Power Pi from Duet 3 Mini 5+ shorting 5V_Ext to 5V_SBC

keyz182

I currently have both the Pi and 5V_EXT_INPUT powered from external 5v. In an efforts to clean up wiring, (and potentially reduce noise to combat BAD CRC32) I'm wondering if it's possible to short 5V_EXT_INPUT, 5V_SBC, and 5V_SELECT on the 5V selection jumpers so that the pi gets powered from the 5V_EXT supply over the ribbon cable?

Looking at the schematics, the 5V_EXT_INPUT and 5VSBC rails only have inputs and jumpers attached to them, so it seems like it'd be OK, but want to make sure.

keyz182

Well, I tried it, and nothings gone pop yet

Nurgelrot

@keyz182 Can you post a pic of what you have done? with suitable disclaimers as im sure it not a supported config. I'm powering the board and pi from an external 5v supply as well. I like the way I have it all working so I dont think I'll change it but nice to see options....

keyz182

@nurgelrot Just reassembled the panels so can't take pics.

All I did though was jumper the internal 5V disable pins, and jumper all 3 pins on the 5V_SELECT pins together.

Then I have a 5v supply connected to the EXT 5V pins.

dc42

@keyz182 said in Power Pi from Duet 3 Mini 5+ shorting 5V_Ext to 5V_SBC:

I'm wondering if it's possible to short 5V_EXT_INPUT, 5V_SBC, and 5V_SELECT on the 5V selection jumpers so that the pi gets powered from the 5V_EXT supply over the ribbon cable?

Unless you are powering high-current 5V devices from the Duet, I suggest doing it the other way round. Ribbon cable is not designed to carry high currents, and a RPi 4 needs quite a lot of 5V power.

keyz182

@dc42 So power the pi from 5V directly, drop the ext_5v connection, and just use SBC 5V?

Seems the more sensible approach now that I actually think about it. I'm only running a set of 7 neopixels off the 5v, so could probably just use internal 5v. I guess I was thinking future proofing, but I think I'll just address that in the future

Nurgelrot

@keyz182 I was wondering about the Internal 5V Disable jumper. Not talked about in the wiring diagram 5v options. I'm assumed I should have it closed if I'm powering 5V externally

keyz182

@nurgelrot Check the table here - https://duet3d.dozuki.com/Wiki/Duet_3_Mini_5plus_Wiring#Section_Description_of_Connectors_and_indication_LEDs

Specifically 1x2 Jumper: Int_5V_Disable and Note 2 at the bottom. The diagram on the top of the page shows where it is.

Nurgelrot

@keyz182 Man both myself and my browser's search function are blind.... okay well i set it the way i should have it through dumb luck. I can live with that.

Electriceye

@keyz182
Yes, this topic IS old...er but alas- I need to clarify something as I'm nearing the 'power on smoke test' ; ) for my RatRig VCore 3 with Duet 3 Mini 5+ and really do not wish to see the 'magic smoke'

In the thread above, there is a reference link to:
Check the table here - LINK REMOVED as I need at least 2 reputation to post links...sigh

When I try that link- it is el broko, non-functional, kaput!

So... I looked around and according to this resource-
duet3d dot kom/en/How_to_guides/Wiring_your_Duet_3

The Duet has an on-board 5V regulator which is powered by the VIN input (12-24V).
Unless you plan to provide an external 5V source, you should at this time check that there is no jumper on Int 5V Disable or 5V Select.
Optionally, external 5V power can be supplied to:

'5V IN' pin on EXT_5V connector. In this case, add a jumper to the 5V Select jumper between '5V_EXT_IN' and '5V_COM' pins, and add a jumper to Int 5V Disable.
In some cases you may want to power the Duet from the 5V output of an SBC connected to the SBC header. Note that the total power of the Duet and peripherals must be factored into the SBC power budget, and should not exceed 1A. Powering the SBC from the duet is not supported. In this case, add a jumper to the 5V Select jumper between '5V_SBC' and '5V_COM' pins, and add a jumper to Int 5V Disable.

Right...so here's the issue-

My Power supply: Meanwell LRS-350-24 seems adequate enough for this build (New, voltages all look good)
My Duet 3 MIni 5+ is running in SBC mode with an attached Pi3B+ with its own factory power supply (5.25v 2400 mA)
The Pi Factory power supply plugs directly into the Micro USB port on the Pi3B+
The Pi3B+ is connected directly to the Duet 3 Mini 5+ via the supplied 26 pin ribbon cable
The supplied 26 pin ribbon cable has 5 volts feeding the Duet 3 Mini 5+
My Panel Due 7 is connected to the Duet Board via IO_0 connector (I'm sure this draws some power)

The documentation here suggests:
duet3ddot kom/en/How_to_guides/Wiring_your_Duet_3
We recommend powering the SBC using its own PSU, to ensure stable voltage and sufficient supply of current to both Duet and SBC.

I know I can power the Panel Due 7 from the 4 wire connector I already wired up, but can also power it via the 10 pin serial cable, (albeit limited to 400mm length)

With these stated power requirements I've already listed, it seems there woukld be a 5v conflict waiting to happen if I don't choose my jumper setting correctly...which is what led me to this thread.

I'm sure I'll wait to add in some LED lighting,etc as well. Is my Duet 3 Mini 5 + going to be able to handle all this?

Sorry if this question is considered too obvious, I'm apparently missing my marbles today. Oh yeah- prob yesterday too.