RANT - I just destroyed my MK3S because of the RPi Zero port
A cautionary tale. I've being getting a frustrating "No LAN Access" message on a specific RPi Zero for several days, even as I swapped it between two printers and tried older versions of PrusaConnect. The RPi and PrusaConnects works fine when powered externally. After many frustrating hours, I tried to connect it with jumper wires, skipping the mechanical support on GPIO22. It worked. Somehow GPIO22 was preventing the pi from connecting to wifi. So I decided to snipped it off, and, excited that I finally solved it, I very carefully plugged it exactly where I was trying to avoid, the four pins next to where it should go. I knew I fucked up when I heard something pop as I turned the power on. Now, if I switch the printer on with the RPi in the right place, it doesn't power up. If I turn it on without the RPi, it screams and shows a temp anomaly error, while heating the bed and hotend for no reason. I guess I need an new Ensiy and a new RPi now.
Anyone knows what the other pins in the RPi port are used for? I don't understand why they're there if they're not needed, or why would the cause any sort of power shortage since they're supposed to be GPIO2 to 4 on the pi and gnd.
Needless to say I'm very sad right now.
RE: RANT - I just destroyed my MK3S because of the RPi Zero port
According to this
Einsy-Rambo Schematic PDF
and, assumed I read it correctly 😉 , those four pins go directly into the Atmega chip, they're all multi purpose pins and can all be used as digital ins/outs or analogue ins. The F ports 5 and 7 could be used for JTAG (but they don't have to be, it's just my uninformed guess), the H port pins 2 and 7 could be used as interrupts, communication or ADC. To learn more about how exactly they're used on the rambo one would need to look at how the Atmega is programmed for it. The code for the firmware is open source but it'd be a good amount of work to find out.
RE: RANT - I just destroyed my MK3S because of the RPi Zero port
Hearing a pop usually means something has left a visible sign of damage. Pull the Einsy out an examine it carefully. You may see what went pop.
RE:
I finally mustered the courage, and found the time, to attempt to find the fault. I'm now pretty sure I blew up something inside the Atmega. It still runs enough to run the firmware, control the LCD, read the the thermistors, and the push button of the click encoder. However, it can't control the heaters or read the encoder.
Also, looking at the schematic (thanks @outofcheese), it looks like I managed to run 12v through the Pi and into the Atmega. So that's cooked.
RE: RANT - I just destroyed my MK3S because of the RPi Zero port
Look at an upgrade path instead of replacing the Rambo board or search the forums for someone in your area that has upgraded and has one to get rid of.
RE: RANT - I just destroyed my MK3S because of the RPi Zero port
You could get a Mk3.5 upgrade. It replaces the Rambo board altogether and is a pretty significant speed boost over the Mk3.