This is one of my designs for an extendable general-purpose microcontroller.

It has the following features:

  1. Several configurable power supplies onboard: 3.3V, 5V, 10V and galvanically isolated 5V,
  2. 32-bit STM32Fx/STM32Lx microcontroller,
  3. Semtech LORA radio module working at 868 or 433 MHz,
  4. Galvanically isolated CAN interface,
  5. 4x analog inputs and 2x analog outputs with a configurable voltage range,
  6. Analog temperature sensor,
  7. Battery-powered real-time clock,
  8. Digital inputs and outputs broken out in the form of pin headers to connect to a daughter board.
  9. Phoenix Contact housing for DIN-rail or stand-alone applications,
  10. Powered by an external 9V-24V DC power supply.

The design has been tested in an application for monitoring and control of heat curtains. Below, you can see the daughter board for this application which provides five opto-isolated relays, two RS-485 connections, one RS-232 connection, two USB connections, an EEPROM and a temperature&humidity sensor (a Sensirion SHT21 in this case).

This is what the whole assembly looks like - a ZAR-1 (without the analog and CAN subsystems) plus the EXT1 board for heat curtain monitoring and control in a housing for DIN-rail:

The tests have been very successful and I am very happy with the functionality and flexibility of the design. The Semtech radio provides a nice connectivity between and over buildings on the 868 MHz bands, the RS-232 connection is used to transmit and receive data over a GPRS modem connection, the RS-485 communicate with ZAR-2 microcontrollers which deliver sensor data to ZAR-1. The relays control the heat curtain itself and a human user can monitor and control all devices connected over the LORA radio through the USB connection to a PC.

If you would like to know more about ZAR-1 or its possible applications, you can drop me a note at any time using the about page.