CMOSTEK CMT2157AW, Manual

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CMT2157AW
Rev 0.8 | Page 18/31 www.hoperf.com
Preamble
16 symbols
Address (Sync ID)
configurable 1-32 bits
D0
1 bit
D1
1 bit
D2
1 bit
D3
1 bit
CRC
8 symbols
Head_N
32 symbols
Figure 14. 1920 Normal Packet Structure
Study Packet
The study packet is used for the receiver to learn the Sync ID from the CMT2157AW in order to pair the two devices. It
contains an optional Preamble, a 32-symbol Head_S, a Sync ID and an 8-symbol CRC.
Preamble
(Optional)
16-symbol
CRC
8-symbol
Head_S
32-symbol
Address (Sync ID)
configurable 1-32 bits
Figure 15. 1920 Study Packet Structure
Bit Format
In 1920 packet, a single bit can be constructed (encoded) by 3, 4, 5 or 6 symbols. The user can select the desired value of the
“Bit Format” parameter on the RFPDK. Please note that only the Sync ID field and the D0, D1, D2, D3, D4, D5, D6 have the
unit of “bit”.
2 SYM 2 SYM 1 SYM 1 SYM
Bit 1 Bit 0
1 SYM 1 SYM 3 SYM 3 SYM
Bit 1 Bit 0
3 SYM 2 SYM
Bit 1
2 SYM 3 SYM
Bit 0
2 SYM 1 SYM
Bit 1
1 SYM 2 SYM 1 SYM 1 SYM
Bit 0
1 SYM 3 SYM
3 Symbols/Bit
4 Symbols/Bit
5 Symbols/Bit
6 Symbols/Bit
Figure 16. 1920 Bit Format Options
5.7.2 1527 Packet Structure
Two types of packet structures are supported for 1527 format: Normal Packet and Study Packet. The following configurable
parameter is shared by the two structures.
Table 14. Configurable Parameters in 1527 Packet
Parameter Descriptions Default Mode
Address (Sync ID)
Value
The range of the Sync ID value is from 0 to 2
20
-1. This is
because the Sync ID Length is fixed at 20 for 1527.
0
Basic
Advanced
In the traditional 1527 format, 8 OSC clocks are equal to 1 LCK, 4 LCK are equal to 1 symbol. By using the CMT2250AW
pairing with CMT2157AW, the user does not need to adjust the OSC to determine the symbol rate, because the symbol rate is
directly programmed. The Bit Format is fixed at 4 symbols (16 LCK) per bit.