Bachelor thesis project by Vaclav Zeleny under a supervision of David Novotny – the goal was to design and manufacture a magnetic field display usable as a fun tool for discovering magnetism but also for serious applications (e.g. easy work with permanent magnets).
A matrix of Hall sensors (8 x 8 in a single module) provides information about the vertical component of a magnetic field induction, the analog output value is multiplexed to ADCs and scaled to colored shine of programmable daisy-chained RGB LEDs (at 60 frames per second). STM32 microcontroller takes care of all the signal acquisition, data processing and presentation. Modules can be coupled together, there is a serial interface which allows for dynamic control of presented range of magnetic field between the modules (max. ±75 mT, noise is 26 μTRMS in a band of 0-30 Hz). Four modules with a total of 256 sensors and RGB LEDs are presented in the video. The device can also send the measured data to PC for further processing. (the video is in czech language)
Are you interested to build one? You can find all the data at the university repository: https://dspace.cvut.cz/handle/10467/94462
Please contact us in case you want to run production for commercial purposes.