When Robson Couto’s LCR meter died after many years of use and abuse, he knew he needed a replacement. After scouring eBay, he finally settled on GM328A meter. For around $10, it’s an impressive device with a 60x128 full color display, and ports for frequency measurement, square wave and PWM output, voltage measurement, and of course, an interface to test discreet components like resistors, transistors, and capacitors.
What makes this unit especially cool is that it’s based on the ATmega328 processor (of Arduino Uno/Nano fame), and Couto realized that it would make an excellent development board. What ensued next was him reverse engineering the board, as firmware is already available here. Along the way, he found that the frequency measurement circuit wasn’t properly connected, which he fixed with a blob of solder. Once that was taken care of, the frequency function worked as it should, and apparently preempted any future issues.
When it came time to modify the firmware, Couto simply pulled the ATmega328 chip out of its socket, then replaced it with a new model. After adding a temporary programming port to the device, he took on the “small” task of programming it to play Tetris, using the built-in encoder that also includes a pushbutton as an interface. The game looks great as demonstrated above, and even features music to go with the square figures falling from the sky! Code for this hack can be found here.