About L297 stepper controller cw/ccw switching

Go To Last Post
4 posts / 0 new
Author
Message
#1
  • 1
  • 2
  • 3
  • 4
  • 5
Total votes: 0


What happens if I change from CW to CCW when Clk is high. Will the signals A, B, C, D immediately change to the previous step state? Or doe this only happen after the clock goes from low to high?
Documentation says that "synchronisation is internally and change can therefore be done at anytime".
Can A, B, C, D (never?) change if Clk is high?

  • 1
  • 2
  • 3
  • 4
  • 5
Total votes: 0

Well it is said in that picture and in datasheet. It steps on the rising edge of the CLOCK. The CW/CCW pin needs to be stable for some time before rising CLOCK edge, and needs to be stable some time after rising CLOCK edge. You need to look these times from the datasheet, it might be on the same page.

  • 1
  • 2
  • 3
  • 4
  • 5
Total votes: 0

So it does NOT step (or change A, B, C, D) if I change CC/CCW when Clk stays high?

My understanding is that the discripition does not exclude the possibility that signal A changes when I change from CW to CCW during the high time of ClkPulse 3. It could go immediately back to the situation of the high state ClkPulse 2.

  • 1
  • 2
  • 3
  • 4
  • 5
Total votes: 0

OK, I think this diagram explains it.
CW/CCW is ClockedIn in by the FlipFlop FF3 at the moment CLK goes low.
So A, B, C, D can never change when the clock is high.

Correct?