That same feeling, when the electricity in the socket suddenly ended...

[ivan-lipunov 15]

In the area where I live quite often there are cases of sudden cut-off. For a variety of reasons. And Yes, the printer is connected to a source of emergency power. But the problem is that his stock lasts an hour and a half of work. At the time, as printing can last several times longer.

In this connection there is the following idea.

Create a file on the sd-card, approximately the following format: printer status (0 - print was not started/she has successfully completed, or 1 - printing was in process), the name of the file with g-code, the last known command to the printer from the code. In the process of starting the print file is updated (0 changes to 1, is the file name), in the printing process the commands sent to the printer is written to the file. If there is a power outage, after restarting the printer menu, select print from the last khown condition. After printing the file is reset to default state.

Accordingly, there is minimal error in the finished model and the saved nerves/material/time/money.

It is feasible to implement, or there are objective limitations because of the nature of the Arduino platform?

[nallath 1,123]

Writing to an SD card is dangerous, especially when there is a chance of random power surges. If you're writing to an SD card and the power drops, there is a chance that you ruin the entire card.

[tinkergnome 927]

It is feasible to implement, or there are objective limitations because of the nature of the Arduino platform?

 

Actually - there are such limitations too. The Marlin firmware on Arduino can open only one file at a time for a reason. Each file access needs a separate buffer and memory is pretty scarce already (is this the right word...?).

And keep in mind that you would have to backup (and restore) all axis positions, the current print settings and the file position too.

In addtion: if you're using the heated buildplate the print is ruined anyway, if it cools down on a power fail.

At least some thoughts about a resurrection system are existing, here is an example. But this also implies that the printed object does not loses the adhesion to the buildplate.

My conclusion:

Probably saving the printer status is feasible this way, but the whole effort is useless if you're not able to keep the buildplate hot...

[ivan-lipunov 15]

Thus, under the current design of the motherboard has limitations, such as the buffer size/lack of multithreading and the absence of an external source of power (battery pack). Theoretically, in the absence of electricity,by the signal of external source (via USB) printer can pause printing, leaving only the heated bed. But can't even imagine the amount of change in the firmware required for this.