[Jykke]

Hi All!

This is my first post here, so I'm quite new. I built a bipolar
stepper motor driver according to the schematic which is given
in application note 470 in the web site of st electronics. The
problem is that the motor takes three steps and then one big
step back to the original position. Could someone have an idea
where the problem can be? There are many fine layouts in the
web, but I would like to have this one working.

enable=5v
reset=5v
half/full=gnd
control=5v
If I ground reset no stepping occures. However, holding moment is present

With Best Regards
Jyrki

[Larken]

Sounds like 1 phase isn't working. Hold the shaft on each step and see if there is no holding power on certain phases. If so one phase is blown or not working.
Post a link to the App note you mention.

Have you tried both 1/2 and full step ?
I used the 298 14 years on small controllers. I use the L6207 and its a much better chip, very tough.

[Jykke]

Thank you for your posting!

The holding torque indeed disappears. The board is done according
to this note: http://us.st.com/stonline/books/pdf/docs/1734.pdf.

It really seems like the another phase is dead. Have you any ideas, why
this can happen? Both of the sense resistor runs quite hot though.

Best Wishes

Jyrki

[pminmo]

It could be a motor wiring issue, a pcb or wiring layout issue also.

[Larken]

Are you sure the motor is connected properly ?
Run 1 phase at a time (disconnect the motor wires to the other phase) and diagnose.
A drive can blow in a flash, just a short, or bad connection.

Your layout is very important, the current path for power and sense res should be very close together. A poor current path can easily generate spikes to blow the device.

[Jykke]

Thank you for your answers. I'll do some wiring
experiments. The Motor connections are OK. I
have a working driver too and it runs the motor.
However, I would like to have my own version
working too. Now I have got some valuable
debugging information.

B,R
Jyrki

[Jykke]

Hello again!

I tried both phases separately. First seems to work. The motor buzzes
a bit and takes clear steps. The other however, "tries" to take steps.
The buzzing noise is not present but there is holding torque. The "steps"
are very little. They can be feeled if I hold the shaft, but they cannot
be seen like in the case of the first phase. Any suggestions?

B, R
Jyrki

[pminmo]

Are you full step or half step?

[Jykke]

It should be in full step mode. Pin 19 on l297 is connected to the ground.

[pminmo]

The phase that is weak could be false triggering on the current setting due to noise or layout. Or you could have a high resistance current path on that phase due to layout.

[Jykke]

Thank you pminimo. I'll try another layout.

[Jykke]

Thank you all for being active in helping me with my problem.
I checked the soldering joints and there were one shortcut
and one unconnected wire. I fixed them and the board is
working OK. I have been quite busy during this spring and I have
had no time to write earlier.

With Best Regards,

Jykke

[mojalovaa]

Hello everyone I have a problem with the stepper driver, the standard scheme with L297 and L298, the Y-axis controller, I was burned, both chips are burnt, I replaced both chips, and is not working properly, all the lines I measured and are good, all the components are correct, power is good, when you connect the engine and turn on the motor controller has blocked me, when I turn the engine to run it simply does not respond and then you can rotate it by hand as much as you like nothing happens, when it is on the computer is turned off, the engine we again be blocked, I need urgent help

[pminmo]

Need more info on the specifics of "the standard scheme with L297 and L298". Schematic, PCB layout etc.

[Larken]

http://www.sparkfun.com/datasheets/R...8_H_Bridge.pdf
The L297/L298 is a 20 year old design.


Check out the L6208, its a really good chip. Very tough and will run up to 50 volts.
Digi-Key - 497-5342-5-ND (Manufacturer - L6208N)

I use the L6207 with a Pic driving it (with microstepping) in a drive i make. The L6207 runs really cool and will outout 2.8 amps/phase @ 50 volts.

Larry K

[mojalovaa]

Yes theat is circuit like data , all parts is new , and work like with old part.
When I conect power suplay motors is blockate , when i wont start motors motor not work but in theat moment is not blockate.
All cuper line is corect , power is corect , X and Z work corect but X not work , when I m make theat controler everithing is work corectly , but in one tame Y is make bummmmm , and I m change all parts in Y , and not work.:drowning:

[Larken]

You need an Oscilloscope to see if its chopping.

[mojalovaa]

You need an Oscilloscope to see if its chopping.

On INH1 have 4.2V while the X and Z axes in these compounds has no power, but the lines are nowhere connected with power, speak only when powered on without the other engines and LPT ports
(flame2)(flame2)(flame2)

[mojalovaa]

Here again the description of the problem we have.
I made a driver cnc with L297 and L298, which worked properly during testing on the Y axis we have burned both chips.
I bought new and replaced, but I always had a Y-axis motor is blocked, I thought it was the chips, a friend sent me a new and again when I have replaced the same problem and the port is always active (+12 V output), percent PCB is burnt down, I made a new plate with only one axis, ordered new parts, put together, and again the same problem, the port is open, take out and put the L297 into an outlet, turn the port open, disconnect the diode from the circuit, weighed again, same problem .
When you turn off the voltage at the plate and measure instruments in the field of semiconductors (diodes) instrument shows the conductivity of the A port to all other ports, I do not know what more to try but I replaced the 4 chip and the same problem, I examined the PCB and I do not see any error, give me please someone can help.

[pminmo]

Could be:
1. a bad L297 that is causing the L298 to fail
2. a motor wiring problem
3. a motor problem.
4. bad components associated with the L297 oscillaor to cause the current regulation to not work.
5. bad component associated with the sense circuit on the L298.
6. power wiring problem....

FWIW, an ebay seller of L297 chips was selling "pulls" of which a significant percentage of them were bad some months back.....