This DIY soldering kit adds an RS485 interface to an ATMEGA328 to connect to different RS485 sensors and provide averaged data via a UART interface. It is designed to be easy to use, provide correct voltage levels and be energy efficient.

"Why do you need that?", you ask....

I had been wanting to use an industrial soil moisture sensor for a simple project. This device was only available as an RS485 device. So I ordered that - it then took days of head scratching to sort basic communication with the device. This unit is meant to simplify reading of averaged data from RS485 sensors and make it easy to get that data into your project via a simple serial request/reply set of commands.

The other issue with a lot of the RS485 sensor is that they need higher voltages supplied (such as 12V or even 24V DC). So on this interface board I added a DC-DC step up converter to power the sensor.

I was also concerned with energy consumption (my project was battery based). If I was to leave the DC-DC converter running all the time then my battery would run down very quickly. So I added control of the power to the sensor, so that I can power up, take the readings then power down. This saves a huge amount of energy (well, proportional to my battery size).

The problem with measuring sensors with values that change relatively quickly is that they constantly need to be checked. This requires a bit of microcontroller time and processing. This unit is designed to solve that.

Wire up your sensor. Power the unit up. Then it will save the averaged data for you. You can then get hold of the data through serial requests and process as you need.

For my application I wrote some simple code to interface to an ESP32 data logger, which sleeps most of the time. It wakes up, talks to the sensor, gets the data it needs, then goes back to sleep, knowing the sensor is always monitoring.

I have written configurable firmware for a few different sensors to remove the need for monitoring pulses/dealing with RS485 requests/getting sensor data and averaging the sensor data.

It provides a more easy to use UART serial interface to obtain averaged data the sensor. Data can be 1s,10s, 1min, 10min and 1hr averaged data along with the maximum and minimum values within that time period. 

It also provides a controlled step-up converter (if needed) to power the attached sensor, which can step up the supply voltage (3.3V or 5V DC) to the voltage required by the sensor, such as 12V or 24V. This can be switched off between sensor reads to save energy from the battery.

There is also an I2C interface to add additional sensors, such as a temperature or humidity.

Note: This is a soldering kit and requires construction. It also requires some knowledge of firmware and you must develop your own code to read the data from this interface board and display or record it.

Note: It requires another micro-controller unit to request and store the data from the sensor interface board.

You must upload the correct firmware for your sensor, please check the GitHub for examples:

https://github.com/curiouselectric/SensorInterfaceBoard

Instructions for building this interface are available here.

The design files for this PCB, along with these instructions, is available from the GitHub repository for this board:

https://github.com/curiouselectric/RS485InterfaceBoard

If you would like specific firmware uploaded to the microcontroller IC then please let me know. I can upload firmware for any of the RS485 sensors that we sell (Soil Moisture & Pyranometer PYN20 at the moment).