motor controller L297... need help

[sp]

using an l297 with high amp motors

The reason for a smaller and a larger capacitor is that the smaller capacitor is used to filter out the higher frequencies and the larger for the lower frequencies

i c tht line i understand everything... and also wad i used to see y need so many C... now i start to understand... can i know who are you?... impressive...

for the home output, i connect it(home) to a 10kohm and the 10kohm(another node) to Vcc(5V)...and my controller read from the home output at the same time....

i use a multimeter to check the home output... all of the time it is 4.7-5V(high)... when i assert the reset_not(reset_not = 0 for L297) the home output is 1.2V(multimeter reading)... i assume tht when i assert the reset_not... the translator go back to 0101 state... so i think when it is 0101 state it turn on the transistor for the home, so the home is pull down to the gnd wth a transistor voltage drop(Vce) of 1.2V??.. i hope my concept is wrong too....

for the motor, i hav try many frequencies,,, but only 1000Hz works smoothly.. all other shakes a lot n very hot... when i used 1kHz, it very smooth n less hot(mayb)

100Hz i tried and shakes lot, first few try on reverse direction is working, after tht no respond D it continue turning same direction...

and one weird thing is tht the torque is higher when it spin faster... it is harder to stop it wth fingers than when it is running slow(easily stop)...

thank you Marcel Majoor... grateful..

my warmest regards,
sp

 

[Marcel Majoor]

what should be the chopper frequency for l297

1.2V for a low level of the HOME output is not good. You are correct to assume that, when the RESET is activated that the device is at the home position. However, according to the data sheet the HOME output is: 'The transistor is open when this signal is active'. This means that the transistor (if I am interpreting it correctly) is -not- on, hence the pull-up resistors are pulling this output to +5V. However (yet again) you do measure +5V at other times ..... I must assume that I interpret this incorrectly and that the HOME output tranistor is on when the device is in it's home position. But still, the incorrect 1.2V. I can only think of the other circuitry connected to the HOME output which 'generates' this behaviour. Try checking the home output with -only- the pull-up resistor, and then, when the output is still that high, you might assume something is wrong (with the device maybe).

General note: An improper power supply (noisy, underpowered, ..) can generate strange effects (e.g. a device can reset itself again and again).

 

[sp]

l298 maximum frequency dc motor

thank you Marcel Majoor... again

everythings working now.... u know wad happen, the ST L298N is defect, i change n everythings work fine.

how i find out?.... i plug out 2 wires(same phase) out of the circutis n i find out the motor still moving, but when i plug another 2 wires out, the motor isn't run anymore...

i check chip by chip n finally found the L298N is broken...it is murphy's law...the last chip i check is faulty, y it is not the first chip?...

actually wad is the rate failure of an IC, i heard tht ST quality is bad..true? like the dual diode half bridge L6210 IC... i check the diode action using multimeter, every chips i bought is different, but it is working...

then i check short circuits on the L298N some pins shows short circuits characteristic on one chip but not if i try another chip

wad i feel weird is tht the motor can run wth single phase...but torque is low i suppose..

wad u interpret is correct, when in home state the transistor is open circuits...so the home is high... tht day i read 1.1 to 1.2V is when transition, it is flunctuating so the averange is tht value i suppose

i can read the step D... n another prob is my controller code is handicap as well... there is some errors on coding....now settle.

many many many thanks...


my warmest regards,
sp

 

[BHATKAL]

l297 clock speed

Hello sir,

i have some doubts regarding the stepper motor controller L297.....


There is a three mode of operation isn't it....(Half step mode , Full step mode ( Normal drive mode , Wave drive mode))......if the active high on the Half/Full~ pin is taken as half step mode na.....and active low means Full step mode....in that how to differentiate between wave drive and normal drive.....i know that if translator output is 2,4,6,8 wave drive and 1,3,5,7 normal drive......but we are getting normal drive and wave drive......if we want to run the motor in normal drive mode only ....is there any external setting for that........is there any effect to motor if i simply make the port pin low....................

