The most common interfaces such USB, UART, I2C, SPI, digital inputs/outputs are available on board. But there are no limits on the Helios capabilities: LoRa, ZigBee, movement sensing, GPS..., all those are available on standard rhomb modules. The only thing you need is connect them on the corresponding slots. Furthermore, several microcontrollers of differets manufacturers are compatibles thanks to Rhomb.io modular technology. If there is a need for more processing power: you don't need to replace the Helios, the only thing you have to do is replace the master module for another more powerful. Helios board is fully compatible with Arduino and all its shields with extra features..
Please check the Info in our wiki.