@D300VS_duet3d And when you connect the USB, if you touch the processor with your finger, it becomes hot? If so, your Board is dead, you need to change the processor.

@Danal
Diodes have nothing to do with it, I even gave a link to the implementation, and explain how to do it no one can or does not want to, although this question has been raised since 2016.... I'm sorry, but terrible support for the project.

Hmm, there was already an attempt to implement brake control. Stepper brake feature #220
Only who will explain, entered it in the firmware and how to use it, configure?

In MARLIN found such a function, and in RRF there is something similar with FAN?

* The fan will turn on automatically whenever any stepper is enabled
* and turn off after a set period after all steppers are turned off.
#define USE_CONTROLLER_FAN
#if ENABLED(USE_CONTROLLER_FAN)
#define CONTROLLER_FAN_PIN 6 // Set a custom pin for the controller fan
#define CONTROLLERFAN_SECS 1 // Duration in seconds for the fan to run after all motors are disabled
#define CONTROLLERFAN_SPEED 255 // 255 == full speed
#endif

I think it will suit me.

@D300VS_duet3d And when you connect the USB, if you touch the processor with your finger, it becomes hot? If so, your Board is dead, you need to change the processor.

@bearer I understand you.
But, then again the same question, how to control the PWM signal? I understand that you can release one of the unused heaters, as with BLTOUCH, but what to write in the configuration so that it gives a logical 1 when you start using the driver, and a logical 0 when you turn off, or set.

As I understand it, there is no solution at the moment?

It would be better to switch the relay on a little before the enable command is sent, and turn it off a little after the drive is disabled.

I'm just getting to know the RRF. So I do not know how it can be implemented. Please tell me how to do it?

Thank you, but according to the scheme pin ENN is common to all drivers and when you turn on the control wire of the relay, pin 28, the relay is turned on, but the motors are not active at this time, which leads to a sharp lowering of the table. Maybe you can assign a separate pin, so that when the z-axis driver is activated, it turns on the relay, and when it is inactive, it turns off?

Good afternoon. I want to put Duet 2 wi fi, but there was a question. I have a belt in place of the screw on the z axis and used a relay for braking. Diagram:
How can I connect the relay to the TMC2660 drivers? Thanks for the answers.