Modifications

Afin d'atteindre des vitesses plus élevées (de plus hau-débit de pas), il faut typiquement utiliser une tension d'alimentation moteur plus élevée, ce qui ne serait pas possible sans électronique de limitation active de courant.  

Afin d'atteindre des vitesses plus élevées (de plus hau-débit de pas), il faut typiquement utiliser une tension d'alimentation moteur plus élevée, ce qui ne serait pas possible sans électronique de limitation active de courant.  

For instance, a typical stepper motor might have a maximum current rating of 1 A with a 5Ω coil resistance, which would indicate a maximum motor supply of 5 V. Using such a motor with 12 V would allow higher step rates, but the current must actively be limited to under 1 A to prevent damage to the motor.

Prenons par exemple un moteur prévu pour supporter 1 Ampère avec une résistance de bobine de 5Ω, cela indiquant que la tension maximale de l'alimentation moteur est de 5 Volts (U=RxI; u=5 Ohms x 1 Amp). Utiliser un tel moteur avec un tension de 12 V permettrait d'atteindre une plus haut débit de pas mais le courant doit absolument être limité à 1Amp (de façon active) sinon le moteur sera rapidement endommagé.

The DRV8825 supports such active current limiting, and the trimmer potentiometer on the board can be used to set the current limit. You will typically want to set the driver’s current limit to be at or below the current rating of your stepper motor. One way to set the current limit is to put the driver into full-step mode and to measure the current running through a single motor coil without clocking the STEP input. The measured current will be 0.7 times the current limit (since both coils are always on and limited to approximately 70% of the current limit setting in full-step mode).

The DRV8825 supports such active current limiting, and the trimmer potentiometer on the board can be used to set the current limit. You will typically want to set the driver’s current limit to be at or below the current rating of your stepper motor. One way to set the current limit is to put the driver into full-step mode and to measure the current running through a single motor coil without clocking the STEP input. The measured current will be 0.7 times the current limit (since both coils are always on and limited to approximately 70% of the current limit setting in full-step mode).

  Current Limit = VREF × 2

  Current Limit = VREF × 2

 

So, for example, if you have a stepper motor rated for 1 A, you can set the current limit to 1 A by setting the reference voltage to 0.5 V.

So, for example, if you have a stepper motor rated for 1 A, you can set the current limit to 1 A by setting the reference voltage to 0.5 V.