EasyDriver, Arduino and printer motor issue

I set up the Example 1 with EasyDriver 4.3, Arduino UNO, and 48step/rev steeper motor taken from and unavailable printer. The power source is 6 volt and 800mA max plugged to EasyDriver, motor has no load. As you see in the example, the driver is in 1/8th microstep mode. I also set delay to 5000 in the arduino code. What did I watch? The motor make the steps silently but each 8 steps, the motor buzz and that step is missed. I've change the motor and put another one from the same printer and this issue repeats. I've also change the driver and put another one from the same EasyDriver version, same story. I've turn the potentiometer in the driver, no changes.
Anyone can reproduce this and tell me what happens? This kind of motor is no suitable for this configuration? Must I use a 200step/rev motor?.

It seems to me from the Mitsumi page that 6v is much too low. I suggest you try 12v and be careful to adjust the current limit on the Easydriver to 400mA.

...R
Stepper Motor Basics
Simple Stepper Code

Robin2, I'm still searching info. I found this explanation about current ripple. The Allegro driver works in fast, slow and mixed decay (I don't understand what that specifically means) but it seems that effect appears at 200 steps/sec or higher, which is not my case. Well, I will do some other test, first your suggestions.

JoseArg:
Robin2, I'm still searching info. I found this explanation about current ripple. The Allegro driver works in fast, ...

I suspect you are over thinking the problem.

...R

JoseArg:
I set up the Example 1 with EasyDriver 4.3, Arduino UNO, and 48step/rev steeper motor taken from and unavailable printer. The power source is 6 volt and 800mA max plugged to EasyDriver, motor has no load. As you see in the example, the driver is in 1/8th microstep mode. I also set delay to 5000 in the arduino code. What did I watch? The motor make the steps silently but each 8 steps, the motor buzz and that step is missed. I've change the motor and put another one from the same printer and this issue repeats. I've also change the driver and put another one from the same EasyDriver version, same story. I've turn the potentiometer in the driver, no changes.
Anyone can reproduce this and tell me what happens? This kind of motor is no suitable for this configuration? Must I use a 200step/rev motor?.

0.8A is too low if you are only powering from 6V (which is about the minimum the EasyDriver will
work with).

Try 12 or 24V supplies at 0.8A, much more likely to work, and your motor will be able to turn at speed
rather than glacially slowly. Remember to set the EasyDrvier for 0.4A output current, of course...

Thanks both, you were right.
Now I tried with 15V and adjust the current in EasyDriver, now there no buzz (but almost inaudible one) and there's no step missing in 1/8 microstep mode. Everything looks good. Just, another comment, I can't hold my finger on the driver chip for more than 4 seconds, it's hot, is it normal?. One remedy for this could be using the sleep pin in EasyDriver?

Hot is normal.

...R

Glue a heatsink on top if you want. If the chips 100C its quite happy, your finger won't be!
Running hot does have an effect on component lifetime due to thermal cycling effects (expansion
and contraction of the device and its bonding wires inside the epoxy package). Running
cool is preferred, but sometimes you get no choice.