nophead: I would expect the same, and it is really weird. Again the data of the stepper motor: 1.5mH of one coil 0.9Ohm of one coil. It is connected as bipolar serial, so I think the above becomes: 3mH of two coil connected serial. 1.8 Ohm of two coil connected serial. There is a 0.5Ohm resistence (which I measure as 0.6 Ohm with my multimeter) in series with them, so finally we have this loadby khiraly - Controllers
So now the images with higher current settings. The 12V supply (+12V): The GND (-12V): The zoomed-in GND(-12V): The output A: The waveform of rsense A: A zoomed-in image of rsense A: An another zoomed-in image of rsense A:by khiraly - Controllers
So now a bit of photo-tour. I have repeated the procedure, I have zoomed-in images too. When "normal" current was set, the waveform of the power supply (+12V) looked like this: The GND (-12V) of the power supply looked like this (zoomed-in). When zoomed out there were about 2V shift (i dont have that image, but I do have when the current was high). So it looks like there is only 10V, but itby khiraly - Controllers
Larry: It's a hungarian store located at Budapest. Site: The price is 689.98HUF (from five: 611.12HUF), which means 3.44USD and 3.04USD respectively. I dont think it is a viable solution outside of Hungary because of shipping costs.by khiraly - Controllers
> Please can you zoom in and show the current chopping waveform. It may > just be spikes going to zero. Sure, I will repeat the experience, and zoom into. (sadly in qtdso I can zoom in when im measuring the circuit, I cant zoom afterwards or save my data (for later observation).) Summarizing: I built three boards. It turned out finally, that on my second board I had a short circuit (thby khiraly - Controllers
Ups, I forgot to regulate the power supply to 12V. (it was on 7V) Now the power supply isexactly on12V (12,03V to be exact) The waveform on Rsense: The waveform on output A: If I turn the potmeter more, the duty cycle does not really change, but the waveform become uglier (also the power supply indicate that he is delivering only 9V):by khiraly - Controllers
By the way, if I turn the potmeter, the maximum current will look like this: So its 200 mV peak, that means the current is 400mA maximum! Its not even one quarter of the maximum current. So Im back to my initial suspect, something is not rightby khiraly - Controllers
Thank you guys for the tips. I have post also two more pictures. The motor is running at 3000us(down), 2us up. So its about 1.5ms/step. Placing the oscilloscope on either A,B,C or D makes identical waveform. (too bad, that I can only use one channel). The waveform on the output A looks like this: And the waveform on Rsense (either A or B,again its the same waveform) looks like this: So onby khiraly - Controllers
> Normally the chopping frequency would be chosen to be about 20KHz so > that it is inaudible. You also want it considerably faster than your > step rate. Is it changeable? I think the 20kHz is hardwired into the l297 chip. Finally, I fried 2 of 3 l297 chips.I dont know how I did it. This is the most expensive part of the whole driver board. I will also try connecting as bipolar pby khiraly - Controllers
> If that is full stepping then 1.3ms / step would be ~150 mm/s on a > Darwin, which is about the speed I get without any ramp up. To go > faster you may need acceleration. > How fast were you expecting them to go? I have no idea. I have just built a single sided stepper motor driver board following the wiki. And there are an exerciser code at the end. And my setup just could noby khiraly - Controllers
If somebody are interesting, here are a bit of tutorial what the potmeter is for. When there are no step command (the drive is idle) the waveform is looking like this: When there is not enough torque to even turn the motor, it looks like this: When the motor turns, but I can hold it with my fingers, to waveform is like this: If I raise a bit more, and I cant anymore hold the motor with myby khiraly - Controllers
nophead: I think I get the idea. I have played a little bit. Here is my simple code: #define stepPin 4 #define dirPin 5 void setup() { Serial.begin(9600); Serial.println("Starting stepper exerciser."); pinMode(stepPin, OUTPUT); pinMode(dirPin, OUTPUT); digitalWrite(dirPin, HIGH); digitalWrite(stepPin, LOW); } void loop() { digitalWrite(stepPin, HIGH); delayMicroby khiraly - Controllers
nophead: yes, I meant mechanical load. Good to know, it is not really related. Viktor: I have mounted a bigger heatsink (It was a video card's heatsink).by khiraly - Controllers
I have a variable voltage power supply, at which voltage do you want that I repeat the steps? (8?,12? 17?) I will do the experiments at this evening.by khiraly - Controllers
