I am using this https://github.com/watterott/SilentStepStick stepper driver to drive a stepper motor. I am having trouble setting pins to HI-Z/floating to configure the stepper driver.
To set the driver to 16 micro steps and full interpolation, one has to set 2 configuration pins to HI-Z/floating (datasheet, p.9). The example code on github (TMC2100.ino) just doesn't touch the pins at all, this works fine for me.
However, if I only add the lines:
pinMode(11, INPUT); //connected to CFG1 pinMode(10, INPUT); //connected to CFG2
which should set the pins to HI-Z/floating, the result is different. The motor turns at the same speed, but makes more noise, I believe the driver is using the 16 step method with no interpolation. This corresponds to both pins being interpreted as high.
This makes me believe, that the Arduino uses a different code at startup than being used in
pinMode(x, INPUT) to configure all pins. I am using a Teensy 3.1/3.2.
How can I solve the problem? Pins 11 and 10 are hard wired to the driver, as it replaced the well known A984. Apart from the obvious "don't configure the pins then", I would like to know what's going on here.