I've not tried it, but it should be possible to use this stepper driver.
The pulse (step), direction, and enable signals can be connected to the ATMega/Arduino directly. The following connections should work:
Connect the following TB6600 pins to the following nets in the AstroEQ ATMega162 or Arduino Mega schematics.
- "Pulse-" -> "Step"
- "En+" -> "En"
- "Dir-" -> "Dir"
- "Pulse+" -> +5V
- "Dir+" -> +5V
- "En-" -> GND
In the AstroEQ configuration utility, select the DRV8825 option from the dropdown, and set the microstep level as per the settings you selected on the TB6600 DIP switches, and ensure the "uStep Gear Changing" option is set to disabled.