Is this one of the best years for 3D printing? Well, I’m acquainted with some awesome news and I certainly see more people getting in touch with this technology. The 3DP industry is expanding its horizons and as Moore’s law established, with the passing of the years, it must be smaller and cheaper. MP Select Mini is a good example of the words above; A good – small and cheap 3D printer for less than $200. Does it worth it? Well, like all 3D printers, it has its own issues and missing features, but you guys know, even the expensive ones have.
First of all, We will focus where the MP Select Mini shines: its electronics.
The controller board is totally a game – changing and worthy to write. In all reviews and YouTube Videos I found , the acceleration ramp is the best thing on this machine, while traveling from one end to another is close to magic. Smooth and precise.
The electronics board for this printer is a 32-bit ARM Cortex M3. I just can say WOW! that’s simply amazing considering most standard 3D printer’s controller have an 8-bit ATmegas.
How MP Select Mini works was beyond my understanding, until I read Robin Reiter’s project.
Robin Reiter Hacked the Monoprice 3D printer using reversed engineering. Specifically, the main controller and the display controller. With his oscilloscope attached to the serial line in both controllers, he discovered the baud rate (500 Khz) that was the trick; the commands appeared in human-parsable text. He also faced with a small web server built into the Mp Mini printer. After a small inspection, he finally found all the things that you want in a 3D printer, then sent G-codes directly from the controller board, got a list of files on the SD card, etc.
Robin posted on Hack A day How he did reverse engineering for the MP Select Mini . In his own words:
My goal is to write a new firmware for the UI controller of the MP Select Mini 3D Printer.
I’m thinking about Interesting features like a bed leveling assistant, a guided filament change or even funny things like a total runtime counter.
But before we can start developing any software we obviously need to reverse engineer all the related electronics. I’ll go through the communication between both the motion and UI board and also find out what display driver they used by sniffing the SPI traffic.
Before Robin started coding the new firmware, he first needed to work on two things. These are the two things:
1.- MP Select Mini Communication in the board
Get to know what and how is happening between the UI and the motion controller board. This time Robin uses a scope to see the bauds in both communication boards.
2.- Mp Select Mini Display is attached to the board
The MP Select Mini has a 320×480 TFT display attached to the board. These are actually glued together with double-sided tape.
Robin success on hacking the electronics and after that, he starts writing his own firmware.
On the display board, Robin found other special features like an SPI display driven by an ESP, and a big flash chip sitting off to the side. This is where he finds the model of the display and makes a simple diagram to draw the text on the LCD.
Robin is still working in the project, so here’s a full explanation video about the whole process: