AX5243 datasheet(35/65 Pages) ONSEMI

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Circuit Description

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AX5243

Preamble L

FCS

Optional Data Block (optionally

repeated with FCS)

FCS

variable

8 bit

16 bit

48 bit

16 bit

8 – 96 bit

16 bit

For details on implementing a HDLC communication as well as Wireless M-Bus please use

the AXSEM RadioLab software and see the AX5243 Programming Manual.

RAW Modes

In Raw mode, the AX5243 does not perform any packet delimiting or byte

synchronization. It simply serializes transmit bytes and de-serializes the received bit-

stream and groups it into bytes. This mode is ideal for implementing legacy protocols in

software.

Raw mode with preamble match is similar to raw mode. In this mode, however, the

receiver does not receive anything until it detects a user programmable bit pattern

(called the preamble) in the receive bit-stream. When it detects the preamble, it aligns

the de-serialization to it.

The preamble can be between 4 and 32 bits long.

5.12. RX AGC and RSSI

AX5243 features three receiver signal strength indicators (RSSI):

1. RSSI before the digital IF channel filter.

The gain of the receiver is adjusted in order to keep the analog IF filter output

level inside the working range of the ADC and demodulator. The register

AGCCOUNTER contains the current value of the AGC and can be used as an RSSI.

The step size of this RSSI is 0.625 dB. The value can be used as soon as the RF

frequency generation sub-system has been programmed.

2. RSSI behind the digital IF channel filter.

The register

RSSI contains the current value of the RSSI behind the digital IF

channel filter. The step size of this RSSI is 1 dB.

3. RSSI behind the digital IF channel filter high accuracy.

The demodulator also provides amplitude information in the

TRK_AMPLITUDE

AGCCOUNTER and the TRK_AMPLITUDE registers,

a high resolution (better than 0.1dB) RSSI value can be computed at the expense

of a few arithmetic operations on the micro-controller. The AXSEM RadioLab

software calculates the necessary register settings for best performance and

details can be found in the AX5243 Programming Manual.

AX5243 Datasheet(PDF) 35 Page - ON Semiconductor

AX5243 Datasheet(HTML) 35 Page - ON Semiconductor

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