Fighting with computers

While some friends were waiting for their first Printrbot off Kickstarter I had already built one with the parts Brook Drumm posted on Thingiverse. That was quite a while ago. It was a cute little machine that I sold to a fellow reprapper. Last year , while I was working on a closed-loop DC motor controller for replacing the steppers of our 3D printers, Brook Drumm offered to help and sent me a free Printrbot Simple Metal, fully assembled to be used as a testbed printer for such type of motion control. I had a difficult time trying to convince the taxman that the printer was really a gift and eventually I had to gave in and pay some custom taxes although that was not really a product I was buying and the sender was charging me no money for that. I was surprised of how compact the thing appeared and how smooth and solid all the axis moved. However, the 3d printer was not intended to be used as a 3d printer and the first thing I had to do was to partially disassemble a brand new unit

My 4xiDraw project has been a source of inspiration for other projects. A while ago I mentioned how to add wireless connectivity to a serial-based device, but for a subject I teach I wanted to get a bit deeper on the details about stepper motor timing generation for trapezoidal (or any other) speed profile. While this functionality is implemented in every CNC or 3D printer controller software, most of them are based on GRBL development, which is efficient but not easy to grasp on a first look. There are many different but related algorithms working together there. Just by chance I bought a Wemos D1 board that replaces the Arduino UNO Atmega 328 by an ESP8266 but keeps the UNO form factor. It was a weird proposal but I bought anyway as we all know that anything that stamps wifi on it makes it a better product. I have used the ESP8266 in the past, through the Arduino IDE, but I have never needed to achieve any realtime operation. But once I checked that CNCshield board could be