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.