Re: Stepper Adjustment and PEC

Dan Walker

Hi All,


Still having problems with the focus motors on MaxESP3.


I had some time today to test a4988 drivers in place of the TMC2208’s. Still not a peep from the steppers.


I checked and rechecked all the hardware.


VM2 is 12V as planned, so Vmot is OK.

All connections from ESP to the drivers are OK.

Tested a range of Vref.


The only thing I can see that is odd... the RA/DEC drivers (TMC5160) have 12V, the same as their respective Vmot, on their 1A, 1B, 2A, 2B pins.


The focus motors have just 3.8V on their 1A, 1B... pins. Not sure if that is important or how that voltage is determined.


So bottom line is, despite an extensive search, can’t find anything obviously wrong hardware wise.


Motors were tested and seem fine (can generate a voltage when spinning shaft).


Software is set up like this for both focus axis:



// see

#define FOCUSER1                      ON //    OFF, ON to enable this focuser.                                               Option

#define AXIS4_STEPS_PER_MICRON        0.5 //    0.5, n. Steps per micrometer. Figure this out by testing or other means.      Adjust

#define AXIS4_STEP_RATE_MAX           8.0 //    8.0, n, (millisec.) Min. ms/step depends on processor. In DC mode, PWM freq.  Adjust


#define AXIS4_DRIVER_MODEL            OFF //    OFF, TMC2130, TMC5160. Leave OFF for all drivers models except these.         Option

#define AXIS4_DRIVER_MICROSTEPS       OFF //    OFF, n. Microstep mode when tracking.                   For TMC2130, TMC5160. Option

#define AXIS4_DRIVER_IHOLD            OFF //    OFF, n, (mA.) Current standstill. OFF uses IRUN/2.0.                  "       Option

#define AXIS4_DRIVER_IRUN             OFF //    OFF, n, (mA.) Current tracking, appropriate for stepper/driver/etc.   "       Option

#define AXIS4_DRIVER_POWER_DOWN       OFF //    OFF, ON Powers off the motor at stand-still.                                  Option

#define AXIS4_DRIVER_REVERSE          OFF //    OFF, ON Reverses movement direction, or reverse wiring instead to correct.    Option

#define AXIS4_DRIVER_DC_MODE          OFF //    OFF, DRV8825 for pwm dc motor control on stepper driver outputs.              Option


#define AXIS4_LIMIT_MIN_RATE           10 //     10, n. Where n=1..1000 (um/s.) Minimum microns/second. In DC mode, min pwr.  Adjust

#define AXIS4_LIMIT_MIN                 0 //      0, n. Where n=0..500 (millimeters.) Minimum allowed position.               Adjust

#define AXIS4_LIMIT_MAX                50 //     50, n. Where n=0..500 (millimeters.) Maximum allowed position.               Adjust


Any more ideas are gratefully received!







Sent from Mail for Windows 10


From: Howard Dutton
Sent: 09 October 2020 20:23
Subject: Re: [onstep] Stepper Adjustment and PEC



On Fri, Oct 9, 2020 at 12:05 PM, Khalid Baheyeldin wrote:

But I don't know offhand how the MaxPCB is wired, and whether jumpers are used for microstepping.

Jumpers are used to set micro-stepping M0, M1, M2 (or whatever else the particular stepper driver calls them.)
The EN pin is electrically disconnected normally, but there is an option to control it on Axis3.  Every other stepstick driver I know of is enabled by default under this condition.
The SLP/RST (or whatever else the particular stepper driver calls them) are tied together, this is a common socket design.

I know of no reason that TMC2208 wouldn't work.


Join to automatically receive all group messages.