3.1.2

Supported Telegrams

3.1.2.1

Telegram Structure

The ATA8710 supports the transmission of a wide variety of telegrams and protocols. Generally, no special structure

is required for a telegram to be transmitted by the ATA8710. However, designated hardware and software features

are built-in for the blocks depicted in the following figure. Therefore, using this structure or parts of it can increase the

robustness of the broadcast.

Figure 3-2. Telegram Structure

Desync

Preamble

Data Payload Checksum Stop Sequence

Desync:

The de-synchronization (Desync) is usually a coding violation with a length of several symbols that should provoke

a defined restart of the receiver. The use of a de-synchronization leads to more deterministic receiver behavior,

reducing the required preamble length, which can be favorable in timing-critical and energy-critical applications.

Preamble:

The preamble is a pattern sent before the actual data payload to synchronize the receiver and provide the starting

point of the payload. A very regular pattern (for example, 1-0-1-0...) is recommended for synchronization (“wake-up

pattern, WUP”) while a unique, well-defined pattern of up to 32 symbols is required to mark the start of the data

payload (“start frame identifier, SFID” or “start bit”). The WUP is also called a pre-burst. In polling scenarios, the WUP

can be tens or hundreds of ms long.

Data Payload:

The data payload contains the actual information content of the telegram. It can be NRZ or Manchester-coded. The

length of the payload is application-dependent, typically 1-64 bytes.

Checksum:

A checksum can be calculated across the data payload to verify that the correct data is received. A typical example

is an 8-bit CRC checksum. Up to 255 data bits at the beginning of the payload can be excluded from the CRC

calculation.

Stop Sequence:

The stop sequence is a short data pattern (typically 2 to 6 symbols) to mark the end of the telegram. A coding

violation can prevent additional (non-deterministic) data from being received.

3.1.2.2

NRZ and Manchester Coding

In this document:

• Data bit – Represents the smallest unit of binary data being communicated

• Data bit rate – The rate at which data bits change value

• Symbols – Sub-unit of binary data bit. Used when multiple symbols define a data bit

• Symbol rate – The rate at which symbols change value

The ATA8710 supports the following coding methods:

• Manchester coding – Implements two symbols per data bit. A symbol transition from ‘0’ to ‘1’ is defined as a ‘1’

data bit, and a symbol transition from ‘1’ to ‘0’ is defined as a ‘0’ data bit when following the Manchester coding

convention specified in IEEE 802.3. For more details, see the following figure.

• Non-return-to-zero (NRZ) coding – Is a straightforward implementation, that is, one symbol represents one bit.

ATA8710

System Functional Description

and its subsidiaries

Advance Information Datasheet

DS70005477A-page 13