How to change the Current using Vref
It is very hard to read the current being fed to stepper motors. To determine that current we rely on the Vref value. The Vref value is a voltage reference measured in VDC that can be read using a multimeter. It helps us setting the current output of the stepper motor driver.
Different 3D printer mainboards use different stepper motor drivers. Each type of stepper motor drivers has its own formula to calculate the required Vref to get a specific current. Here are some examples:
- TMC stepper drivers.
The formula for these drivers is Vref = ( I * 2.5 ) / Imax
Where I is the target current value measured in A; and Imax is 1.77 on regular mode and 1.2 on SilentStepSticks mode. - Pololu A4998.
The formula for these drivers is Vref = I * 8 * R
Where I is the target current value measured in A; and R is the Sense Resistor value, that depends on what board are you using. Melzis use 0.1,the Creality Silent boards use 0.15, ...
Example: Desire current 0.5a will result in 0.6 VREF on Creality A4998 Board
0.5 * 8 * 0.15=0.6
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