Woa. Guys it is about to hit 2021. Why are we still discussing or playing with arduino or any 8 bit controller? I mean sure they were good a decade ago or they did the job but as we chase keeping up with the average print speeds of the day and chasing the ancillary stuff like multi material printing or adding features by growing the Gcode we really should make the switch to the 32 bit boards. It is the end of 2020 and these days we do not run our stepper drivers in standalone mode and make physical adjustments with a plastic screwdriver. That is so 10 years ago. New for this decade(or not so new anymore, but still) we like to adjust forward current by making changes to marlin. We also like running the newer versions of marlin that bring specific support for these stepper drivers to be run in these UART or SPI modes. Marlin 1.1.9 does not support TMC2209, TMC2226, TMC5160, LV8729, or any other recently produced stepper driver. And to run our stepper drivers with the mainboard communicating with them is so crucial because it lets you drop out of stealthchop2 when print speeds go above a certain threshold and switch to spreadcycle for the extra torque. Also these newer drivers when communicating with the mainboard can sense their own skipped steps. This is used for the prevention of skipped steps with stallguard but also it is used for sensorless homing. And all of these features are specific to marlin 2.x and a 32 bit mainboard. And the prices on these components are so dirt cheap there is just no good reason not to upgrade. Here is a SKR mini mainboard. This board comes with a 32 bit processor and 4 built in TMC2209 drivers. For just over $20. and free shipping. You can get it with the dual mode touchscreen that doubles as a lcd12864 for $50. Right here: https://www.biqu.equipment/collectio...29366499836002