What’s Lua RTOS?

Lua RTOS is a real-time operating system designed to run on embedded systems, with minimal requirements of FLASH and RAM memory. Currently Lua RTOS is available for ESP32, ESP8266 and PIC32MZ platforms, and can be easilly ported to other 32-bit platforms.

Lua RTOS has a 3-layer design:

  1. In the top layer there is a Lua 5.3.4 interpreter which offers to the programmer all the resources provided by the Lua programming language, plus special modules for access the hardware (PIO, ADC, I2C, RTC, etc …), and middleware services provided by Lua RTOS (Lua Threads, LoRa WAN, MQTT, …).
  2. In the middle layer there is a Real-Time micro-kernel, powered by FreeRTOS. This is the responsible for that things happen in the expected time.
  3. In the bottom layer there is a hardware abstraction layer, which talk directly with the platform hardware.



Lua Threads

Lua Threads are probably the main key point of the Whitecat ecosystem programming model. Historically Lua has been a single-thread programming language, but Lua RTOS gives Lua the capacity to execute Lua functions concurrently  on independent tasks which shares the same Lua state.

The capacity to execute Lua functions in different threads, makes Lua RTOS programs more intelligible, so programs are written in a similar manner to the human thought.

Pthreads API

Lua RTOS is POSIX compliant. This feature, plus the fact that Lua RTOS provides a Pthread API, ensures that programmers can compile a lot of existing software with minimal changes.

Lua RTOS functionality matrix

Lua Threads yes yes yes
Pthread API yes yes yes
SSL yes not planned not planned
On-board editor yes not planned yes
Shell yes not planned yes
FAT file system yes not planned yes
SPIFFS file system yes yes yes
LoRa WAN, class A & B node yes planned yes
LoRa WAN, gateway yes not planned not planned
ADC yes not planned yes
SPI yes planned yes
UART yes planned yes
PIO yes yes yes
PWM yes planned yes
I2C yes planned yes
CAN yes not planned yes
Wi-Fi yes planned not planned
Ethernet yes not planned yes
Sensor yes not planned planned
Servo yes not planned planned
Stepper yes not planned yes