CMOSTEK CMT2250A, Configuration Manuallines

Page: 20 / 31

AN118
Rev 1.1 | Page 20 / 31
www.cmostek.com
In the below explanation (also on the RFPDK), the packet structural diagrams show all the elements in the packets, as well as the
available options corresponding to each element.
Furthermore, some elements in the packet are measured in the unit of “symbol”, while some of them are measured in the unit of
“bit”. For those which have the unit of “bit”, one “bit” is constructed (encoded) by several “symbols”. In the figures, “SYM”
represents the word “symbol”.
5.1.1 1920 Normal Packet Structure
The normal packet is used to control the data pins. It contains an optional Preamble, a 32-symbol Head_N indicating the current
packet is a Normal packet, a Sync ID, 4-bit Data and an optional 8-symbol CRC.
Figure 24. 1920 Normal Packet Structure
Table 11. Configurable Parameters in 1920 Packet
Parameter Descriptions Default Mode
Preamble
The size of the valid preamble, the options are: None,
8-symbol, 16-symbol, 24-symbol or 32-symbol.
None
Basic
Advanced
Address (Sync ID)
Length
The range of the Sync ID Length is from 1 to 32 bits. 32 bits
Basic
Advanced
Address (Sync ID)
Value
The value of the Sync ID has the range from 0 to 2
Length
-1. 0
Basic
Advanced
CRC
The CRC validation increases the reliability of the
reception. The options are: Enable or Disable.
Disable
Basic
Advanced
 Preamble
The pattern of a 16-symbol preamble is shown below:
1
SYM
1
SYM
1
SYM
1
SYM
1
SYM
1
SYM
1
SYM
1
SYM
1
SYM
1
SYM
1
SYM
1
SYM
1
SYM
1
SYM
1
SYM
1
SYM
Figure 25. 1920 16-symbols Preamble Pattern
Typically, if the WOR (Wake-On Radio) function is turned on, the preamble is used to extend the receive time. Please see
Chapter 3.3.2 for considerations of using the WOR function in the application of “Extended by Preamble”.

Head_N
The user does not need to control the Head_N because it is automatically generated by the CMT2150A and recognized by the
CMT2250A. The pattern of Head_N is shown below.
2
SYM
2
SYM
2
SYM
2
SYM
1
SYM
1
SYM
1
SYM
1
SYM
2
SYM
1
SYM
1
SYM
2
SYM
2
SYM
2
SYM
2
SYM
1
SYM
1
SYM
1
SYM
1
SYM
1
SYM
1
SYM
1
SYM
1
SYM
Figure 26. 1920 Head_N Pattern