The LogoCar is an attempt at simulating a real life Logo "turtle". "Logo is an educational programming language, designed in 1967 by Wally Feurzeig, Seymour Papert and Cynthia Solomon." - from wikipedia. Our LogoCar features a CPU & Controller that generate waveforms from a series of machine code commands. You could call it a "Turtle CPU".
It features the following;
- A Vivado project with implementation of CPU and Controller, which take an input program, and generate output waves for two stepper motors and a servo. It assumes a Basys-3 board is used, a TowerPro SG90 servo, and two 28BYJ-48 stepper motors.
- A Python project that can assemble turtle commands into CPU machine code; which can be used to program the LogoCar by pasting the RAM initalization line into Vivado, and programming the board. The Python project also features an L-System compiler, that turns L-Systems into turtle commands, which can be then turned into machine code for the CPU.
Uses servo to put pen up or down. The motors can move forward, backward, turn left, and turn right. Turning is specified in degrees, and moving in a line is specified in mm. Programmed by copying a RAM initialization statement into the Vivado project, and then synthesizing, running an implementation, and generating a .bin file for the flash memory.
It requires an external battery pack, and uses the JA and JB ports.
L-Systems in simple terms are just strings with interpretations. You start with an initial axiom (string), and have a set of production rules (string translation rules). You do one iteration, to generate a new string. After a number of iterations you get a very large string. These strings can be interpreted geometrically, to create complex patterns.
The geometric interpration usually only requires four simple commands; forward, backward, left and right. In this sense L-Systems and Turtle are perfectly suited for each other, which is why an L-System to Turtle Commands-compiler is included in this project. You can try and copy any L-System you find online, compile it, paste it in the Vivado project, and program the LogoCar's Basys-3 board; even with it's large degree of imprecision, the LogoCar will draw something resembling the intended pattern.
An L-system or Lindenmayer system is a parallel rewriting system and a type of formal grammar. An L-system consists of an alphabet of symbols that can be used to make strings, a collection of production rules that expand each symbol into some larger string of symbols, an initial "axiom" string from which to begin construction, and a mechanism for translating the generated strings into geometric structures. - from wikipedia