Disabling Axis

[rojhan]

I'm going reconnect ENA+ to 5V and ENA- to the output pin and pull the output pin low with a resistor. With no inputs this should disable the drivers (ENA+ at 5V, ENA- pulled to ground).

Here's what the DM556T manual says:

[...]

To clarify how it operates, I would completely disconnect the driver from the C11G, then manually put +5v on the DM556T ENA+ terminal, and ground on the ENA- terminal. If the stepper engages then you know +5v on ENA+ is an enabling, not disabling, condition. Then force both ENA+ and ENA- to ground, and that should disable the driver. Remove all connections from ENA+ and ENA- and that should enable the driver again.

The manual is a bit ambiguous on this. However, it shows that the step/dir/enable inputs all go through optocouplers and says that with no voltage applied that the drivers are enabled. Therefore, a relative high on ENA+ is needed to disable. This has been proven many times over.

The solution is to leave ENA- connected directly to ground, and use one of the C11G relays to drive the ENA+ terminal. Connect the relay common to ENA+, connect the relay NC terminal to ground, and the relay NO terminal to +5v. Then configure the axis Enable pin/port to whichever pin/port drives the relay.

In that configuration, both ENA+ and ENA- will be connected to ground at startup, and the DM556T should disengage the stepper. It should only engage the stepper when the relay control pin is asserted, and only if the charge pump is running.

There are no free relays. That's a piece that's unclear in the C11G specs. There is only one directly controllable relay and that goes to the water pump for cooling. The other two relays are dedicated to the spindle and are indirectly controlled by PWM and direction.

P.S. -- Stop pulling pins to +5v or ground. You're likely to create more problems that could blow up your driver or C11G.

I don't *want* to use pullup/pulldown, but that is the current state I'm in with the interaction between the components. But, there is no possibility of damage (other than bad wiring) to TTL if the properly sized resistors are used other than an input/output being stuck in an undesired state.... Which is exactly the problem I have now with how UCCNC manages axis disable and how that interacts with the other components.

[rojhan]

This is now operating as desired, in a deterministic manner.

Until UCCNC is running, the reset button is inactive, and the charge pump output is enabled; the steppers, spindle, and water pump are all forced to disabled.

Additionally, until the axis is configured as enabled, and the enable pin active (high); the axes remain disabled. The A-Axis is controlled by a separate enable pin from XYZ so I can safely remove the rotary when not in use.

As a side effect, the charge pump enable can now feed a daughter C10 BOB.

- C11G charge pump mode enabled.
- UCCNC charge pump output enabled.
- Stepper driver ENA+ to 5V
- Stepper driver ENA- to output pin
- Output pin pulled down to ground with 680ohm resistor. The stepper driver requires at least 7ma to reliably activate the optoisolator and disable the driver. 5V/680ohm=7.3ma. This is the weakest pulldown I can create and meet spec.

I would still like the option of configuring UCCNC to set the enable pin to a specific or inverted enable state if the axis is disabled.