Monoprice Select Mini (V1, V2, V3) Firmware (MPSM)

My Monoprice Select Mini V2 was my very first printer in 2017. To this day, I still print on that little thing. Of course, I've had to mod the heck out of it, but that's what I loved doing from the start.

Anyways, to cut to the chase, I've realized there probably are many out there who've come across these machines inoperable and that may be due to a firmware issue. Back in the day, a website called "mpselectmini . com" presumably run by the user MatthewUpp (https://www.thingiverse.com/groups/monoprice-select-mini-owners/forums/general/topic:19510). Many of the files, info, and instruction can still be found here https://drive.google.com/drive/folders/0BxyFI3iDaicLODVZOHI4SzZBNlE?resourcekey=0-bUBCpfJxeD-YreH5Q2M0Qw. But like all good things in this world, the website domain is no longer supported and is no more. However, due to the MPSM platform's obsolescence, I figured the website wouldn't be up for much longer, so I archived a lot of that data, including MPSM firmware. I haven't tested any of this firmware so obviously use at your own risk. I figured someone out there might want to at least give re-flashing their controllers a shot before either trashing it, or swapping out the controller for a modern on (the best option imo).

I want to thank MatthewUpp for all his work to help all of us troubleshoot, diagnose, fix, and most importantly learn about this printer. I would undoubtedly never attempted 3d printing if it wasn't for this cheap and community supported printer. So thanks again to MatthewUpp and the MPSM community!

Here is some additional data and information I was able to archive for this printer:

--Default E Steps

X Stepper Motor

V1=93.00, V2=46.50, V2 (Mid June 2017)=93.00, V3 (Pro)=93.00

Y Stepper Motor

V1=93.00, V2=46.50, V2 (Mid June 2017)=93.00, V3 (Pro)=93.00

Z Stepper Motor

V1=1097.50, V2=548.75, V2 (Mid June 2017)=1097.50, V3 (Pro)=1097.50

Extruder Stepper Motor

V1=97.00, V2=48.50, V2 (Mid June 2017)=97.00, V3 (Pro)=97.00

MISC:

1) I've only ever been able to establish serial communication from a physical connection from my computer to the printer only with Cura, although manual g-code injection is severely limited (save to EPPROM via sd card only).

2) If your printer stops or never starts a print, it's most likely because of Monoprice's firmware. They added thermal runaway safety in V40.156.2 (I think that's the right version?) which will stop the print and turn off all heaters and "freeze" the printer if any thermistors aren't close enough to the target temperature in a given threshold. So, for me, the bed always struggles to reach temperature at the start of a print and my printer will freeze right after it starts. I found that a decent fix is to add custom starting g-code that heats to a target temperature, waits, then drops the temperature by around 3 degrees. Or just don't set the heated build plate to above 50C.

3) The Monoprice firmware will not allow you to turn the fan off if the hotend is above 70C ish. However, you can turn the hotend fan off at the end of a print if you insert a dwell "G4" (wait) gcode command for around 300 seconds. You should time how long it takes your hotend to cooldown below 70C and code that into the G4 command (with some added time for a buffer). The printer will say the job has been completed and keep the fan on, however, after the set time and if the hotend is below 70C, the fan will shut off. Note that you won't be able to start a new print until this time period passes. You can just shut off and on your printer if you want to immediately print.