1. Design a simple LiDAR module that is relatively easy to understand.
2. Use as many COTS (commercial-off-the-shelf) electronic components as possible.
3. The software must be easy to modify without a complicated IDE.
4. Mechanical parts must be 3D printable.
5. Optical components must be available at a reasonable price.
The Unruly is a time-of-flight LiDAR that uses a pulsed laser diode (PLD) to generate a flash of light, an avalanche photodiode (APD) to detect the return signals and a high speed timer (TDC) to measure the return time. So far:
The measuring range can be adjusted to over 100m on natural surfaces and 250m on reflective surfaces, outdoors in bright sunlight.
The resolution can be configured down to 1 cm.
The measuring rate is up to 1000 readings per second or maybe more
The Unruly use of open source hardware: ItsyBitsy M4 Express
The Unruly uses existing open source hardware as a starting point, the Adafruit ItsyBitsy M4 Express. This is a small microcontroller board with a SAMD51 processor, extra flash memory and almost nothing else. Why, you are asking, have you chosen such a basic controller board to manage the complicated hardware of a LiDAR? Well, my wife likes how small it is and it has a cute name. Of course it helps that the SAMD51 runs at 120MHz and has a bunch of really interesting peripherals.
The Unruly use of open source software: CircuitPython
Another reason for choosing the ItsyBitsy M4 Express board is that it can run a version of the programming language Python called CircuitPython. This is by far the least likely language to be used in a high speed embedded system, especially one that needs to work at the speed of light. Python is an interpreted, high level language that manages variables and memory in a vague, non-specific way. There are only a few APIs and these do stuff that is no use to a LiDAR.
But CircuitPython is easy to write, easy to read and can be programmed without an IDE by using a basic text editor. This seems like a good enough reason to use it.
Stop breadboarding and soldering – start making immediately! Adafruit’s Circuit Playground is jam-packed with LEDs, sensors, buttons, alligator clip pads and more. Build projects with Circuit Playground in a few minutes with the drag-and-drop MakeCode programming site, learn computer science using the CS Discoveries class on code.org, jump into CircuitPython to learn Python and hardware together, TinyGO, or even use the Arduino IDE. Circuit Playground Express is the newest and best Circuit Playground board, with support for CircuitPython, MakeCode, and Arduino. It has a powerful processor, 10 NeoPixels, mini speaker, InfraRed receive and transmit, two buttons, a switch, 14 alligator clip pads, and lots of sensors: capacitive touch, IR proximity, temperature, light, motion and sound. A whole wide world of electronics and coding is waiting for you, and it fits in the palm of your hand.