how to know QEP(encoder absolute count )

Dave Hunson

Hi every one 1

I am using proj_lab13b.c ,I want to have absolute motor count either in MRev or Encoder pulse .

I found ST_Obj->Pos->move->PosRollover and ST_Obj->Pos->move->PosRef_mrev which is so hard to convert them in to absolute Mrev or Encouder counts

do you know any register to show absolute position in encoder count or Mrev?

regards.

Dave

over 6 years ago

0 Yanming Luo over 6 years ago

TI__Guru** 115470 points

There are no such variables to support your requirement in instaSPIN-motion, you have to calculate the absolute position based on the PosStepInt_mrev and PosStepFrac_mrev since the position sensor is an incremental encoder, not an absolute encoder supported here.

0 Dave Hunson over 6 years ago in reply to Yanming Luo

Expert 1740 points

i mean the register which store the counts ,I want that do you know which register is?

0 Yanming Luo over 6 years ago in reply to Dave Hunson

TI__Guru** 115470 points

As you see in the datasheet of this device or HAL_getQepPosnCounts() in hal.h, the QPOSCNT register shows the current position count from QEP for the encoder, but it's an incremental count, especially there are multi turns rotation, so you need to know the trigger event from index also.

0 Dave Hunson over 6 years ago in reply to Yanming Luo

Expert 1740 points

Thanks dear .
so i know QPOSCNT is the register of counter Encoder
So,what is the register of index Counter?

regards
Dave

0 Yanming Luo over 6 years ago in reply to Dave Hunson

TI__Guru** 115470 points

It's QFLG which just shows an index event latch, not any register to show how many index events appear.

You might have a look at the TRM of the device that should have a more detailed description of the QEP registers.
www.ti.com/.../spruh18g.pdf

0 Yanming Luo over 6 years ago in reply to Yanming Luo

TI__Guru** 115470 points

It's been a week since we heard from you, so I am assuming you no longer need clarification for your question that will be marking this thread as closed. You can reply with a post or create a new thread if you have any further question on this topic. Thanks.

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how to know QEP(encoder absolute count )