Setup:
Arduino Uno R4 Minima
Stepper Motor - Stepperonline E Series Nema 17
Generic A4988 Driver
6AA Batteries in series (checked with multimeter, they provide a steady 9.5V)
Deceptively simple issue: I built the circuit seen above based on a couple guides I found about running stepper motors using an arduino and driver, adjusted the vref so the motor would run at ~80% of it's max current draw, used some basic example code from this guide, and my motor vibrates back and forth without actually going anywhere. I also tried using the example code from this post, but to no avail. Every part of the circuit I can think to check with the multimeter appears to be working fine, and I've rearranged the stepper motor wires just about every possible way without getting a different result. I did check the resistance between the motor wires and found that the two windings are connected to the black/blue wires and the red/green wires respectively (both pairs have ~3Ohms resistance between them). Also tried switching drivers and switching motors, as I have multiple of both.
I've looked at as many videos and forum posts as I could find and still nothing has resolved this issue, so any assistance would be amazing!
Both the motor driver and the motor power supply are inadequate for that motor, and that current setting. 0.8*1.5A = 1.2A.
The A4988 can't deliver more than 1A/winding before it heats up and shuts down, and 6xAA are inadequate to deliver 2.4A for a significant length of time.
You cannot measure with a multimeter if this is really stable all the time. There may be short voltage drops. You are near the limit af the A4988, as it needs at least 8V Vmot. More is better - it should be at least 12V.
Furthermore I don't see see the needed capacitor of at least 47µF ( more is better) close to the Vmot and Gnd pin of the A4988.
The project I'm working on doesn't require that the motor is powered for very long or that the motor delivers very much torque, so I was under the impression (per this thread) that running the motor at that lower current setting would still allow it to turn, just with lower torque. Should I move up to the Polulu driver? That seems to be the most common recommendation for undercurrent issues like this.
Are there driver/motor combinations which could run off 6AA's? I'm limited in what power source I can use for this, while the motors and drivers I use are flexible. The capacitor you mentioned was present on some of the wiring diagrams I could find online, but others didn't show it, so I was unsure whether it was fully necessary or just a nice-to-have.
This capacitor is mandatory. This capacitor, the driver and the motor coils together work as a sort of buck converter. All Elements are needed to work properly.
The A4988 driver is shurly not your main problem - even if it's operated near its limits. Does the heat sink get hot?
Maybe your type of AA batteries don't have enough current do you have another power supply to try? Connect 220uF on Vmot/GND pins near the driver.
Btw, In the driver datasheet 8V is the minimum operating voltage, but when I was making robot with A4988 and Nema 17, it worked good down to 6.5V for motors power supply.
I have access to a variable power supply during the week to see what kind of current draw I'm getting, but I'm using ordinary energizer batteries which should be able to supply up to 3A (although not for long, as they're typically only rated for ~3000mAh).
Appreciate the tip about adding a cap, I've got some coming in tomorrow that have a range of capacitances I can try.
Tried adding a 47uF and 220uF capacitor in the way this graphic from polulu shows (in parallel with the voltage source). Also used a variable power supply to output a constant 10V to the motor. While I could see the current spike whenever the motor tried to run (I saw peaks of ~1.45A), the motor didn't even vibrate this time around, there was just a small click every time it attempted to move. The click was too low pitch to be audible, but I could feel it happen (felt similar to the haptic feedback from an iphone). The click was less intense when I had the 47uF cap in the circuit vs the 220uF, but the current draw was the same for both.
Did you try the 'simple stepper' programm @groundFungus recommended in post #3?
If this does not run either, the problem is the HW, if it works, the problem is within your sketch which you still don't show.