@Thomas_Sanladerer i saw your review of the TMC2100 pololu driver and i got one but i can’t find any good source for how to configure it so it’ll use the SpreadCycle and that i could also set the current from the firmware… could you or anyone help me finding a way?
i’m using a RAMPS1.4
@ThantiK you’ve messed with those before right?
@Olivier_Bilodeau , the RAMPS 1.4 doesn’t support setting current from the firmware, it requires a digipot or some other method. These don’t have any kind of SPI interface, etc for you to talk to the chip - they’re simply step/direction interfaces. Page 9 of the datasheet gives you the info you want to know for spreadspectrum modes: http://www.trinamic.com/_articles/products/integrated-circuits/tmc2100/_datasheet/TMC2100_datasheet.pdf
can you explain how i should calculate the vref? my steppers are rated to 2.6A so i guess i shouldnt max out the drive …
There’s no way the TMC2100 will drive 2.6A steppers. They’re only rated for 2.5A max, and only momentarily. The TMC2100s on the boards I got even struggled to keep from overheating at 1.2A You’ll need to refer to the manufacturers information on the vref - it all depends on the voltage divider setup they use and the sense resistor value.
https://github.com/watterott/SilentStepStick/blob/master/docu/FAQ.md states that the value is 71% of the voltage; so a voltage of 1v will will set the current to 0.71A (RMS) (or 1.41x the amperage you need or 1.69v for 1.2A, 2.82v for 2A, etc))
Speak for Imax instead of Irms and you can say Vref = Imax. I did set up a wiki-page months ago: http://reprap.org/wiki/TMC2100