DRV8825 holding torque


Im using 3 DRV8825 modules to move my 12.5" telescope with worm gears, in that behavior a holding torque is not necessary at all and is just a waste of energy from the batteries. So I just DISABLE and ENABLE the driver every time I need it to use it, but that need a digital pin from the STM32 Bluepill MCU to manage each motor for the ENABLE signal.
There is any way to configure the DRV8825 to maintain 0 holding current without the use of the ENABLE pin when no pulse is send to it?
I think on connecting the STEP pin to the SLEEP pin…

You don’t have 3 pins to spare for individual enable signals? How about just 1 enable pin for all 3 drivers? Even if only one axis is moving, the others are holding but only during the duration of that move.

thanks for the res ponce
yes I have the pins but I just wonder if I can use them on other tasks…


I do not expect connecting the STEP and SLEEP pins together on the DRV8825 to work for a few reasons. The DRV8825 datasheet even states on page 17:

“When returning from sleep mode, some time (approximately 1 ms) needs to pass before applying a STEP input, to allow the internal circuitry to stabilize.”

The DRV8825 does not have a feature for de-energizing the motor when it does not receive any pulses like you mentioned.

As AdamGreen suggested, if your application allows for it, you could control the state of all three drivers with a single digital signal. If you are really low on free I/O pins, an alternative solution might be to use Tic T825 controllers instead of the DRV8825 carrier. The Tic T825 uses the same DRV8825 driver, but supports 6 control interfaces, including I2C or TTL serial, which would allow you to connect all 3 controllers to the same bus. So, for example, if you used I2C instead of needing 3 sets of STEP, DIR, and nSLP signals (9 pins in total), you could control all three Tic controllers connected to the same 2-pin I2C signal (SCL and SDA). You can also use the I2C interface to adjust the current limit of each controller on-the-fly. If you are interested, I suggest looking through the Tic T825 product page and its user’s guide as it has many additional features that I am not mentioning here.


thanks good to know that it exist…
I re-arrange all to use a TLC5947 as an expansion IO port and now I have 4 motors running @ 42V and 12 PWM outputs @12V for heaters and now I have 6 free pins with a normal BluePill isolated from the 42V that comes from a Li Ion batt. I do not feel comfortable dealing with that kind of voltage sharing the same ground with the BluePill… A H11F3 let me measure the 42V from the BluePill… well I attach a drawing if somebody want to see it. Thanks!
Drawing1.dwg (310.6 KB)