Send GCODE from SD card attached to ESP

[probonopd]

I would like to attach a SD card to the ESP8266, be able to upload GCODE code to it over WLAN, and have the ESP8266 send that GCODE over the serial connection to the 3D printer. I think that this should be pretty straightforward to implement, but the sending part must listen to "ok" and other such messages coming from the printer, and only send further code if they arrive.

[luc-github]

straightforward to implement, well not so sure, ESP as host a working solution not really IMHO

ESP8266 is not a multitask MCU - some part can be emulate but not sure it will be Ok, when it could be Ok for CNC, it won't be good for laser and FFF printer.

GCODE need to be send to printer in regular flow to avoid any delay, why ? because if the flow is too slow - laser will stay too long in same place and burn too much, or in case of 3D printer melted filament due to inertia and gravity will continue to go out of extruder and it will result an over extrusion.
Flow will be slow down because ESP send query about position, temperature, handle answer to web page etc... to sum up, unlike octoprint working on multitask OS, ESP is monotask, the printing result will be terrible

[luc-github]

I think ESP32 would be a better candidate for acting as host but SDK is still in early stage

[probonopd]

Have you actually tried it? I think the 3D printer has some internal buffer for GCODE, so it is not as time-critical as you may think. The 3D printer asks for more GCODE well before it actually prints it.

[luc-github]

No I did not because of what I explained above and based on my experience of ESP usage

Now you are free to try 👍

[probonopd]

I guess that's what I must do :-)
Do you know how to send GCODE?

[luc-github]

have many way - simple gcode without answer check, with answer check, with line numbering + GCODE + check sum, text mode, have also binary mode like repetier, etc...

[probonopd]

Do you know a good place where to learn this?

[luc-github]

I would suggest you to start by a firmware flavour - seems you use marlin - start by marlin then when you know well the GCODE and the printer communication process of this FW, have a check of marlinkimbra to see if they work identicaly (they don't 😉 ) , then study another one like repetier or smoothiware or reprap or ultimaker to see the difference and the common part, this how I did for ESP3D, originally was only for repetier then adapted for smoothy then marlin then marlinkimbra, I did not worked on reprap because duet3d has an embeded ESP so was not necessary

I suggest you also to study how repetier host works or pronterface or cura, for each one, all or part of their source code is available so can be a good reference of communication process

[probonopd]

Got it. So essentially port https://github.com/Ultimaker/Cura/blob/master/plugins/USBPrinting/USBPrinterOutputDevice.py to C, correct?

Or this, which is C++:
https://github.com/NeoTheFox/RepRaptor/blob/master/sender.cpp

Have you done it somewhere else as part of ESP3D? or know any Arduino sketch that does it?

[luc-github]

well ESP send gcode but simple ones, you must also handle the fact that the esp tx buffer is limited to 128 byte so you must not overload it - you may check what it is done for SD upload/transfert in code which is like acting as host but without printing

[probonopd]

I have successfully printed an object from SD card attached to the ESP8266.
Edit: Uploading to SD card is also working now (at least with exactly one SD card).

[luc-github]

I do not use the hacks you use, so coud be a side effect of being "too" fast - try add delay(0); at the end of upload function before line 106 or try remove them to see if they are the root cause

[luc-github]

And I do not use esp native SD library but sdfat one because I want lo support long file names

. and I regularly upload 10Mb files without issue and it is pretty fast , same speed as my wifi SD card I think

[probonopd]

Right now I am trying to get to a minimum viable implementation that has no dependencies outside of what Arduino 1.6.11 with esp 2.3.0 provide. I will use this to fiddle with uploading directly from Cura. Once I have that working, maybe you may consider to integrate it properly into ESP3D.

Can you point me to the code where you upload a file to SD card (not the printer's SD card but an SD card attached to the ESP)? Searching for SdFat.h in this project found nothing.

[luc-github]

The project I mentioned is not public yet as it is linked to special hardware which is not owned by me, but will be released soon, then I will release the code, sorry

Anyway SD upload code is same as upload to spiffs, also command ESP700 is doing same as you do for macro purpose, because no need robust sending, but for long print it is mandatory to check what printer ack for each command sent IMHO