Control44 transmits a 6-byte burst, with 8 bits of preamble and 4 bits postamble. When firing up the
transmitter from cold Control44 puts in an extra 55ms especially for Narrow Band FM transmitter and
receiver requiring longer power-up to stable data time.
Figure 5: Push button transmission with 55ms power-up preamble
The large amount of sync code, address and checksum reduce the likelihood of false calling on noise to
an insignificant degree, while the breaking up of the data sequences with bit7 zeros is to reduce the
likelihood of the decoder mistaking particular sequences in the data for sync codes.
Differential Manchester encoding coverts the 0000 into 11001100 which is the bit pattern equivalent to preamble
required to settle adaptive data slicer in the RF receiver module.
Preamble =
Sync1 =
Sync2 =
DataA =
DataB =
Address =
Checksum =
11001100
this byte is not decoded.
10111111
111100(A7)(B7)
0(DA6-DA0)
Reserved for future use and custom variants
0(DB6-DB0)
0(A5-A0)0
sum of (DA7-DA0) + (DB7-DB0) + Adr(whole byte) truncated to 8 bits
This allows 6 bits of address and 2 data bytes per 60ms burst when 3.58MHz resonator is used.
Preamble
00000000000000
11001100
Sync1
10111111
Sync2
111100(DA7)(DB7)
Data A
0(DA6:DA0)
Data B
0(DB6:DB0)
Address
0(A5:A0)0
Check Sum
DA7:DA0+DB7:DB0
+A7:A0
Postamble
0000
Figure 6: Control44 data packet
In the following example, Control44 in Encoder mode is set with the following.
DB3
1
The Control44
transmitted as
slot.
.
Preamble
11001100
Radiometrix Ltd
DB2
0
DB1
1
DB0
0
A3
1
A2
0
A1
0
A0
1
will packetise the address and data into the following format. Reserved DataA is
00hex. Any custom variants requiring more than 8 bits of data will make use of this
Sync1
10111111
Sync2
11110000
DataA
00000000
DataB
00001010
Control44
Address
00010010
Checksum
00011100
Postamble
0000
page 4
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