Controlling RC Servos with the expansion board

mcole

One other thing, I think the pin out's for Heater 6 PCM are wrong - I'm getting +5v on the middle pin and GND on the pin closest to the E2 connector.

Almost fried a servo.

dc42

The tab by the Ethernet port is for connecting shielding only. It is not connected to the board ground.

T3P3Tony

@mcole:

One other thing, I think the pin out's for Heater 6 PCM are wrong - I'm getting +5v on the middle pin and GND on the pin closest to the E2 connector.

Almost fried a servo.

I just checked a expansion breakout board and that pin out appears correct - ground on the pin closed E2, 5V on the middle, control on the pin closest the 50 way connector. Looking at the silkscreen that is what it is labelled as. Is your board silkscreen different?

mcole

Hopefully the attached image shows everything - I tried to fit everything relevant in.

19v on power in to my Duet Ethernet

Plug wired according to Duet expansion header wiki image (https://www.duet3d.com/wiki/File:ExpBreakoutv1.0_wiring.png)

The DVM is showing -4.87 volts. If I swap the red and black leads on the Heater 6 PWM I get +4.87 volts.

dc42

That's correct, +5V is on the centre pin. What makes you think it is incorrect? Perhaps you are using an Airtronics servo, which has the + and - connections swapped compared to everyone else, see https://www.princeton.edu/~mae412/TEXT/NTRAK2002/292-302.pdf.

mcole

The image on the wiki shows the center pin being GND and the end pin being 5v+

dc42

@mcole:

The image on the wiki shows the center pin being GND and the end pin being 5v+

Which wiki page is that? Please provide a link.

mcole

@dc42:

Which wiki page is that? Please provide a link.

Here you go - https://www.duet3d.com/wiki/File:ExpBreakoutv1.0_wiring.png (please confirm so I know I'm not going mad)

dc42

Thanks, I'll get it corrected.

mcole

Thank you.

For anyone else interested in adding a servo (such as a Futaba for tool change) the 3 pin heater headers work. Details are in the wiki, but I know searching in the forum is the first place I turn to sometimes. Attach the servo so the red wire is +5v, black wire is GND, and the white wire connects to PWM.

Disable the heater control using

M307 H6 A-1 C-1 D-1
```(where H6 corresponds to the heater header being used) This can be in config.g

You can then control the servo using the following g code

M280 P6 S1

T3P3Tony

I have corrected the wiki page, really sorry that slipped through. you must be the first person to read the documentation!
https://duet3d.com/wiki/Expansion_breakout_board

https://duet3d.com/wiki/File:ExpBreakoutv1.1_wiring.png

mcole

@T3P3Tony:

I have corrected the wiki page, really sorry that slipped through. you must be the first person to read the documentation!

I need all the help I can get! I'm a ME, not an EE.

Thank you though, I'm constantly impressed by how good a job you and DC do with keeping us all happy.