Geeetech

I find same problem with DRV8825.

At first I find problem that my M201 "lost step" in Y-Axis (using standard A4988 driver).
To solve this one I try:
1) change slicer settings (reduce movment speed and reduce acceleration)
2) increase step motor driver current limit
3) change step motor for more powerfull
4) Update firmware to 1.0.5
Any one don't solve problem and in finish of all this tries I break A4988 driver.
At hand I have DRV8825 which I use in other CNC+arduino and find problem that this driver don't work in GTM32 at home commad.
But manual move work well.

Solution of problem must find in GTM32 firmware v1.0.4 and still not solved in v1.0.5.

Main problem in how GTM32 firmware execute G28 command (move home).
When GTM32 execute G28 command STEP pulse witdh for driver IC's is about 0.4us - this is not enought for correct work both step driver (A4988 and DRV8825).
Look attachted STEP pulse width oscillogram when GTM32 execute G28 command: Accordingly to IC's specification:
- A4988 - min STEP pulse width must be 1 us at least
- DRV8825 - min STEP pulse width is 1.9 us

When GTM32 execute command G0/G1 or make Manual movement from main menu pulse with is about 2.4 us - this is enought for well work both driver A4988 and DRV8825
Look oscillogram when make Manual movment: Same one for G0 and G1 command.
2.4 us time is more then specified 1us for A4988 and 1.9us for DRV8825 - as result both driver work well when exucute G0/G1 commands

Dear Geeetech - please make firmware update

1) for solving pulse width problem for G28 command

2) increase STEP pulse width for 3us for all commands (G28, G0, G1)
I think 50% over min cpecified values will be greate for stable work GTM32 with both driver A4988 and DRV8825
Also I think this allow solve step lost problem and use other driver IC's

3) Will be greate if you make ability users to set PULSE width time
- manually via main menu
- or via G-code like http://reprap.org/wiki/G-code#M569:_Set ... ble_values

Hope on support

For the moment I have solved it for me by replacing the X & Y Steppers with 0.9° Steppers from ebay 15.5€ ant that works after adapting the steps/mm perfectly.
But still hope we can use DRV8825 with a corrected firmware - that would be great and would double the steps/mm again.

Unfortunately there is no source and not a real support for the GTM32 and M201 combination - so I cannot recommend this combination to friends at the moment.

To overcome the problem and to increase the number of steps/mm further I exchanged now the 20 tooth pulley on X & Y axis with a 16 tooth pulley.
This gives me in combination with the 0.9° steppers 200 steps/mm (198 after calibration).

But I still hope we either get the source for the M201/GTM32 combination or I replace the GTM32 with a RAMPS1.4/Arduino and using DRV8825 which than will give me theoretical fantastic 400 steps/mm => 0.0025 mm/step.

Also other problems still not sufficiently solved - so when I get time in the next view weeks I will do my own stuff as mentioned above - I think mixing is not a big magic and with some trial I may find a solution to run it on another platform .
Firmware Version 1.05 is still not working as it should.

hello
still no anwser for the homming problem.

is there any develope or is that new update firmware DEAD?

Thanks

Some news ? or geeetech has a very bad support !