 

[sp]

control input in l297

hi BHATKAL

phew! it used to be my final year project and i now have difficulties understand it. it's been some time...

ok let me try to help on the Full Step Mode. it has 2 modes: normal and wave drive.

for normal it's easily determine, assert reset and make sure it's in Full Step Mode. you get normal drive.

for wave drive, you need to switch to Half Step Mode first and let the translator go to any of the 2,4,6,8 state and change to Full Step Mode, this you will get wave drive.

i dunno is there any other way to obtain wave drive mode, but the method i mention is from Marcel Majoor.

You are welcome

 

[Vash1011]

l297 darlington array circuit

Hi, I am trying to control a stepper motor with a microcontrollr which should be able to send commands to the motor and make it move a certain number of steps either CW or CCW depending on the key pressed.
It is a colour wheel motion.
10 colours = 360deg = 200 steps using a 1.8deg step angle motor.
I am not being able to choose which motor to use: Bipolar or Unipolar? javascript:emoticon(':?:')I know it doesnt matter in this case, but I would like to control it using the L297 and a driver to make the software from the microcontroller shorter and use 2 pins of the microcontroller, rather than 4 pins.
In case of using Bipolar and L297, I read the datasheet of L297, but its quite ambiguous. My motor would be driving at less than 1A/ phase. So I should choose to use L293E rather than L298, though I dont find any reason why I should not be able to use L298? Please advise.javascript:emoticon('')
Next step is to make the connections.
I found a really useful connection here:
**broken link removed**
According to that circuit, my microcontroller should be sending a set of 1s and 0s with 5ms in between per step for one colour movement, and then, after 20 steps(meaning that it has eached the next colour), a delay(which could be 1second) is sent and then the 5ms clock pulse are sent again. To choose CW or CCW, this should be connected to a pin on the microcontroller to be set high or low according to the key pressed.
I have a few questions:
The wheel will have a small part cut out(an opto switch interrupter to sense the reset position) Once, the opto switch receives the signal from the emitter, it sends a HIGH to the microcontroller which should then make the motor stop. This is the RESET position of the motor.
Is there any way to make the motor, driver, translator 'remember' that reset position so that whenever a single colour change is desired, it goes back to the reset point and then the motor turns according to the number of times the key for 'next colour' is pressed. Please note that there should be two keys: one for next CW colour and one for next CCW colour.
One key should be making the motor turn at a specific speed per colour, its the speed the wheel changes from colour A to B, not from 1 step to the other. so basically, its the delay between every 20 step commands sent to the motor.
While the motor is moving,say CW, it moves step 1 to step 200 until the optoswitch sends a HIGH to the microcontroller. At this specific point, the motor must stop(all wires should be 0000) and then turn CCW until the optoswitch again sends a HIGH to the microcontroller where the motor then turns CW...this goes on continuously.
Please note that the optoswitch is primarily there for the RESET position so that a 'good' colour change takes place rather than a messed up effect.
If you have a suggestion to the movement of the wheel, you are warmly welcome to advise me please.

My main question:
Will this circuit above work according to my specifications? Any changes you may suggest? Im quite reluctant in choosing the driver, L293E or L298?
Lets say im going to use a 12V 2-phase Bipolar stepper with a 1.8 step angle with a rated current of 0.48A per phase.
So, for a delay of 1 second between colour:
The input to Clock should be, since it is 'Pulse Low to step', a low from the microcontroller will make the motor move 1 step:
0(5ms)1(5ms)0(5ms)1(5ms).....x 10, then (1 second high-stops the motor completely)0(5ms)1(5ms)0(5ms)1(5ms).....
This sequence goes on for 200 steps until the opto switch sends a HIGh.

