Duet Tool board for PNP head

[cncmachineguy]

This is the new thread following from here:

https://groups.google.com/g/openpnp/c/nQC_Dcefwqo

Can reprogram - Yes

PERFECT!

OMG brilliant idea to share the DIR for the C axis!!

Step can not be shared, but I think DIR can.

The 5 24V outputs can be low side switched instead of 24V output. I would need to check how the fans and heater (e3xisting 3) work now. in any event - YES

If we have available, and endstop input would be great (but honestly the stall detect works really well), the end stop just gives us another option. Maybe without it we can leave the boot switch alone?

agree on the temperature inputs

Soldering 0402 is not too bad really. I like the piggyback idea.

I am getting pretty excited about this!!

[mark maker]

> OMG brilliant idea to share the DIR for the C axis!!

Just don't.

Simultaneous, anticipatory rotation of multiple nozzles will come to OpenPnP one day!

I'm sure you'll find another unused IO.

Or add a small sub-PCB where you add an IO expander on I2C, which is fine for switching slow signals, like for valves etc. so you can dedicate the fast IOs of the MCU to the steppers.

An example I used:

https://assets.maxlinear.com/web/documents/xra1201.pdf

I even wrote an Arduino Lib:

https://github.com/markmaker/XRA1201

You could use another tiny MCU, but the expander just saves you the trouble of (initial and/or repeated) firmware programming, bug-fixing, etc.

_Mark

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[bert shivaan]

Point taken Mark, No shared DIR pin

To view this discussion on the web visit https://groups.google.com/d/msgid/openpnp/46aac01e-704b-00b6-db9a-8ef3faf5a536%40makr.zone.

[dc42]

@mark there are enough spins available to be repurposed without sharing the DIR signal or using an I2C expander. I made the suggestion because it would need one less pin, so less reworking of components. The I2C expander solution would need additional firmware support, whereas repurposing MCU pins will mostly just need changes to the configuration table and configuration constants.

@cncmachineguy the existing 3 outputs are switched to ground. OUT0 is good for about 5A and uses VIN voltage. The other two are rated at 0.8A total when fed from the on-board 12V regulator, or 2A each (limited by the JST PH connector) when the jumper is fitted to feed them from VIN.

[dc42]

PS - @cncmachineguy:

- the OUT0 pin does not have a built-in flyback diode, so if you drive a solenoid or other inductive load from it then you will need to add an external flyback diode. OUT1 and OUT2 already include flyback diodes.
- when choosing which MCU pins to reassign as STEP pins for the extra two drivers, please make sure they are on port A not port B. You can see which IO signals are connected to which pins in the schematic at https://github.com/Duet3D/Duet3-Toolboard-1LC/blob/master/Toolboard_1LC_v1.3/Duet3_TB_1LC_Schematic_v1.3.pdf and in the pin table in the firmware pin table at https://github.com/Duet3D/Duet3Expansion/blob/3.4-dev/src/Config/TOOL1LC.h.