[MagooT]

Hello dudes, i have assembled a board using this schematic
http://netikka.net/maggot/bipolar.png

Here's the board layout
http://netikka.net/maggot/bipolar_brd.png
X2-1 is +5v
X2-2 is +15v
X2-3 is GND

X1-1 is DIR
X1-2 is STEP

M1-M4 are the motor outputs


However it doesn't work.
I have measured about every pin using my oscilloscope but the only strange thing i found is that the outputs of the L6203's (pin 1 and pin 3) are high all the time, when i step it slowly (using jog in Mach3) i can see some small flickering around 14-15volt, but i assume it should switch between high and low.

Since i can't find anything wierd on the board, i'm asking if anyone can spot any errors in the schematic or board layout, i have checked the board about 10 times for solder bridges or stuff like that so i don't think that's the problem.

Any ideas what to look for would be nice, since i have no idea what might be wrong with this.

If you need more info just let me know, and sorry for my bad english
Greets
// MaggoT

[markcomp77]

I found one error... look R6 & R7 on your design



R6,R7 need to be connected to GND and sense->L6203[10]
look -> http://forum-cnc.pl/index.php?topic=55.0

[MagooT]

Thanks for your help.
I have fixed the problem now but it still won't run.

Another go with the oscilloscope shows that pin 1 on both 6203's now switch between 0 and 15volts, but pin 3 switches between 0 and 5 volts i can hear a small ticking sound from the motor when im jogging but it doesn't move.

When i measure between GND and motor outputs M1-M4 i just see a blinking line at 10 volts on the oscilloscope.

[markcomp77]

Another go with the oscilloscope shows that pin 1 out1 on both 6203's now switch between 0 and 15volts, but pin 3 out 2 switches between 0 and 5 volts i can hear a small ticking sound from the motor when im jogging but it doesn't move.

out1 and out2 should switch between 0 and Vs

1)
data sheet of l6203 is:
Vs Supply Voltage --> min=12V typical=36V max=48 V
its better to use higher voltage...
power supply - on AC24V trafo (DC output about 32..33V)

2)
use new L6203... and make new tests

When i measure between GND and motor outputs M1-M4 i just see a blinking line at 10 volts on the oscilloscope.

make output current measurements... current of winding

[MagooT]

I just found the problem (embarassing) if you look at my schematic OUT1, BOOT1 and OUT2, BOOT2 are the wrong way around on the motor outputs, so i switched them and now it seems to work thanks a lot for your help.

[markcomp77]

I just found the problem (embarassing) if you look at my schematic OUT1, BOOT1 and OUT2, BOOT2 are the wrong way around on the motor outputs, so i switched them and now it seems to work thanks a lot for your help.

do you think about...



making of STEP=1/2 better?
to have equal ful step and half steps...

[MagooT]

I'm sorry, i don't understand what you mean, i'm not good at reading schematics what does it do?

[markcomp77]

what does it do?

it change Vref (=>output current) for half steps...
because of this => torque of motor on full steps and half steps will be equal
because of this => half steps will be more precise

[MagooT]

Ok, thanks.

Another question, i'm trying to run a small motor from a printer (don't have any other specifications for it other than "10 ohms", unfortunatley), and it get REALLY hot just after a few seconds, so i assume i must recalculate sense-resistors or something? Because the chopper isn't lowering the current at all, can anybody explain how to do this?

[markcomp77]

Ok, thanks.

Another question, i'm trying to run a small motor from a printer (don't have any other specifications for it other than "10 ohms", unfortunatley), and it get REALLY hot just after a few seconds, so i assume i must recalculate sense-resistors or something?

yes...
but better is to regulate Vref of L297
look there -> R23

Because the chopper isn't lowering the current at all, can anybody explain how to do this?

use potentiometer (R23) to set Vref
look on any L297/8 driver - make the same...

[MagooT]

Thanks, i googled around a bit and read about vref, this is what i came up with:

Schematic: http://i20.tinypic.com/2emdkx0.png
PCB: http://i23.tinypic.com/28lg9c8.png

This allows me to adjust Vref between 0 and 1.7 volts, should work great.
Guess it's time to etch a new board an try it out

[xinzc28]

Hi Magoot, I made similar driver.

My 10 ohm resistor is always get to smoke because of excess heat.
Do you have this problem?

[vpapanik]

Thanks, i googled around a bit and read about vref, this is what i came up with:

Schematic: http://i20.tinypic.com/2emdkx0.png
PCB: http://i23.tinypic.com/28lg9c8.png

This allows me to adjust Vref between 0 and 1.7 volts, should work great.
Guess it's time to etch a new board an try it out

These are very good plans indeed. Do you have any link information ?

[George_b]

Hi! i am new in electronics and i am wondering how to run my board for my cnc using the circuit with L297 and L6203.

What kind of interface do i need to put between my parallel port and the circuit board.

Thanks in advance!
George

[Thomeeque]

Hi Mark,

please, do you know what publication these drawings come from? It looks to me like some official ST document (similar S-XXXX numbering is used in L297/298 datasheets) but I did not succeed to find it (I've checked ST site and tried to google it few ways including search for S-9388 and S-9389 codes).

I understand the principle but I'd like to read "full story" if possible.

Btw. I'd say that when using simple resistor divider as VREF source it would be useful to use significantly bigger resistors in this mod compared to resistors used in VREF source (e.g. 4k1 and 10k instead of 410R and 1k) as the output impedance of VREF source will mess the 1:1.4 ratio.

Cheers, T.

[aknightlegend]

i am glad that i linked with some one have a good knowledge in L297
i have one problem that i need to step my Bipolar stepper motor in smooth way, as a smooth rise, as i do not need to drive motor as shock pulses,
is it refer to the Chopper circuit? as i try it but the OSC with the RC components not work
and i try to sumulate it on the ISIS proteus but it could not be seen on the Digital Oscilator
please help me , i am stucked in this issue for more than 2 monthes, searching for solution on internet

[lalaabdallah]

I just found the problem (embarassing) if you look at my schematic OUT1, BOOT1 and OUT2, BOOT2 are the wrong way around on the motor outputs, so i switched them and now it seems to work thanks a lot for your help.

hello sir ,
i googled to the same problem with L6203 and ifound your same post ,my Pin 3 is high level ,may iknow what you did exactly because ididnt understand really what you mean by you solution, how you switched it ,please ineed to know because it make me crazy my ship thank you sir