MK3 + Raspberry Pi model _A_ +
Hi All,
has anyone experience connecting a RPi model A+ on the extension connector, instead of the RPi Zero ?
ref: https://www.raspberrypi.org/products/raspberry-pi-3-model-a-plus/
visually it looks like a good fit, but I wonder if the Einsy board is compatible size and power-wize.
The quad-core model A is can to draw up-to 5W of power on full CPU load (1A@5V) where the Zero would be less than a third of that. I want to make sure I don't toast the Einsy's power regulators.
Is there maybe a spec availble on how much power can be drawn from the 5V rail? Looking at the schematic, it looks like the 5V is regulated by a LM25011MY which has a maximum rating of 2A, not sure what the remaining budget is.
ref: https://www.pidramble.com/wiki/benchmarks/power-consumption
Thanks for the feedback
Re: MK3 + Raspberry Pi model _A_ +
The RPI 3 A+ is quite a bit bigger than the RPI zero W so it would be tough to fit it into the Einsy base.
It could be connected by a making a cable to connect between the Einsy Rambo board and the RPI 3 A+.
It would be easier just to connect it up via the USB port.
This article from The MagPi has a comparison of 3A+, 3B+ and ZERO W boards.
https://www.raspberrypi.org/magpi/raspberry-pi-specs-benchmarks/
Re: MK3 + Raspberry Pi model _A_ +
The A+ Einsy mod is being worked on in "602 Wasteland" discord group. Fitting an A+ in the Einsy case is possible as it seems. It has to be farther away from Eins y because of all the connectors, the full-size USB port in particular, and clearance to the X-motor path becomes an issue, but initial fits induce optimism.
These renderings show it with Bear mounts, but it's trivially adaptable to the sock frame.
The questions not yet answered are: does the 5V rail provide enough current to power the A+, potentially with a USB webcam connected? Will it interfere with cooling of the TMC2130 drivers on the Einsy board?
Because the 24V rail is available on the same header, power problems are potentially solvable by using a step-down converter. Cooling problems can be solved by adding a small fan.
Oh, and the 2x20 header will have to be unsoldered from A+ and replaced with 18mm one. So this mod will not be for everyone.
If this can be made to work at all, it will be eventually published on TV.
Re: MK3 + Raspberry Pi model _A_ +
Could you power it using a external source?
Re: MK3 + Raspberry Pi model _A_ +
An external supply is always an option ...just need to keep an eye on ground loops (and don't connect any supplies); but I don't expect problems there ... it's just a little less convenient, but given the limited regulator capacity on the Einsy board it's probably a wise choice anyhow ...
Re: MK3 + Raspberry Pi model _A_ +
Just got a Pi 3 A+ and made an attempt at mounting it, ran into a few problems:
My A+ had a header attached, so I made a little board with extensions for the pins that need to penetrate the einsy board for the interface connector, this meant with the original pi w case door, the board stuck out maybe 5mm or so - which meant that the X axis stepper coming down would hit the board.
Then I tried just using jumpers and leaving the board outside and away.... but unless you use the 0.16 nightlies of octopi, it won't boot on the new Pi 3 A+. That means the PrusaPrint image, based off the last stable release, also won't boot.
Power is likely fine from the Einsy board, it's switcher is rated to 2A in the data sheet (though this is external component dependent), and I can't imagine the onboard electronics use up more than a couple hundred mA from the 5V rail. The Pi 3 A+ uses less than 500mA in continuous high processing situations, so there's a lot of headroom, but if you hook up a camera and it consumes a lot of power it could be an issue - I think a typical webcam is in the 200-300mA ballpark, though, so I plan on trying it with a Logitech C615 when I get it up and running.
For now, though, I'm going to wait a bit. Also have an enclosure to build, and the Pi Zero W I've got in there works well enough without the camera. Hopefully in the week or two it takes to get the rest of my stuff done, we'll be closer to a new stable release for octopi that brings Pi 3 A+ support, and I can assemble everything up.
Related but not directly useful: the Pi 3 A+ draws 150mA when powered up but not booting, when I get an appropriate boot image I'll measure it with the C615 connected too - easy enough to do with a bench power supply.
RE: MK3 + Raspberry Pi model _A_ +
Idk but my new rasberry pi a+ won't boot sd card (tried same card with zero and 3b+ and it works fine,) anybody may know the reason?
RE: MK3 + Raspberry Pi model _A_ +
@dajmasta
did you find way to fix it? bc just installed A+ but it wont read prusa print firmware.