Ok. I was expecting something stupid and simple (like a short circuit, or open circuit). I will do the following things: - mount a much bigger heatsink (for Viktor,I thought that without load, it is not THAT important the size of heatsink. - write test programs for different speeds. It will not switch the direction or increase the speed. It will be constant. - I will make images of the outputby khiraly - Controllers
Here are the photos of the board (top and bottom): You can see it at higher resolution at:by khiraly - Controllers
Ok, I have installed qtDSO, and made some oscilloscope image. Note, it looks like, the channel B (yellow) is not working, it is always looks like channel A(green) no matter what I touch with. So it looks like, that at higher speed (step_a_full.png), there are multiple oscillation between the line voltage (about 8 volt) and GND. And in general the signal looks really awful. Could somebody postby khiraly - Controllers
jbb: thank you for your advices! > 3) use an increased supply voltage and get the L297 to do current > switching for you - a nice elegant solution. I have a voltage variable power supply (0-30V), increasing the voltage does not make any differences. (apart the leds are glowing more). I increased to 20V, and the problem still stayed there. I'm a bit scared either increasing the 12V orby khiraly - Controllers
schematic: board bottom: board full:by khiraly - Controllers
> Theres a flat side on the silkscreen (pointing upwards), match that > with the flat side (longer leg) of the LED and you're okay winking smiley Sid: those leds are not bicolor? So two leds built into the same package. So if using normal led, you can put in it in either way it will light up. You should use two normal led inserting one in other direction, and this way will be a functionby khiraly - Controllers
I have used HER308 diode, datasheet: Im using single sided board and self-made. Maybe there is short circuit somewhere. (but I have checked many times). I will upload high resolution images from the board (top and bottom side). Im also packaging eagle file. But really, I didnt change any relevant part of the datasheet (replaced the bipolar led with two led. I think it is safe. And for the moby khiraly - Controllers
> umm the datasheet says it's 0.9 Ohms per winding, not 1.8 If I connect as bipolar parallel, the resulting resistance/windings becomes 0.9Ohm. Maybe it is an error in the datasheet.by khiraly - Controllers
> afaics your wiring on the stepperboard > should be yellow, blue, green, white (in ABCD order) I connected in this order. (you can see on the video too, but a bit hard to recognize the colors)by khiraly - Controllers
sid: I have buyed from here: It says the resistance are 0.9Ohm too. I have double checked (I buyed three identical motor) all of them has 1.8 Ohm resistance per windings (yellow-red for example). The L297 driver chip has normal temperature (I can touch it). Adjusting the trimpot doesnt make difference (motor does not turn and the leds fade out).by khiraly - Controllers
Here is the video: Any idea is much appreciated.by khiraly - Controllers
Hi! I have built a stepper driver board, it only works if the speed is slow. If I increase the speed (or simply I try to execute the stepper motor exerciser from the wiki), the motor skips steps, and at higher speeds it simply stops, and make weird noise. The motor has no torque (this is why he miss steps) No idea why this happens. Until tomorrow I will upload a video to vimeo.com (more than 3by khiraly - Controllers
If there is interest, I will make a complete (with photo) tutorial.by khiraly - RepRap Host
I have done a board, and I propose to add this two layers when printing. 20 - Dimension (the rectangle around the pcb) 52 - bDocu (bottom text (mirrored when printed))by khiraly - RepRap Host
> I don't have start, end and checksum because they are all handled by the > UDP / IP / Ethernet protocols. Checksum implemented in the application is useful because if two independent persons write software (micro-side, computer-side), it helps debugging and troubleshooting. Really, its a must-have Our setup was: Touchscreen -> server1 -> database-server -> server2 - -->gatby khiraly - RepRap Host
it is a bit similar what i have done in the past: End the reply was: [1byte][1byte][1byte][ 6bytes ][ 1byte][ 1byte][1byte] It is like yours: command - command parameters - "magic number" id - sequence number Start and end code was required by a plc (and all my commands was fixed length: request 11bytes, reply 12 bytes). I had checksum (what you dont), which was extremely helpful whby khiraly - RepRap Host