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project:maerklin:system_control:start

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System Control

The System Control device, the main component, utilizes an ESP32 S3 Mini and a LCD display (128×64). The main purpose was to control the LEDs for the day/night cycle.

Introduction

The main microcontroller is an ESP32 S3 Mini. Its form factor is ideal for a small enclosure, and its processing power is sufficient for all tasks the control center requires. To enable user input, I created a custom PCB that holds the ESP32. This board features six tactile buttons, which are configured as a D-Pad (four directions), a select button, and a back button. The LCD displays a custom user interface via a dedicated library built on top of u8g2.

Extensibility

This system is built to be highly extensible. For this purpose, I designed a wireless system for indoor use based on Bluetooth LE. This decision was primarily driven by two factors: firstly, my desire to gain experience with BLE in a new project, and secondly (and more importantly), the aim to ensure independence from any specific MCU. Currently, I'm using an ESP32, which supports both Wi-Fi and BLE. However, I also plan to test other microcontrollers, such as those from the STM32 family (for instance, the STM32WB-Series, which offers strong BLE capabilities), to maintain this flexibility.

Technical Details

Each client advertises a specific service. The System Control scans all nearby BLE devices and filters for this service UUID. This service includes a 'capabilities' characteristic, which transmits the client's capabilities once the System Control enables notifications for this characteristic. This allows the System Control to build its UI dynamically, according to the received data.

More in-depth information will be provided once the MVP is complete.

Clients

The current list of the clients, which can be connected to the system:

Repository

You can find the source code and other in the git repository.

Software

TBD

Hardware

The KiCad files will be also in the git repository.

The schematics is very simple.

These are the latest PCBs, which I created. The manufacturing is done by JLCPCB, but it's an empty PCB, so I need to add the components to it later.

Mechanical

After creating the PCB, I needing a housing. So I started OnShape and imported the STEP file from KiCad. Some hours later and I got something useful.

But this was not the final result. I did some iterations and ended up with a really good housing. You can see the transparent render from OnShape, which are excellent.

I will not release the project files (because it's for my personal project), but maybe I recreate it someday in the future within FreeCAD and then I release it in the repository.

project/maerklin/system_control/start.1755988738.txt.gz · Last modified: by Peter Siegmund