It’s very, very intentional that ModularSensors uses that Atlas sensors only in I2C mode and I do not intend to change this. When using Atlas sensors in UART mode, each sensor must have an individually dedicated UART port. The Mayfly has exactly two hardware (processor implemented) UART’s – one dedicated to the computer/programming and the other dedicated to modem communication. It is possible to replicate UART functionality with “bit banging” libraries like AltSoftwareSerial or SoftwareSerial, but both of these have serious limitations. AltSoftwareSerial has acceptable quality communication but it is strictly limited to being used on pins 5 and 6 – which are spread on two different Grove ports on the Mayfly – and even then, monopolizes both of those pins. SoftwareSerial has poor communication quality, conflicts with every other library using interrupts including those absolutely required to wake the logger from deep sleep, and besides requires two dedicated pins. If the Atlas sensors are used as I2C devices, they can be connected to hardware already dedicated only to processor implemented I2C communication. This gives them the best quality communication, allows up to 126 devices on the same connection, and does not waste other data pins on the Mayfly. ModularSensors will continue to use I2C to support Atlas sensors.