Please advise on the softwre and circuit side of the motor movement?
I read about using the ULN2003 transistor arrays, but this would implement tougher programming, i presume. Whereas I just need these movements:
1.....Move from 1 colour to the other with 1 second delay, 0.5second delay, 0.1 second delay, 0.05 second delay, 0.01 second delay and then 5ms delay: these are basically the different speeds I will make the motor move, 1 second being slowest and 5ms being the fastest.
Here is the motor:
**broken link removed**

2.....After moving all 200 steps, move back in the opposite direction to reach back to the RESET point.

3.....If the 'RESET' key is pressed, the motor should move clockwise until the optoswitch sends a high to the microcontroller and then the motor stops.

4.....If the 'CW NEXT COLOUR' is pressed, the motor should move to the next clockwise colour.

5.....If the 'CCW NEXT COLOUR' is pressed, the motor should move to the next anticlockwise colour.

That is all I could find out that my colour wheel and motor would do, improvising for a hopefully small program..:-(

Please help me decide on the chips to be used because I need to order the motor, the L297 and the driver by today evening!

Thank you very much for your patience for reading such a long message.

Thank you very very much in advance for helpful.

 

[patweadock]

l297 vref voltage

Can you use one of the microcontrollers registers (or a memory address) to keep a number (0 to 200) indicating present position? then the controller would know how far it has gone since seeing the index sensor and your code would always know where the wheel is.

 

[Vash1011]

l297 clock signal

Can you use one of the microcontrollers registers (or a memory address) to keep a number (0 to 200) indicating present position? then the controller would know how far it has gone since seeing the index sensor and your code would always know where the wheel is.

This sounds fantastic.
So, for example, to choose colour B which is 60 steps after the RESET(SENSOR), the count from the memory address would be Present position+60?

What about the circuitry? will it work on the circuit i sent above?

 

[patweadock]

orcad part for l6210

Though I've used the l298, it's hard for me to understand your circuit description without a schematic. The current sense feedback is usualy needed if one wants to over-voltage motor coils for max torque. If that isn't required of your application, you wouldn't need it. I'm curious about your application though, usualy, color wheels are turned at a constant rate while the light shone thru them is pulsed on at the color position desired, like with DLP projectors or "propeller clock" operation. An optical index position sensor is used with these too.
Also, the easiest way to sequence a bipolar stepper is with 2 exor gates and 2 D type flip flops, the outputs from the flip flops drive four MOSFETS. You would only need 2 pins of the controller for this; step and direction, with the controller adding or subtracting steps from the position register according to the direction bit.

 

[Vash1011]

l297 plus a quad darlington array

Though I've used the l298, it's hard for me to understand your circuit description without a schematic. The current sense feedback is usualy needed if one wants to over-voltage motor coils for max torque. If that isn't required of your application, you wouldn't need it. I'm curious about your application though, usualy, color wheels are turned at a constant rate while the light shone thru them is pulsed on at the color position desired, like with DLP projectors or "propeller clock" operation. An optical index position sensor is used with these too.
Also, the easiest way to sequence a bipolar stepper is with 2 exor gates and 2 D type flip flops, the outputs from the flip flops drive four MOSFETS. You would only need 2 pins of the controller for this; step and direction, with the controller adding or subtracting steps from the position register according to the direction bit.

Thank you very much for replying.


Actually, im building an illuminator, the light source is a 12v 75W halogen lamp, it cannot be pulsed nor dimmed. Its on constantly.
All special effects are made using the colour wheel, the stepper which are thus controlled by the microcontroller.
It is precisely important to use a microcontroller as the title of the project is Microcontrolled POF Illuminator, my Final Year project, for which i have a poster presentation this coming wednesday...:-(

I am suggesting to use L297 as the translator and L298 as the driver whilst the microcontroller sends the clock pulse and direction pulse according to the program.

So, the wheel will be moving either clockwise or anticlockwise and the speed of rotation of the wheel will be determined by the frequency of clock going into the L297, or am I right?

