A 40 digit calculator using a Ras Pi, Java, 7-segment readouts, MAX7219 chips driven slightly out of spec (ab)using the SPI pins. Two 4x4 keypads to form an 8x

A 40 digit calculator using a Ras Pi, Java, 7-segment readouts, MAX7219 chips driven slightly out of spec (ab)using the SPI pins. Two 4x4 keypads to form an 8x4 keypad so it will be a scientific calculator. Found a Java library to do transcendental functions using BigDecimal. All of this on a breadboard. (I'm a software guy who doesn't know which end of a soldering iron to pick up.) Other project. A 64x64 RGB LED display driven by a Teensy 3.2, in C++. A friend who does hardware but not so much software sent a beautifully assembled rig in a very nice enclosure. No blog.