This is my second RFLink hardware build. If you missed part 1, check it out here: How to make a $4 RFLink for 433MHz home automation!
The goal with this project was to build a small and neat RFLink dedicated to only be used as a gateway for 433MHz radios. But with full functionality, which supports the entire firmware.
What is RFLink?
It’s an 433MHz gateway designed to communicate with “standard” wireless -wallplugs, -switches, -weather stations and -temperature sensors. It’s built upon an Arduino (the full project uses an Arduino Mega) and is designed to be controlled by an home automation controller (eg Domoticz or Home Assistant). The receiver and transmitter is within the ISM free license band, is based on ASK-modulation and the protocol is OOK.
Link to the RFlink project. I’m not a developer/creator of the RFLink project, this is just my hardware contribution.
The hardware is based on a ATmega2560, because I wanted to be able to run the full Arduino Mega 2560 firmware. The RF-module is a “RTX MID 5V” from Aurel Wireless, it’s a 433MHz Transceiver. I used a ch340g as a USB to UART converter, beacuse it’s reliable and cheap.
I don’t think the hardware needs any more explanation, here is the schematic:
Some pictures of the build:
I forgot to add a 100nf capacitor between CH340G (DTR) to ATmega (reset). This is the Arduino flash-reset capacitor, which is used to reset the microcontroller and get it into bootloader mode, when you upload firmware to it. But this is no big deal for me, I flashed the ATmega with an external programmer trough the ISP header.
I’m happy with the result, it worked really good! As for now I have build 4 units, all are used 24-7.
But if you want to build one, remember to add a flash-reset capacitor!
You can find the schematic, pcb and documents on my github: