand clearly that which pin is useful and how to use.What can I do?I wonder if someone could give me the diagram or circuit of what I need.The schematic will be appreciated greatly and profoundly...
A helpless sophomore.



I made some stepper motor drivers with the L297 and L298 five years ago, and they still work great!

Could you send it to me?


Dear Dizzy

Unfortunately for you, this place is full of professors like me....

If you just get the project done from somebody here you won't have learned anything...

There is a lengthy discussion about the L297/L298 on this forum.. if you read it while not dizzy you'll get all the info you need.

Sorry if this sounds harsh but this is not a place for people to avoid doing their assignments...

have fun while learning



Now I have knew the circuit of l297/l298 from the datasheet of them, but how can I connect it with the 89c51 if noly control the speed and direction of the motor.I think the direction of motor may be controlled using the pin17 of l297.Which pin should I use to control the speed, 18 or others?

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