Which Firmware?

Choosing the Appropriate Firmware

Find firmware and supporting files in the assets section of the latest release.

The file name of the firmware identifies the compile-time options (described below) chosen for the particular firmware (.bin) file. Select the variant of firmware that matches your printer's stepper motor wiring, the power adapter in use, and the desired fan control.

e.g. [mpmd_marlin_1.1.x][-119r06][-SM0001][-ACfan][-05Alimit].bin

note: brackets [] are not part of the file name

Stepper Motor Directions

Sadly, Monoprice does not seem to configure the stepper motors in its MP Mini Delta printer in a consistent manner. So far, we've identified two configurations -- the XYZ motors move in one direction with the E(xtruder) motor moving in the opposite direction. One can imagine two more configurations (where all motors move in the same direction) may be "in the field" as well. To accomodate these configurations, we build four variants:

• -SM0001 - XYZ positive, E negative (seems to be the 2018 wiring)
• -SM1110 - XYZ negative, E positive (seems to be the 2019 wiring)
• -SM0000 - XYZ positive, E positive (we've not seen this, yet)
• -SM1111 - XYZ negative, E negative(we've not seen this, yet)

Thanks to @Jaxtheripper for reporting that -SM1111 has been "spotted in the wild".

TIP: While you are still on stock firmware, send M503. 2018 wiring corresponds to Invert axis: M562 XYZE XYZABCD---+-+-. Make sure your printer still homes correctly to make extra sure that this is correct for your printer.

TIP: If you are uncertain about which (stepper motor) variant to chose, try this procedure:

1. make your best guess, and install the firmware (-SM0001 or -SM1110 is a good choice);
2. center the print head, then home the printer, BUT remove power when the stepper motors begin to move;
3. note the motion of the stepper motors -- all three should be moving up toward the top of the printer;
4. if the stepper direction is not as expected, select another variant of the firmware
5. (without filament loaded) use the display to move the E stepper to check its direction -- CCW for the down arrow, CW for the up arrow;
6. if the stepper direction is not as expected, select another variant of the firmware.

Automatic Fan or Part Cooling Fan

The Monoprice MP Mini Delta has one fan that serves as both the hot end cooling fan and as the part cooling fan. Since Marlin is designed to drive two separate fans, we provide two variants to designate the role of the printer's single fan:

• -ACfan - the fan operates automatically as the hot end cooling fan
• -PCfan - the fan is controlled (M106/M107) as the part cooling fan

TIP: I think for most users, the -ACfan option is the proper choice. When the fan speed is set to zero, it will operate whenever the hot end is above 50°C to minimize "heat creep" issues. Otherwise the fan speed is controlled via M106/M107. The downside is that unless the fan speed is deliberately set to a low value other than zero (at the start of a print), the fan operates during the initial layers of printing which may not be desirable. In our experience printing PLA with the firmware, this has not been a problem.

60W or 120W Power Supply

Monoprice provides a 60W (5A@12v) power adapter to supply power to the printer. Though the power supply is adequate, it cannot supply power to heat the hot end and the heated bed at the same time. With a larger 120W (10A@12v) power supply, this restriction does not exist. To accommodate both scenarios, we've two variants of firmware:

• -05Alimit - for use with a 60W (5A@12v) power adapter
• -10Alimit - for use with a 120W (10A@12v) power adapter

TIP: Using the stock (60W) power adapter with Marlin firmware works just fine, but please see this discussion about Marlin's "thermal runaway" error condition.