Hello,
I create this topic (I do not know if it is in the good place) because I developed a solution that speeds up the copy on the printer's SD card from octoprint (transfer speed between 10 and 30mo / s).
this project was realized with the help of Janpolanton (https://www.lesimprimantes3d.fr) who designed the PCB from my prototype 1.
This project is called SD Switch Fast Copy (SSFC), it is a plug-in card on a raspberry PI 3 3B + and 4 (in test), this card is accompanied by an octoprint plugin that I developed.
Documentation link: https://hotends.dozuki.com/c/EN
pre order link: https://www.hotends.fr/fr/home/76-sd-switch-fast-copy.html
video presentation FR: https://www.youtube.com/watch?v=pPnYAxwhoJE&t=74s
comparative video: https://www.youtube.com/watch?v=FNM3-IcqQLM&t=3s
and video attached showing the PCB and the plugin in action (zip)with ssfc module.zip (1.8 MB).
In a nutshell, the plugin replaces the copy system on the SD card (octoprint).
I created this solution because I encountered various quality problems with USB printing (blob, micro pause ...), but I wanted to keep the comfort of octoprint, so I created this solution.
I tested different alternatives, such as the wifi SD card, but it was relatively slow and very unstable...
best regards
1 Like
Is this sort of an A/B switch for the SD card, in essence? (Does it start with the printer using the SD card, then switch to having the Pi use the card during the copy and then revert back to the printer using the SD card again?)
yes that's it, by default, the SD card is on printer (for security), and when a gcode is sent to octoprint in the SD card section, the pi take control of the SD and initiate the copy.
Interesting approach (and it appears to be much faster).
I think I would have done this as an inline gadget that is cabled between the printer and the Pi and powered by the printer. In this way, one side includes a Type-A USB plug for the Pi and the other end presents an SD male connector for the printer. It might also then have a two-pin connector for 5V from the printer. Finally, it would have an SD card connector to accept the printer's SD card.
I am not sure of the function you are describing.
An SD card can only be connected to one computer at a time, so I made a kind of switch, which is activated only in case of a copy, but it must be piloted
the module that I propose here uses the GPIO for the power supply and the activation of the module, then 2 extension sd are available to add an extension sd to micro sd + adapter micro sd to usb (raspPI side) and the other for connected an extension sd to micro sd (or sd to sd) for connected to the printer.
the choice to not only use the GPIO connection was made for several reasons.
- Enabling SD support on GPIO disables WIFI.
- that used a lot of GPIO PIN
A photo is always more talking than my approximate English 
