This document details the interface to the Link Labs LTE-M Module. This interface consists of a point-to-point serial communications protocol, intended to be used over a UART and GPIO connection to the Link Labs LTE-M modules. This connection is referred to as the “Host Interface”. A simplified block diagram is shown below.
The UART connection utilizes a Master/Slave protocol, with the Link Labs LTE-M module always running in slave mode. The protocol allows for data exchanges to be initiated by both master and slave devices, although the initiation mechanism is different.