I have assembled the hardware of the gateway. The gateway is made from a TL-WR710N(EU) router and a Xmega header board I have previously designed. The XMEGA32A4U microcontroller serves as interface between the radio and the router since there is no hardware SPI available on the router. Currently the data transfer between the microcontroller and router is done with a USB-serial adapter because I need the original router serial port for debugging. Once the development is finished, I will switch to the router serial port. There is an additional serial connection between the microcontroller and PC to monitor the data transfers and debug.

The two antennas, router and NRF, are perpendicular to minimize coupling, as the router connects to my Wi-Fi to get online. Alternatively, I could use an Ethernet connection, but that requires an extra cable and limits the place where I can put the gateway.

I found a place for the gateway in a socket I never need to use.

Let the software development commence: two serial ports for debugging: