Do the Raspberry PI 3b and pico need separate power for usb connection?

[tianyi7250]

Connect the Raspberry PI and pico motherboards using usb.


I read in the pico manual that using a usb connection requires powering the Raspberry PI separately, is that right? (Red circle on the picture)


I see the voron0.2 pdf does not say that this connection also needs to be powered separately.
（And there's no raspberry PI power in the bom）

I also don't see how the Raspberry PI is powered on the voron0.2 pdf?


I have an idea,
Or use usb to connect the pico and Raspberry PI, and connect the uart cable to power the Raspberry PI, is that OK?

 

[claudermilk]

As the pictures show, the USB between the Pico and Pi is for communication. THe micro USB you have circled will go to a 5V power supply. The other option in the lower picture where the Pi is powered from the Pico AND it gets communication from there.
On my Trident, I have option 2 set up from my Octopus to my Pi4. Works just fine. On my V0 I have secret option #3: the Picobilicoal mod that comes with the LDO kit. USB communication between the Pico and PI, and power from the frame PCB.

 

[ineligible]

Connect the Raspberry PI and pico motherboards using usb.


I read in the pico manual that using a usb connection requires powering the Raspberry PI separately, is that right? (Red circle on the picture)


I see the voron0.2 pdf does not say that this connection also needs to be powered separately.
（And there's no raspberry PI power in the bom）

I also don't see how the Raspberry PI is powered on the voron0.2 pdf?


I have an idea,
Or use usb to connect the pico and Raspberry PI, and connect the uart cable to power the Raspberry PI, is that OK?


View attachment 3709

A note on illustration b here is that they've put the cable the wrong way around.

There's also the third option of powering the pi via the header (red and black cables (5V and GND)) and doing the communication via usb.

 

[ChrisA]

I read in the pico manual that using a usb connection requires powering the Raspberry PI separately, is that right? (Red circle on the picture)

Those USB A ports on the Raspberry Pi are designed to supply power to other devices. For example, I used that port to supply power to a very small Pico dev board. Power does not go the other way. And even then, the USB-A can supply only about 500 milliamps.

The most reliable way to power a Raspberry Pi or 4 is via the USB-C port. You can use the 0.1" head pins but be warned the spec on that connector is 1 amp per pin, max. The weak link on the header pin is the crimped-on female connector. They heat up after about 1 amp. In theory, a Pi can pull well over an amp of current. but in this use-case I doubt it would use much more. So using the header pin is marginally in-spec. Well it is until you start plugging in keyboards and mice, an. external disk drive and trying to charge your phone from the Pi. (but you don't do that on a printer.)

I am very new to Voron printers but not new at all to the technology they use.