Duet 3 mini Expansion

Proschi3D

Is it possible to expand the IO inputs on the Duet 3 mini?
I have all but one occupied and would like to control two more rc servos.
Otherwise I would have to home the Y axis sensorless to get an input free

cosmowave

@Proschi78 Perhaps with a toolboard?

dc42

@Proschi78 if you are not using a temperature daughter board, you can use the two CS pins on the connector as additional inputs or non-PWM outputs. Be careful because there is no protection on those pins.

Proschi3D

@dc42 thanks I will try it on the CS pins

Proschi3D

@Proschi78
ok i have now connected the servo to spi2.cs1.

;Servo configuration
M950 S1 C"spi2.cs1" ; assign GPIO port 1 to out9 (Servo header), servo mode

what command do i use to move it now?

M280 P# S80 ?

dc42

@Proschi78 you asked about expanding the IO inputs. To control a servo, you need an output, and it must be PWM-capable. The SPI CS pins can be used as low-current outputs, but they are not PWM-capable.

Do you have any of the four low-current outputs free? They can be used to drive servos, in conjunction with an external pullup resistor. Connect the OUTn_NEG pin of the output to the servo control wire, and connect a resistor in the range 2K to 10K between that connection and +5V. You will need to get +5V and GND for the servo from a different connector. Be careful not to connect the servo to the VFAN [in of the OUT connector by mistake.

Proschi3D

@dc42 ok then i could put a filament sensor or limit switch on a cs in right?

dc42

@Proschi78 said in Duet 3 mini Expansion:

@dc42 ok then i could put a filament sensor or limit switch on a cs in right?

Yes.

It's OK to use the input and output pin of an IO connector for different purposes, for example to drive a hobby servo and read and endstop.

Proschi3D

@dc42 OK thank you
then I will solve it like this