IO - Interface Connectivity (Webserver, MQTT)
A practical use was also quickly found—namely, the remote control of parts of the amateur radio setup.
IO - Interface Connectivity (Webserver, MQTT)
Nowadays, many electronic devices have access to the internet, and they can be operated or controlled through it. Physically, these devices are usually connected to the home network via LAN or Wi-Fi. So there is reason to take a closer look at this topic.
A practical use was also quickly found—namely, the remote control of parts of the amateur radio setup. For this, I need digital inputs and outputs, as well as analog inputs and outputs. A “simple” serial interface would also be quite useful.
After a bit of research, I decided on the following solution:
- for WLAN, an ESP32-C5 is a good choice.
- for LAN, an STM32 and a W5500 make a good combination.
- and as a USB class HID is sufficient, so also a STM32 is good.
I designed the actual I/O interfaces as a separate circuit board (Basis IO-Board). This allows switching between Wi-Fi, LAN, or USB simply by replacing (plug) the microcontroller board. Everything together, fits into a standard DIN rail plastic enclosure. All external interfaces are galvanically isolated from each other and from the MCU board. The external connections are routed to plug-in or screw terminals. The power supply is nominal 24 V DC.
All variants have the following features in common:
Operation via a web browser, or in the case of USB, a web-like interface.
All parameters (network settings, labels, etc.) can be individually modified and are permanently stored.
Serial number and MAC address are generated from the globally unique IDs of the MCUs.
Additional USB-C port (reversible connector) for firmware updates.
Status LED for operating state and the condition of the digital I/Os
MQTT runs in parallel with the web server and uses the same IO data/labels (only WLAN and LAN version).