cannot power duet 6hc from sbc



  • i removed jumpers 'Internal 5V En' and '5V -> SBC'. then i installed jumper SBC -> 5V*. subsequently i connected the SBC (raspberry 4) to it's power supply and powered it up. now i can ssh the raspberry but i cannot connect to duet's web interface (HTTP ERROR 500) and the 5V-led on the duet is off which makes me think that the duet is not 5V-pwered form the SBC.

    what did i miss?

    hw: duet 3 6hc rev 1.0, sw 3.0rc2



  • https://duet3d.dozuki.com/Wiki/Duet_3_Mainboard_6HC_Hardware_Overview

    In normal operation the internal 5V is enabled and the SBC is powered by the Duet's 5V. Alternatively the protection can be bypassed and the SBC can provide 5V for the Duet using the "SBC -> 5V" jumper. In this case the 5V->SBC and the SBC->5V* jumpers are both fitted



  • https://duet3d.dozuki.com/Wiki/Duet_3_Mainboard_6HC_Wiring_Diagram#Section_Description_of_Connections states:

    The default 5V power configuration is Internal 5V enable - jumpered, 5V->SBC jumpered (the Duet is powering the SBC) , SBC->5V* not jumpered. If you want the SBC to provide 5V to the Duet then remove the jumper from 5V->SBC and from Internal 5v En. Place a jumper on SBC-5V*. NOTE this bypasses the 5V protection and a fault on the SBC may damage the Duet. <<

    which is inconsistent with

    In normal operation the internal 5V is enabled and the SBC is powered by the Duet's 5V. Alternatively the protection can be bypassed and the SBC can provide 5V for the Duet using the "SBC -> 5V" jumper. In this case the 5V->SBC and the SBC->5V* jumpers are both fitted. <<

    going to give the later a try.



  • @Danal i tried it - the effect was that the 5V and the 3.3V leds are now on (not very shiny though) but 'HTTP ERROR 500' persists if i want to connect to the board via the web interface implemented in the sbc. maybe the raspberry psu is too weak (it is rated 5.1v 3.0A) for powering the duet. the raspberry is working. at least i can login using ssh.

    background: i wish to be able to remotely switch the printer on and off via the pson pin.

    btw: currently i feel it would not be the worst idea to use octoprint to control my printer.



  • Hmmm... I haven't tried this, I'm just going by the doc. Which is, as you point out, inconsistent.

    Anyway, for the moment, perhaps set it up where Duet powers Pi, and do some further setup and learning. You can switch the power the way you want it later.



  • @Danal

    If you want the SBC to provide 5V to the Duet then remove the jumper from 5V->SBC and from Internal 5v En. Place a jumper on SBC-5V*. << one jumper set

    vs

    Alternatively the protection can be bypassed and the SBC can provide 5V for the Duet using the "SBC -> 5V" jumper. In this case the 5V->SBC and the SBC->5V* jumpers are both fitted. << two jumpers set

    yes, i'm going to do further setup and learning.

    thanks



  • Another option is to connect to the microusb of the duet to supply power.

    (I've deliberately disabled power to the usb port as I want the pi running even if the duet is powered down, but still want to have the serial console available for troubleshooting. So to avoid the pi powering the duet usb power had to be disabled)



  • @bearer thanks - removing both jumpers and powering duet from raspberry via micro sub did the trick.

    thanks again

    remaining question: why does the jumperable option to power duet from sbc exist?



  • they exist to be able to control the who powers who and to avoid having two supplies working in parallell which doesn't always end well. and its more flexible when you have options.

    be mindfull of how much 5v and 3.3v power you draw, and the wire gauge of the usb cable, you could risk brown outs if the wires are thin


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