Hello, I need some help. How do I set the current limit in my A4988 driver for my Nema17 stepper motor? I saw a formula (Vref = Imot * 8 * Rs) that requires the current sensing resistor to get the Vref, but my driver's datasheet doesn't have the current sensing resistor value. My stepper motor has a…

Post a close up, focused picture of the motor driver, and forum members should be able to identify and tell you the value of the current sense resistors. The A4988 can't deliver more than 1 A/winding without overheating, so set the current limit to that or lower.

[345164297_234261069330403_1307857118359595364_n] Here sir. I searched about how to determine the current sensing resistor of the A4988 and one of them says that I should read the value on top of the resistor, which in my A4988, it is R100. Does it mean that the current sensing resistor of my driv…

Instructions for setting current limits on stepper drivers. [image] Newbie1.1.1: Does it mean that the current sensing resistor of my driver is 100mΩ or 0.1Ω ?? Correct me if I'm wrong. You are correct. R100 means 0.1 Ohms which is the usual value for cloned Chinese A4988 stepper drivers.

My stepper motor has a rated current of 1.68A. So using the formula Vref = Imot * 8 * Rs Imot = Rated current of stepper motor Rs = current sensing resistor Vref = 1.68A * 8 * 0.1 ohm Vref = 1.34V So I will set my current limit on my driver to 1.34V? Correct me if I'm wrong.

It's a little more complicated that that. In full step mode, that formula actually sets the current per coil to be 0.707 x Imot. If you want to set the coil currents to 1.68, then Imot should = 1.68 x 1.414. However, if 1.68 for Imot provides enough torque for your project then it will make the m…

Where did the 0.707 and 1.414 come from sir? Is my formula wrong? Based on the reference and youtube that I watched, they used the formula (Vref = Imot * 8 * Rs) to determine the Vref value to set up on the A4988. And they get the value of Imot based on the rated current of the stepper motor that t…

This webpage explains: [image] Pololu - A4988 Stepper Motor Driver Carrier This breakout board for Allegro’s A4988 microstepping bipolar stepper motor driver features adjustable current limiting, over-current and over-temperature protection, and five different microstep resolutions (down…

[image] Newbie1.1.1: So I will set my current limit on my driver to 1.34V? No, because the A4988 cannot deliver 1.68 Amperes. Set Vref for 0.8V.

How did you get the 0.8V ? Please enlighten me.

Enlightenment follows: [image] Newbie1.1.1: Vref = 1.00A * 8 * 0.1 ohm Please take the time to read and absorb the responses to your posts. This is a technical forum.

Setting up current limit in A4988 for Nema17 stepper motor

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jim-p June 2, 2023, 1:21pm 8

This webpage explains:

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Setting up current limit in A4988 for Nema17 stepper motor

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