MP6500 start-up state

When the MP6500 is started up (power-up), does it initialise the internal logic to a consistent state (in the absence of STEP pulses) - e.g. “Step” 1 on the chip data sheet? Similarly, does putting the device to Sleep, or activating Disable/Enable set the logic to a consistent state - or does it retain its previous state? I want to be sure that I can begin operation from a known starting point, and possibly to be able to reset the device later if need be.
The 6500 data sheet doesn’t give this information - it just talks about disabling the outputs.

I’m not sure if the forum is the right place for this question, or whether I should contact Pololu Support directly.


Hello, Paul.

I tested an MP6500 carrier here and this is what I found:

  • The driver always starts up in the 45 degree step angle position (as described in the datasheet’s Table 2) regardless of the microstep resolution.
  • Driving nSLEEP low disables the driver and resets the microstep position to 45 degrees.
  • Driving nENBL high disables the outputs but retains the microstep position.


Thank very much, Kevin. That’s what I need to know, and those results seem to give the most generally flexible options.

That might be useful to put in the website description for others?


Hi again Kevin.

Following your useful reply, I want back to the official MPS data sheet for the 6500, and noticed what appears to be an inconsistency there. Looking at the eighth step entry for 45º (step 5) in Table 2, it shows both phase A and B currents at + 70.71%. Then looking at Fig.5d - the eighth step waveform - it shows Step 5 with Phase A at +70.71% and Phase B at -70.71%. It isn’t until you get to step 29 (315º )that both phases are at +70.71%. A similar discrepancy occurs for Half Step, but not for Full Step or Quarter Step. So which is right?

Or am I missing something?


Hi, Paul.

It does look like the waveforms don’t match up with the table; the full and 1/4 step waveforms start with the opposite polarity compared to the 1/2 and 1/8 step ones, and A leads B in the table while B leads A in all of the waveforms (though that’s just a matter of flipping the DIR pin). I think the table matches the behavior I saw while testing, so I would be inclined to trust it more than the waveforms (the figures seem to be more of a general indication of the shape of the waveforms than an accurate representation of what the current is at each numbered microstep).

We will look at adding some info about the microstep position reset behavior to the product pages; thanks for the suggestion.


OK, that’s good to know.

For my application, the most important thing is that it always comes up the same. It’s only if things get screwy that the exact position would become important.