The schematic for using bipolar motor as well as unipolar motor is attached. It is from a website i mentioned earlier.
Please ignore the connections to other L297s in the schematic.
According to the schematics, i see unipolar as being the easiest to implement, but what is the purpose of R7?

How should I program the stepper to move CW and then suddenly change direction? this will include a STOP phase and then re-power the wires, does this have to be included in the clock pulses or does the L297 do it within the translator?

 

[patweadock]

l297 cheap

You don't really need to program a "stop", where you apply 0V, in fact, applying 0 V may allow inertia to move it a couple more steps, where if you just stop pulsing it to effect a stop, the last phase power will still be applied, which will tend to hold it in place. Then maybe a very small delay to dissipate inertia, then change the direction bit and start stepping again. I doubt you need the delay though.
R7 is used with R6 to make an adjustable voltage devider for Vref. This is compared internaly to Vsense. When Vsense is greater than Vref, phase power is turned off. Then it waits for Vsense to go to 0V before turning power on again. This is what limits the current in the coils from deystroying itself thru heat. It allows you to apply a greater voltage than what the motor is rated for. When you apply voltage to an inductor (a coil), the current is not instantaneous, it has to wait for the magnetic field to expand, conversly, when voltage is removed, it takes a while for current to stop - until the mag field collapses completly. This time is the L/R time constant. This confiquration for powering stepper motors is called "chopper drive".

 

[mona653pak]

l297 noise

i have made l297/298 combination and it worked fine. Now for larger amps, i have replaced l298 with discrete MOSfets bridge. the problem is when i run turn on the supply voltage only 1 of my MOSfet becomes very very HOT and burns. meanwhile the motor holds the torque but does not move even if i give clk to it.

one of the things i am doing is i am leaving sense terminal on l297 as FLOAT value that is i am not connecting them to any terminal. as far as VREF terminal is concerned i have distributed 5V through 10k and 2.2k resistor leaving 1.4v at Vref.

Please help me

 

[Akshatha_H_Rao]

Stepper Motor current

Dear Sir,
I wld like to knw wat "ll be the current required t wen stepper motor is at a position for sometime ie if its made to stay in particular position
Bipolar stepper motor is being used
current limitation per coil is 250mA
Driver used is L298


Thanks

 

[patweadock]

If some force is being applied to the motor and you wish it to resist that force (and stay stopped) then current must be kept flowing in the last phase that was energized. The current would need to be proportional to the force. There is usualy a parameter supplied with the motor called "Holding torque" and is stated with the current required to produce this torque.

 

[rexjohn4u]

Re: l297 home

thanks dude... this info s a lot worth

---------- Post added at 17:49 ---------- Previous post was at 17:39 ----------

please help me. am using the same circuit.

my controller hangs after some times connected to l297. i didnt connect the l298. i just wanna test the output ABCD of l297... but that time ths problem arises. wht?? i had connected a 22ohm res and a .01uf cap as OSC means its a 6.5khz freq and the clock freaquency i used s 3hz only. i didnt use that home pin and sync pin.. whts may be the cause for hanging of the controller?

---------- Post added at 17:59 ---------- Previous post was at 17:49 ----------

also i connected half/full to ground. my purpose was for a full step.. but i actually dont know wht s tht full step... and i dont want to. my purpose s to rotate a step angle when a clock pulse s given. help me in tht too. is my problem due to the clock pulse width. i tried with a 80% and 50% but result s same. controller hangs after 5-10 sec

 

[patweadock]

It may be that the sense lines going into the l297, since not connected, are sensing high, which would turn off the outputs. Probably when you get the l298 connected correctly, it should run fine.

 

[rexjohn4u]

thanks for the info... wil check it out. is that schottky diode important?? what if i dont use tht?

 

[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

 

[farhansinghera@yahoo.com]

Re: l297 clock

Will you please provide me programing file of above bipolar steppper motor.