A d v a nce d I n fo rm a t i o n

8

Linear Technology / Dust Networks

Eterna Datasheet

Figure 6

UART Mode 4 Transmit Flow Control

For details on the timing of the UART protocol, see section 8.9 (UART AC Characteristics).

2.5.3

CLI UART

The Command Line Interface (CLI) UART port is a two wire protocol (TX and RX) that operates at a fixed 9600 baud rate

with one-stop bit and no parity. The CLI UART interface is intended to support command-line instructions and response

activity.

2.6

Autonomous MAC

Eterna was designed as a system solution with the objective of providing a reliable, ultra-low power, and secure network. A

reliable network capable of dynamically optimizing operation over changing environments requires solutions that are far too

complex to completely support through hardware acceleration alone. As described in Section 2.2, proper time management is

essential for optimizing a solution that is both low power and reliable. To address this solution Eterna includes the

Autonomous MAC, which includes hardware support for controlling all of the time-critical radio operations. The

Autonomous MAC provides two benefits: first, preventing variable software latency from affecting network timing and

second, greatly reducing system power consumption by allowing the CPU to remain inactive during the majority of the radio

activity. The Autonomous MAC, unique to Eterna, provides software-independent timing control of the radio and radio-

related functions, resulting in superior reliability and exceptionally low power.

2.7

Security

Network security is an often overlooked component of a complete network solution. Proper implementation of security

protocols is significant in terms of both engineering effort and market value in an OEM product. Eterna system solutions

provide a FIPS-197 validated encryption scheme, and goes further, providing a complete set of mechanisms to protect

network security. Eterna includes hardware support for electronically locking devices, thereby preventing access to Eterna’s

flash and RAM memory. This lock-out feature provides a means to securely unlock a device should support of a product

require access. For details see 040-0109 Design Specific Configuration Guide.

2.8

Temperature Sensor

Eterna includes a calibrated temperature sensor on chip. The temperature readings are available locally through Eterna’s

serial API, in addition to being available via the network manager. The performance characteristics of the temperature sensor

can be found in Section 8.6.

2.8.1

Radio Inhibit

The RADIO_INHIBIT digital interrupt enables an external controller to temporarily disable the radio software drivers (for

example, to take a sensor reading that is susceptible to radio interference). When RADIO_INHIBIT is asserted the software

radio drivers will disallow radio operations including clear channel assessment, packet transmits, or packet receipts. If a radio

event is in progress radio inhibit will take effect after the present operation completes. For details on the timing associated

with RADIO_INHIBIT, see Section 8.12.