User's Manual

EMBER & RAYMARINE LIMITED - COMPANY CONFIDENTIAL
D619SP06 Issue 1.0 Page 9 D
O NOT DISTRIBUTE
3.4 Gateway (GW)
The GW is an always-powered device, which will serve requests initiated by Handheld
Controllers. This design uses PCB mounted antenna. Its role is to interact with the
SeaTalk bus caching data locally, in order to speed up remote transactions. Since the GW
is always powered it will be used as a relay / routing device. The embedded software running
on the network processor of the GW performs the following functions:
1. Control the EM2420 RFIC
2. Perform networking functions required by EmberNet
3. Act as protocol gateway, passing data through to the host using the REAP protocol
via a UART.
4. Provide a means of indicating registration activity
5. Manage and maintain all ‘binding’ information
6. The primary role of the Host Processor is to provide product functionality and not RF
networking capability
Details for each of these functions are as follows.
3.4.1 EM2420 Control
The software is responsible for all interactions between the network processor and the
EM2420 RFIC. The software performs power-on configuration of the EM2420, upper-level
MAC functions, SPI communications, and other necessary services.
3.4.2 EmberNet Networking
The software implements the EmberNet stack. It performs all basic messaging services
including origination, acknowledgement, and forwarding. It supports acknowledged
transmissions, route discovery / maintenance, device discovery, and network diagnostics.
3.4.3 Pass Through to the Host Processor
For communication between the network processor and the host microcontroller a simple
protocol, known as Raymarine to Ember Application Protocol (REAP) will be established. In
general this protocol simply takes advantage of the existing Raymarine protocol definition.