I have tried some many times on two different computers; both Win7 64bit, but the GUI just won't run; nothing happens when I double check on the execution file. Is there anything I should install before running the GUI?
Hi John,
Thank you for the waveform captures and layout.
Could you please monitor the charge pump voltage on your revB board. What do you have on your revA board? Is revB the same voltage? at least 20V on the charge pump pin? You might be losing your charge pump so please make sure you have good connections on CP and VCP pins. I hope this helps.
Are you planning on supplying Vcc and VM from different sources? if yes, as long as you provide a constant voltage to you 2V motor you are okay.
If you are planning on using a single supply a better solution can be the DRV8830. Have you looked at this device?
I am designing a custom controller board for controlling steppers on a telescope mount. For my initial prototype (Rev A) I used two Pololu DRV8825 Stepper Motor Driver Carrier boards plugged into a custom board design. This prototype drives two 1.5A NEMA 17 bipolar steppers and works very well.
I designed a second board (Rev B) using three DRV8825 devices mounted directly on the board and I am experiencing erratic motion on all three motors and see some serious irregularities on the current waveform as shown below. This trace was captured while in full step mode with a step rate of 40Hz. to a single NEMA 17 stepper. The corresponding trace of the Rev A system looks good.
In looking further into the problem I also see serious irregularities in the PWM waveforms for both A and B outputs as shown below. Again, the corresponding traces from the Rev A system look normal.
I realize that much of the layout is not according to recommendations. After reading most of the DRV8825-releated posts on this forum I realize that much needs to change here. Previously I had not seen the EVM so I will use it as a model for the next rev.
I have tested all three DRV8825's on the board and they all show this behavior. Has anyone seen anything like this in the past? Is there anything in the information here that would point to a possible cause? I will be redesigning the board in any case but I would like to have an idea of what caused this before I do that. My only theory at this point is that my solder reflow method resulted in the devices getting too hot and being damaged. It seems unlikely to me that all three devices would be damaged in the same exact way however.
I am using the DRV8825 driver to microstep a stepper motor in a circuit with the following parameters:
Motor coil resistance: 2.5 Ohms
Motor coil inductance: 2.5 mH
Motor supply voltage: 28 V
ISENA/ISENB resistance: 0.220 Ohms
Current setting: 1 A
Decay mode: fast
The motors successfully rotate given step commands. I do not have a current probe for my scope, so to verify microstepping operation, I attempted to make a measurement across each coil's current sense resistor. When the H-bridge applies power across the coil, the voltage on the sense resistor is proportional to the winding current, since it is in series with the motor. Since we are using fast decay mode, this is also true during decay, however, the polarity through the coil swaps, so I need to be aware that the voltage at the sense resistor will invert. Taking that into account, I expected to see a waveform similar those in the DRV8825 manual for the front half of each PWM cycle, with more severe fall rates due to the fast decay vs. slow and mixed shown in the datasheet.
However, I'm seeing the following voltage trace at ISENA with the motor holding:
The most confusing thing is that there are segments exceeding the 33.3 us that the 30 kHz PWM would chop at. Is it not possible to analyze the current draw behavior using the sense resistor voltages? Am I misinterpreting the meaning of this trace?
Can you advise the most common reasons for this, to check. The application is TEC controller. the load is around 1A, but it gets hot and shuts down. It is heat sunk and also the bootstraps caps are the correct value. Is there anything else to check?
One method to control the speed of the stepper motor is to set the CONFIG bit to a logic high. This sets the DRV8834 into indexer mode. Using indexer mode, each step input moves the motor. By increasing and decreasing the frequency of the step input, the motor speed can be increased or decreased.
i am working on stm32f1 mcu and i have interfaced DRV8834 driver ic to run 20DAM20d10-k stepper motor,im using PWM here.i am able to run motor but now i want to control the speed of motor(increasing and decreasing).so how to control the speed of the motor using this driver ic.i am new to motors,i dont any prior idea about stepper motor.so please help me.
please let me know if you need more information from me.
That is normal, thank you for verifying. We are running out of options here and the one remaining is the layout. I am sure you cross checked all inputs from revA and revB boards to see if anything looks different on those signals.
Then for the layout, please follow the example provided as you mentioned before. One main concern is the two 12V rails for VMA and VMB, I would bring only one trace close to the device, then split to VMA, VMB pins to shorten that path. The layout provided does this, so I would suggest to follow it as much as possible. Thank you.
YES , I planning on supplying Vcc and VM from different sources, motor specs: Voltage range for use: DC:1.5V~4.5V, Rated load: n=200g-cm , At Rated voltage and rated load<=80mA, Provide 2V power supply on the VM pin, Can drive the motor to work？
The schematic for the HV Mtr+PFC kit can be in ControlSUITE under: C:\ti\controlSUITE\development_kits\HVMotorCtrl+PfcKit_v2.1\~HVMotorCtrl+PFC-HWdevPkg\HVMotorCtrl+PFCKit-R1.1
