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DSabo
DSabo
Associate III
October 1, 2020
Solved

What is the L6474 ABS_POS register really reporting?

  • October 1, 2020
  • 2 replies
  • 912 views

I am looking at using the L6474 to drive a stepper motor. I have a question about the absolute position register (ABS_POS).

It says it is the current motor absolute position, but I want to clarify that it really is just a counter for the number of steps that have been commanded?

It initializes to 0 at power up, so it has no history, so it is really an incremental counter not an absolute. It also says it is the motor position, but it just keeps track of how many steps have been commanded, correct? There is no feedback from the motor to say if it has really taken the step or not, or if the motor was turned by something other than the motor driver, it wouldn't know, so the "motor absolute position" would be incorrect.

Is that true?

This topic has been closed for replies.
Best answer by Dario CUCCHI

Hello @DSabo​ ,

Yes, what you described is correct.

The ABS_POS register is basically a counter counting the steps after each command of step clock and direction

The L6474 has no input for positioning sensors coming from the motor (e.g. encoder feedback), so it cannot detect if the motor is moved by something else externally.

Have a good day !

2 replies

Dario CUCCHI
Dario CUCCHIBest answer
ST Employee
October 2, 2020

Hello @DSabo​ ,

Yes, what you described is correct.

The ABS_POS register is basically a counter counting the steps after each command of step clock and direction

The L6474 has no input for positioning sensors coming from the motor (e.g. encoder feedback), so it cannot detect if the motor is moved by something else externally.

Have a good day !

Cristiana SCARAMEL
Cristiana SCARAMEL
ST Employee
October 9, 2020

Hello @DSabo​ ,

I’m marking the @Dario CUCCHI​ reply as a Best Answer to make this thread easier to find for other community members, and also because I cannot mark your original post as a Best Answer since only replies can be such.

"If you feel a post has answered your question, please click ""Accept as Solution"""
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