TDA5235 Datasheet, PDF (66/259 Pages) Infineon Technologies AG – Enhanced Sensitivity Double-Configuration Receiver with Digital Baseband Processing

TDA5235
Functional Description
Message ID Scanning is aborted immediately by the Master FSM, if symbol
synchronization is lost or an EOM (End Of Message) is detected.
Example:
Start Selection: 00010001b
Number to scan: 00b, 01b, 10b, 11b
FSYNC
Bit 0 1 2
Number To Scan =00b
Number To Scan =01b
Number To Scan =10b
Number To Scan =11b
17 18
Byte0
Byte0
Byte0
Byte0
23 24 25 26
Start MID Scan
B y t e1
B y t e1
B y t e1
31 32 33 34
Byte2
Byte2
39 40 41 42
Byte3
47 48 49
Figure 37 MID Scanning
The starting position in this case is Bit 17. Depending on the number to scan, the
corresponding number of bytes is compared with the stored MIDs.
2.4.8.8 RUNIN, Synchronization Search Time and Inter-Frame Time
The functionality of the Digital Baseband Receiver is divided into four consecutive data
processing stages; the data filter, clock and data recovery, data slicer and frame
synchronization unit. The architecture of the Digital Baseband Receiver is optimized for
processing bi-phase coded data streams.
The basic structure of a payload frame is shown in Figure 38. The protocol starts with a
so called RUNIN. The RUNIN with the minimum length of four bi-phase coded symbols
is used for internal filter settling and frequency adjustment. The TSI (Telegram Start
Identifier), which is used as framing word, follows the RUNIN sequence. The payload
contains the effective data. The length of the valid payload data is defined as the length
itself or additional criteria (e.g. loss of Sync).
Please note that almost all transmitted protocols send a wake-up sequence before the
payload frame (see also Figure 72). This wake-up sequence allows a very fast decision,
whether there is a suitable message available or not. Further details on this topic can be
gained from Chapter 2.6.1.5 and Chapter 2.4.8.5.
Data Sheet
66
V1.0, 2010-02-19