Communicating via USB while printing from SD?

[derbroti 4]

Hi,

the topic basically says all: Is it possible (honestly not tried yet...) or better asked can it lead to problems (too much traffic for the little atmega to handle?) when I try to send gcode commands via USB during a print from the SD card? (Of course no movement commands just status requests)

Cheers,

derbroti

[derbroti 4]

Ok, I read through the marlin firmware and the result (if I got it right) is okay.

The main loop first reads from serial in a loop until the buffer (8 commands) is full or no more serial communication happens and then from SD again in a loop until card EOF or buffer full.

So, if I send too many commands fast enough, I could fill the buffer with serial commands (as they will be read first) and starve the SD communication and make my print fail...

...this should be unlikely because generally, when just occasionally sneak in a command it should work fine as the serial loop would stop and it can happily fill up the buffer with SD commands.

Edited April 8, 2016 by Guest