Communication issues with the SlushEngine


One thing I noticed is if a move a stepper by hand, it generate a current that goes all the way up to the raspberry pi and the red light on it flash, as well as the blue light on the SlushEngine.

I am no electrical engineer, but it look like the current can pass beetween the drivers and the raspberry pi.
My only option is to try with a new raspberry pi, using Raspbian.


Using raspian, no results so far.


I ordered 2 more SlushE piHat 2 weeks ago to replaced the original model X I got thru Kickstarter and they finally shipping it today. I sure hope I will not run into the same issue. I will keep you update on how it go when I got it next week. Good luck!


Good news, it was the raspberry pi that was defective somehow. I noticed that it was getting very hot lately and had to constantly use a cooling fan. Maybe when the other slushenging died, it also killed my raspberry pi outputs.

Thank you for your help ragghvani


Brilliant news!

To avoid damaging the SlushEngine (and Raspberry Pi), ensure setCurrent() parameters values are set slow for start e.g.

motor.setCurrent(10, 10, 10, 10)

and then increase appropriately to get the desired torque. If you set setCurrent(255, 255, 255, 255), it will most likely burn out!

Tip: when you pass parameters to methods, verify the parameters match up with what you are settings in the code. Some of the document help files are incorrect and should be double checked.

It may be worth reading about the L6470 chip

Watch some of the videos of RBX1 Remix Robot


Here is a link to show you my robot arm progress. There is still some work to do. I use a 24v fan with heatsinks to keep the driver cold and it work ! They barely reach 40 °c.


Olivier, The robot look great.

I got my SlushHat and hook it up today and install all the program without issue. I can import Slush without error, but the motor will not move. When I check the communication with i2cdetect, nothing was listed. I guess that mean the slush engine is not connected. I didn’t get any error with the communication either, any suggestion?

The SlushHat use L6470H driver chip and not sure if that need to configure differently.

Any suggestion and help very much appreciated.



The set up looks very tidy. Good work olivier!

Hi Skyice, it’s probably best to create a new thread with your issues. Have you enabled SPI and I2C on the Raspberry Pi?


Now I have a minor problem, sometimes when I move the bigger motors, i ear a weird noise comming from the slushengine and the screen connected to the raspberry pi start twitching. The raspberry pi is powered by a external source, so thats not the probleme. The motor still move correctly to. If i lower the current in the code, it fix the probleme, but I have to lower it so much that the arm is not able to move anymore. The slushengine itself is powered by a 24V 40A power supply wich should be more than enough. Any idea why this is happening and how to fix it?



I got the stepper running today. I don’t think the Hat version use the I2C actively as there is no I/O on board. The motor communicate thru SPI. I have to use motor.resetDev(), then motor.getStatus() before the stepper will run. Everytime I use motor.setCurrent, the driver seem to fault out and will not response to any move command. I am still try to figure out what is the range of the current parameter, not sure if it is in % or amp. Same with motor.getSpeed(), the result not matching the command speed. Long story short, I am finally experimenting with the stepper command. I am trying to get a nema23 stepper to run as fast as possible and I only manage to get 180 rpm with 1/16 all the way up to 1/256. Anything beyond that will cause the motor to skip then stall. I am supplying 24-30V 3.A power to the driver.


I think the L6470 can only do * 7.0 A out peak current (3.0 A r.m.s.). Is that mean, 40A supply will actually not doing any thing to help? I do notice the motor drive better with 30V compare to 24V on my test. With 180 rpm, and setCurrent to 100, the motor only draw about 0.3amp. So I think higher amp power supply actually will not help in this case?


Hi olivier, have you calculated the correct parameters for BEMF for the stepper motors you are using?

Is the power not supplied to the RPi by the SlushEngine?


I didnt calculate that. Can you tell me more about how to calculate it and set it up properly?

Also, if i use my RPi headless, with nothing else than the xbox controller connected to it and wifi on ofc, I dont have the weird noise anymore.


You can find the various documents from ST website, such as Voltage mode control operation and parameter optimization and A Guide to understanding L6470, L6480, and
powerSTEP01 output voltage levels

Is it possible to upload a video with the noise?