Low-cost mini movable laser galvanometer projection based on Hangshun MCU

This project implements basic laser projection functions, including PCB, driver, and 3D printing shell, with a volume of 5x4x5cm. The Hangshun HK32F030MF4P6 main control is used to drive two motors to control the XY-axis reflectors respectively, using the persistence of vision effect to achieve projection.

Designed for low cost, the unit price of the BOM without battery function is only 5.81 yuan, the price of the complete set including the shell is less than 10 yuan, and the total price with lithium battery is less than 25 yuan (large enough lithium batteries are really expensive). MCU-IO multiplexing is compatible with stm8s103 and leads to the SWIM interface. Changing the main control IO will not cause the function to be incompatible, except that stm8 does not have I2S function and can only be simulated by software.

Sorry, it’s a semi-finished product, it will be improved later (@2021-03-31)

function points

• Low cost (less than 10 yuan for the whole set without batteries)
• Laser galvanometer projection
• Switch projection scanning mode, geometry/analog CRT/analog lattice
• Infrared remote control
• Button control
• Status Indicator
• Buzzer sound
• Optional lithium battery powered, removable, can be used without a power cord

Note: The above optional functions are due to cost considerations. Not soldering optional functional devices will not affect the basic functions.

Appearance Gallery

Principle introduction

As we all know, mirrors reflect light. When the light point passes through the curtain, a glowing trajectory will be seen due to the persistence of vision effect. Install a mirror on the motor shaft, and the light path changes as the motor rotates. In addition, the motor moves back and forth within a small angle, and the reflected light from the mirror will form a strip.

Install the two motors at 90 degrees, and their reflected light will cover the flat area. One motor controls the X-axis and the other controls the Y-axis to achieve two-dimensional control of the light spot position. When the laser diode switch is turned on and off, it can be freely displayed and projected.

In order to save costs, we used cheap audio DAC and audio amplifier to control the motor. The main control uses the I2S interface to output audio signals and drives the motor to deflect to achieve projection.

Parts and Materials

• 5V1A power supply
• 3V dot laser diode 6mm
• Mini coreless motor*2
• Reflector*2

3D design (temporary scaffolding)

Model

3D printing

Physical display

FQA

Q: Why is the non-standard design of both copper laying and wiring used in the PCB?

A: Avoid BUGs and ensure that the DRC and preview images look normal, although no BUGs are actually encountered.

Q: Why does the buzzer not have onboard pin header connection?

A: For the convenience of assembly, no in-line buzzer is used, leaving enough space for two motors.