Quote
greenonline
Just to re-iterate, the answer above is for power on of the printer. However, I am looking for a solution for a printer already switched on and it is the insertion of the SD card which triggers the printing.
It does not seem like an auto print, when inserting a SD-card, is to be found in the current program code of Marlin.
You might consider making a feature request here: [github.com]
I do not think that it would require much work to implement a "card.autoprintfile()" function in Marlin.
It seems to me that a call to such a function could happen at line 5172 right after:
"
else
LCD_MESSAGEPGM(MSG_SD_INSERTED);
"
in the file ultralcd.ccp