About the “sense resistor” value, namely “`R_SENSE`.”

[issuefiler]

inline constexpr float sense_resistor_value = 0.11F;
inline constexpr std::uint8_t uart_slave_address = 0b00;

TMC2209Stepper driver {&Serial1, sense_resistor_value, uart_slave_address};

When I used the teemuatlut/TMCStepper library, I needed a value called R_SENSE to construct a TMC2209Stepper instance. I set it with the common value 0.11F without actually understanding what that means and what that does.

Using this library, janelia-arduino/TMC2209, I’ve noticed that the TMC2209 constructor doesn’t require the R_SENSE value, unlike the TMC2209Stepper.

I wonder why. How is the value used in the teemuatlut/TMCStepper library and why is it not used in the janelia-arduino/TMC2209 library? Is it unnecessary? What does that value mean and do?

[peterpolidoro]

The sense resistor value is probably an input to that library so that motor current can be set using units of amps or milliamps rather than simply a register value or percentage of maximum current.

I have been thinking of implementing a similar function in this library, but I need to understand all of the details of how that would work exactly before adding it.

[issuefiler]

Yes, so I noticed. I’ve been reading their code and Trinamic’s datasheet thoroughly and I’ve seen their rms_current method calculating the most efficient IRUN, IHOLD, and vsense values out of the R_SENSE value and the given amperage.

Closing this issue, as it’s a duplicate of the issue #28.