bitbaendiger / ledc

Really ugly opcode to control LED-Shows in constrained environments

ledc

Really ugly opcode to control LED-Shows in constrained environments.

LEGO has built an incredible ferris wheel, but it is even more awesome when you add some more visual effects to it.

The project that powers this repository features the following components:

• LEGO ferris wheel
• 12V DC Current
• 12V to 5V 6A Step-Down Voltage regulator
• A really huge electronic capacitor
• A Conrad C-Control IoT WiFi Board (comparable with an Arduino Nano, but with an ESP8266 added)
• 12x Pimoroni Mote APA102 RGB LED-Strip

As the Arduino Nano is very limited with space there was a need to stick LED-Shows into a format that consumes less memory - so ledc was born.

ledc introduces something assembler-like to execute certain "draw"-operations on LED-Strips. Each instruction is stuffed into a 32-bit word while there are 15 instructions (4 bit of instruction, 28 bit parameters).

There is one special "meta-instruction" SETCOLOR that actually has a 3-bit instruction and 29 bit for parameters. This is very ugly but needed if you want to use the whole set of features of an APA102-LED. At some places in code this is referenced as SETCOLOR, some other places use SETCOLOR0 and SETCOLOR1 for this.

The virtual-machine here is capabale of driving 16 LED-Strips and has up to 16 registers to store things in background. You may also define up to 16 groups of LED-Strips and registers that could be controlled using normal instructions as you would control a single LED-Strip or register.

Assembler

Instruction	Parameter	Description
SETCOLOR	Brightness, Red, Green, Blue	Set the current color to draw
SETDEST	Destinaiton	Set the current destination for drawing
SETS	Start, Length	Set color for series of pixels on current destination
SETI	Index1 ... Index6	Set color for pixels by their index
COPY	Source, Destination, Start, Length, Offset	Copy set of pixels from source to destination, shifting by offset
MIRRORS	Source, Destination, Length	Mirror an entire strip to a set of other strips
SHIFTR	Start, Length	Shift all of LED-Strips contents to the right
GROUPADDS	Group, Start, Length	Append a series of LED-Strips or registers to a group
GROUPADDI	Group, Index1 ... Index3	Append given LED-Strips or registers to a group
FRAME	Wait	Display the changes on the LED-Strips and Wait
GOTO	Label	Jump to a given label and continue execution from there on

See shows/ for example programms as Assembler-Code and in compiled format.

Compiler

There is a small compiler written in PHP located in compiler/. It's a CLI-Script that is invoked in the way

php led-compile.php {path-to-led-programm}

It produces an .ledc-file that is suitable for upload to the Arduino-Interpreter.

Emulator

There is an Emulator to run ledc-programms via Javascript in HTML located in emulator/.

Interpreter

The actual programm that executes ledc-code and creates the magic may be found in interpreter/. It's a small arduino-project that implements the interpreter and drives the APA102-LED-Strips using Software-SPI.

All LED-Strips are controlled in parallel - you'll need (Number of Strips + 1) GPIO-Pins to drive the LED-Strips, one GPIO per Strip for Data and one GPIO as clock connected to all Strips.

The programm expected all GPIO-Pins to be populated in ascending order, e.g. first strip at GPIO 3, second strip at GPIO 4, etc.. But you may group strips into up to four banks of LED-Strip-Connectors. You'll find some #define's for this on the code.

Copyright & License

Copyright (C) 2017 Bernd Holzmüller

Licensed under the GNU General Public License v3.0 (GPL). This is free software: you are free to change and redistribute it. There is NO WARRANTY, to the extent permitted by law.