InfraRed Arbitrary Toolbox

iret is an acconym for InfraRed Arbitrary Toolbox.

The infrared arbitrary toolbox is a combination a a piece of MCU hardware with attached infrared sender and infrared receiver and a software/firmware installed on the MCU. implemented in Rust.

The whole project is splitted accross multiple repositories:

This repository - The documentation of the system (hardware and software)
Firmware - Embedded firmware specifically to Nucleo-STM32G071RB board
Manchester Code - Rust library to support manchester code encoding/decoding

This project is an experiment

To use mddoc for hardware/software technical documentation “as code”
To have a overarching repository that links several contributing repositories losely by a documentation as code
In software to turn an exploration project into something that can be reused according to the CRP (common reuse principle)

Motivation

Embedded software centric and Rust centric.

Reference Architecture

The reference architecture can act as blue print,

It encourages the software quality attributes:

No overhead: Only the amount of software that is really necessary

Improved maintenance less code to maintain
No runtime side effects

Open closed principle:

Common Reuse principle: Clean interfaces

Embedded HAL api is universal since software mapping abstraction is possible for established/ standardized hardware peripherals like i2c, spi, uart, gpio

Sample projects

An embedded project is not just software but hardware, and physical interfaces to the environment.
A close link needs to be maintained between between all those parts
SysML is one very valid approach for industrial grade project

For this kind or software centric playground documented sample projects are chosen to provide evidence for the software reference architecture applied.

Hardware

Requirements

No electronic design. no PCB design, no manufacturing including soldering shall be required
The Hardwaresetup shall be fixed, transportable and easy to bring up.
It should possible to disassemble the whole hardware without destroying the components.

Solution

Use a MCU COTS board with Arduino pin connectors.
Use Grove/Seeed shield to plug in peripherals

As MCU hardware STM nucleo board are picked because they are broadly used and there is excelent hal support for allmost all of them.

What we need is

A timer with ISR and an input pin for reading infrared telegrams
A timer with ISR and a pwm with output pin for writing telegrams
An uart to allow communication from remote
An optional display that shows arbitrary information like software version/variant, activity status

Nothing special, any Nucleo eval buard will do. Since a Nucleo-stm32G071RB is a already available by chance, we go for that.

BOM

No	Units	Description/Reference
1	1x	Nucleo-STM32G071RB
2	1x	Grove Baseshield V2
3	1x	Grove Infrared receiver
4	1x	Grove Infrared emitter
5	1x	Grove LCD RGB Backlight

Mechanical Fixing

Stackable base plate with holes, and assembled parts

The hardware setup

You can detect:

middle: Nucleo board with hocked up grove base shield
left side top: Infrared Reciever
left side button: Infrared Emitter
button: 16x2 LCD display
right side: UART to USB (CP2103) converter for convenience

Fits into an Euro Box 20cm x 30 cm x 7.5 cm for dust free storage

Euro box fit in

Software

Reference Architecture

Simple (RTOS free) embedded iot devices can use a reference architecture like

Embedded Reference Architecture

APP

The application the embedded device is running
Unit that implements top level of control and behavior
One application runs at a time
An application requires certain hardware resource available

Board

Maps the hardware resources provided by the board into the software
Implements Embedded HAL Interface for the specific board resources

Embedded HAL Interface

General hardware abstraction for common types of peripherals
like GPIO input, output, I2C, SPI, UART, ADC, DAC, CAN, timer
Is same for all processor architectures and boards

Biz Logic Component

Provides an certain well-specified business logic
encapsulated into a reusable component
It has no dependencies to hardware/board since it is independent upon any specific hardware
It might require certain hardware, to work with using the Embedded HAL Interface interface exclusively Thus, there is a dependency to the interface, but not to the board
Business Logic Components might implement some business hardware communication protocol of a chip connected via a standard HAL peripheral, it could be called a driver