Driver pulse duration setting location?

I am using Arduino mega/Ramps 1.4/Marlin and am going to give the DRV8825 drivers a shot in place of the 4988's. Info on the 8825 via Pololus site reads- "The timing requirements for minimum pulse durations on the STEP pin are different for the two drivers. With the DRV8825, the high and low STEP pulses must each be at least 1.9 us; they can be as short as 1 us when using the A4988.". I m not having any luck locating this setting in Marlin. Anyone know?

Quote
Bill Clark
I am using Arduino mega/Ramps 1.4/Marlin and am going to give the DRV8825 drivers a shot in place of the 4988's. Info on the 8825 via Pololus site reads- "The timing requirements for minimum pulse durations on the STEP pin are different for the two drivers. With the DRV8825, the high and low STEP pulses must each be at least 1.9 us; they can be as short as 1 us when using the A4988.". I m not having any luck locating this setting in Marlin. Anyone know?

there isn't actually a setting for it, if you have a poke around stepper.cpp there is a spot that can be modified to put in a small pause so you can make the steps longer,

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You don't have to change the timing to run the DRV8825 with an Arduino Mega only steps/unit are twice as much now.
-Olaf

Thanks guys. It is running great on the 8825's w/o any attempts to tinker with pulse timing

Edited 1 time(s). Last edit at 12/25/2015 12:55PM by Bill Clark.