ata5780 ATMEL Corporation, ata5780 Datasheet - Page 9

• Manufacturer Part Number: ata5780
• Description: Uhf Ask/fsk Receiver
• Manufacturer: ATMEL Corporation

3.4.6.2
Figure 3-3.
3.4.7
Figure 3-4.
9207BS–RKE–01/11
ID Scanning
Flexible Telegram Support Enabled (FTS = 1)
Principle of the Flexible Telegram
Possible ID Position in a Data Stream
WUP
Preburst
(8 Bit)
Preburst +
Startbit
(8 Bit)
Figure 3-2.
Whether a telegram is valid or not is decided using the bit check function and start bit as the
synchronization point. This telegram has less sustainability against noise. In order to guaran-
tee that the receiver will not be woken up very often by environmental noise the bit number to
be checked must be set to higher than 6.
This kind of telegram offers more sustainability for the communication link. This flexible tele-
gram consists of a wake-up pattern (WUP), a relatively short preamble and SFID preceding
the data stream. Between the WUP and preamble a space can be inserted in which no carrier
signal occurs. An optional stop bit may come at the end of the telegram. This is not absolutely
necessary because the end of the telegram is recognized when a Manchester code violation is
detected.
One novel feature of the receiver is ID scanning used in combination with RX buffer mode.
The receiver compares the received ID with the stored IDs in the EEPROM memory. Up to 18
IDs can be stored and each ID can be 4 bytes long at the most. The number of the IDs to be
activated can be set in the ID_EN control register. The ID length and the position of the ID in
the data stream can be specified in the IDx_CTRL control registers.
where the ID could be positioned in a data stream.
Space
1. Data
Byte
0
2. Data
Preamble
Byte
0
Principle of the Simple Telegram
Preamble
0
3. Data
Byte
0
0
4. Data
Byte
0
SFID
0
5. Data
0
Byte
Start
Bit
Atmel ATA5780 [Preliminary]
1
6. Data
0
Byte
1
7. Data
0
Byte
0
0
DATA
8. Data
Byte
0
Start ID Scanning
Start ID Scanning
Start ID Scanning
Start ID Scanning
0
9. Data
DATA
Byte
1
Figure 3-4
10. Data
Byte
IDxS
0
0
1
1
Stop
0
1
0
1
Bit
illustrates
9