Open Source | Rubik’s Cube Solving Robot Based on Raspberry Pi RP2040 – Solve in 7 Seconds

This project does not require a camera; it uses two color sensors to scan the colors of all edge and corner pieces, and employs a reduction method to find a solution within 22 steps, and then restores the cube according to the solved result.

Let’s take a slow-motion look:

Note: Rotate the cube in a specific pattern so that all sides pass through the color sensors at least once. In addition to the edge and corner pieces, the color information of the center pieces is also needed; the current project structure cannot scan the center pieces, so the orientation of the center pieces needs to be fixed when assembling the cube..

Hardware Design – Connect the GPIO of the RP2040 microcontroller to the stepper motor driver, color sensors, and Hall sensors. Other than SPI and UART, all other pins only use GPIO without any other multiplexed functions.

Note: The Hall sensors can only be powered by 5V, while the RP2040 microcontroller IO operates at 3.3V, requiring level conversion design. FLASH is optional; if not used, the average number of solving steps is about 32.

Structural Design – It is recommended to 3D print using ABS material with a 0.4mm nozzle, 0.2mm layer height, 5 top layers, 5 bottom layers, 4 shells, and 20%-40% infill, generating supports.

Firmware Compilation – It is recommended to use a Linux system for development, following the scripts in the official RP2040 documentation to set up the development environment. For relevant source code and files, refer to the latest open-source material link.

Not counting processing costs, the material cost is about 200 yuan for one unit.

Main materials on the motherboard:

The PCB can be obtained for free in small quantities; in larger quantities, it is estimated to cost about one or two yuan; three heatsinks are about 1.5 yuan, the crystal oscillator is about 0.3 yuan, Type-C socket is 0.38 yuan, RP2040 microcontroller is 3.91 yuan, three HR4988 chips are 6.24 yuan, W25Q16 is 0.9 yuan, AMS1117 is 0.3 yuan, CH224K is 1.1 yuan, W25N01 is 5.5 yuan. Other materials are quite cheap, but cannot be bought in small quantities, so there will be a lot of leftovers.The total cost should be within 30 yuan.

Complete machine materials:

Three stepper motors cost about 72 yuan, a magnetic Rubik’s Cube costs around 20 yuan, two square pot magnets cost 9.4 yuan, a 4010 fan costs 7 yuan, three Hall sensors cost about one or two yuan, two color sensor modules cost 27 yuan, a flange coupling costs 2.8 yuan, aluminum strips cost a few yuan (if you can process them yourself, it’s very cheap; if you have to customize them, it might be very expensive, so printing a few more in 3D is a better deal). ABS material costs around 10 yuan for about 280g, and if you don’t have a 3D printer to customize, it’s about 0.2 yuan/g. Other small parts are hard to calculate, but not expensive.The total cost should be within 170 yuan.

Accessories: You can use any power supply between 12-20V, preferably above 2A, which most electronics enthusiasts have. If you have a PD-compatible Type-C charger, you can use it directly. Just be careful with the wiring when connecting the positive and negative terminals.

The small microcontroller interprets countless possibilities

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