Problems with 16x microstepping

I am having a problem with 16x microstepping on a RAMPS 1.4 board. All jumpers are set to 16x but the motors seem to only be capable of 8x microstepping.

I have checked the firmware and done a sanity check by writing a little program to pulse the motor for 1 rev. It takes only 1600 (200x8) to complete a revolution.

Motors are Nema 17 SY42STH47-1684B (200 steps per rev) running Pololu Drivers.

Any ideas what could be happening?

There was another thread here a few weeks ago which suggests ther are others who have this issue. Could it be a board error?

Previous thread

Are they genuine Pololus? Which chip do they have on them?

---

[www.hydraraptor.blogspot.com]

Ah yes I think that is the issue. They use A4984 chips which only support 8th step. Perhaps they differ from the A4983. This may also explain why my electronics run cold. I think they handle higher current. I will have to compare the specifications.

Are they stepsticks rather than Pololus? In which case the VREF current calculation is different and for the same pot position the current is less.

---

[www.hydraraptor.blogspot.com]