Thanks capellacnc & groundFungus,
It's clear to me for the supply question. I will use your example to compute all my amps.
I don't understand your calculation here. Why 100/71 ??? If it's 71 % it should not be 71 / 100 ?
The datasheet shows that only 71% (0.71x) the current limit will be drawn by each phase, so set the current limit proportionally higher - (100 / 71) * 0.86 = 1.4 * 0.86 = 1.2A. You are setting the current limit to 1.2A so that the motor still only gets 0.86A!
... A
Hi,
Another question that I have in mind is about the bulk capacitance of external power.
In the datasheet of the DRV8825 and in some scheme that I found on the Internet, It is recommended to have a bulk capacitor between the power supply and the motor drive system to limit the variation of the current.
I understand the problem but I don't know if the bulk capacitance is already in the external power supply or if I had to add one more in the circuit.
For the moment I use those external power (link : https://fr.farnell.com/traco-power/txl-100-0534ti/alimentation-metal-100w-24v-2a/dp/1284192).
... A
I believe that the 100uF cap, in the schematic, between Vmot and ground is what is being referred to. That power supply looks OK.
Here is the scheme with an Arduino. I don't know if the capa is already integrated in my external power or not.
... A
This bulk capacitor is an additonal component, that should be placed as close as possible to DRV8825 board. And 100µF is a minimum. More is better. It is needed for the driver to work properly.
Hi TomGeorge,
Sorry, It corresponds at the picture that I send in #22.
Hi MicroBahner,
This bulk capacitor is an additonal component, that should be placed as close as possible to DRV8825 board. And 100µF is a minimum. More is better. It is needed for the driver to work properly.
It's only for the DRV8825 or it's the same for others drivers?
As recommended to me in another post, I tried to use the proper driver of the pump to have better results. (I choose a TB6560 or a Pololu for the price, the driver recommended with the pump is really expensive (100$).
But when I look the electrical connection details of the datasheet (As you can see here), I have the impression that I need an ESC to control the voltage (Pin 8).
For any steppers, I want to use the AccelStepper Library (Here) because I can't have a blocking function as delays in my code.
I don't know if it is possible to use this library to control the speed of my industrial driver.
.... Alex
From the A2 / A4 Stepper Drive data sheet that you linked:
Driver Type Full H-Bridge for 2 phase unipolar stepper motors
The DRV8825 and TB6560 are drivers for bipolar stepper motors.
I didn't notice that but I think it's an error of the manufacturer because the two motors that I use (15QQ and 9QQ are bipolar).
... A
It is needed for all current drivers. I suppose the bigger ones as TB6600 and similar include that internally. But all these small boards in the DRV8825 format need an extra bulk capacitor. It's too big for these small boards to be on the board.
Hi,
No, actually draw your schematic from your project, reverse engineer and produce a PROPER circuit diagram.
Label pins and components, note what colour wires you use and where form the stepper, please.
Thanks.. Tom... 
Hi,
Does the circuit you posted work?
Can you please post your simple code to test that the configuration works?
I have lost the spec for your stepper, can you post link to data/specs or part number?
Thanks.. Tom....
Hi Tom,
I haven't tested yet, I don't have capacities in my lab.
For the moment I test several shields to compare them (Full step and standard mode).
The TB6560 works well but because I don't found the datasheet of the TB6560 that I use (only the TB6560AHQ inside the board), I can't understand the full possibility of the board. For example what the meaning of EN+ or EN- (I supposed it's for enabling the motor to work or not) and why CW- and CLK- are connected to the ground. I only found Arduino tutorial yet.
As I said, I haven't tested the Pololu because I haven't a capa. I wanted to test this part because it seems more accurate with my stepper (Amp low). I tried to limit the current with a multimeter and a screwdriver but my voltage was oscillating and it's was a bit clumsy (I have already so welded the pin and the connectors so I can't use a breadboard for this step). To choose, even it's less accurate, I prefer to use switches as we can found in a TB6560 to limit the current. Moreover, I don't like the idea to add one more capacity to my circuit.
Finally, I tried the industrial driver that I bought with my pump. I wasn't sure It could be used with an Arduino but it works well if I send a PWM signal. (you can found the datasheet in post #27). It's expensive but certainly more stable so best for very long term use. Here again, I don't understand the all capabilities of this driver yet. I have two pins (Ena and On/OFF) which can be connected to the ground or disconnected. It can be an interesting function to use those pins. So I will try to connect a relay between the Arduino and the shield to commute those pins (Because I supposes I can't say "Pin X connected to the ground or Pin X not connected" with only an E/S Arduino, of course).
I will continue my tests, thanks for your help sirs.
.... Alex
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