Information about the TMC2100 stepper drivers
My experience is with the Watterott brand modules distributed through Filastruder or Digikey. The Watterott sourced modules are highly recommended since they have schematics and lots of info. available where the others, in my experience, do not.
- TMC2100 stepper drivers have somewhat more limited current handling than, for example, a TI DRV8825. This isn't a problem for the typical OnStep user but it's often a good idea to choose stepper motors which the TMC2100 can fully power, such as ones with a current rating of about 0.9A. It's ok (and sometimes desirable) to pick stepper motors with a higher current rating (which will likely be capable of higher RPM's vs. a lower current rating stepper) but be aware that the TMC2100 might not be able to fully power them and this should be taken into account. If you already have 1.8A to about 2.5A rated stepper motors it might be a good idea to test the (very inexpensive) DRV8825 since it has the best current handling in this "step stick" class of stepper drivers.
- There are several versions of the FYSETC TMC2100 modules. And while I have no direct experience with them I suspect that some leave the CFG1/CFG2 pins electrically disconnected (require closing solder jumpers to enable the pins should you want other than 16x stealthChop mode.) There may be other brands/variations/models with problems out there so be sure to read-up on the brand you end up with!
- If using the SilentStepStick drivers be aware that there's a power up sequence requirement: "When using an external supply, make sure, that VCC comes up before or in parallel to 5VOUT or VCC_IO, whichever comes up later." I setup my controllers so they can't be powered from a USB connection and the stepper motor supply provides VIO in my case. There is a "5v Only" version of the SSS TMC2100 that doesn't have this requirement, but it is not compatible with the MiniPCB or MaxPCB designs; it is however a good option for a Mega2560/RAMPS build!
- The older Pololu A4988 stepper driver module often serves as an example of how to wire one of these drivers up should you want to design/wire it yourself instead of using a RAMPS, MiniPCB, MaxPCB, etc.
- The mode control pins OnStep uses (labeled M0/M1) can be wired to CFG1/CFG2. This can select a range of settings but unfortunately those settings don't include some of the most desirable and often used modes. This is because the TMC2100 uses tri-state control logic on these pins but OnStep can only switch between LOW and HIGH (not OPEN.) If the mode you require needs CFG1 and/or CFG2 "OPEN" you will probably need to omit (or cut off) the corresponding stepper driver pin(s.) Keep in mind that OnStep can't mode switch a pin that's not connected so you often get to set one (microstep/decay) mode and stay in it!
- The Watterott drivers have extensive documentation, etc.
- Note that some FYSETC drivers seem to have silkscreening over the heatsink contact area so that might lower the thermal dissipation a little vs. the Watterott modules.