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Micro-stepping the DRV8823-Q1

Philip Ashmore
Prodigy 150 points
Other Parts Discussed in Thread: DRV8823-Q1, DRV8823EVM, DRV8823

Searching for "microstepping" in the DRV8823-Q1 (Rev B) document version "SLVSBH2B – JUNE 2012 – REVISED JANUARY 2013" yields just one result - "eight current levels (set through the serial interface) allow microstepping with bipolar stepper motors".

It's not clear if it's even possible for current to flow through both bridges at the same time - a basic requirement for micro-stepping.

There is a mention of the current control capability to turn off the current once a limit has been reached.

So is it possible to start another phase before the current limit is reached in the previous phase, allowing current to flow through both bridges?

This looks a bit clumsy to me, am I missing a better way of doing this?

  • 0
    TI__Guru** 114905 points

    Hi Philip,

    The DRV8823-Q1 can perform microstepping of two steppers. To do so requires controlling xPH/xEN/xI signals via the serial interface. The xPH/xEN/xI signals control the direction, enabling, and amount of current in each winding.

    The DRV8823-Q1 will allow current to flow both bridges.

    The DRV8823EVM is available to allow evaluation of the DRV8823. Also schematics and microcontroller firmware are available online. The software controls brushed motors.

    Please see application note (LINK) for an example of how to perform microstepping.

  • 0 in reply to Rick Duncan
    Prodigy 150 points
    My bad! Maybe there could be some more detail about this in the document.
    My mistake was in thinking that PHASE controlled which bridge was on, which is true, but there are two bridges for each output, and two outputs for each stepper! D'oh.