Radiometrix Ltd
Control44
page 4
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 =
11001100
this byte is not decoded.
Sync1 =
10111111
Sync2 =
111100(A7)(B7)
DataA =
0(DA6-DA0)
Reserved for future use and custom variants
DataB =
0(DB6-DB0)
Address =
0(A5-A0)0
Checksum =
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.
10111111
11001100
111100(DA7)(DB7)
0(DA6:DA0)
0(DB6:DB0)
DA7:DA0+DB7:DB0
+A7:A0
0000
00000000000000
Preamble
Sync1
Sync2
Data A
Data B
Check Sum
Postamble
0(A5:A0)0
Address
Figure 6: Control44 data packet
In the following example, Control44 in Encoder mode is set with the following.
DB3
DB2
DB1
DB0
A3
A2
A1
A0
1
0
1
0
1
0
0
1
The Control44 will packetise the address and data into the following format. Reserved DataA is
transmitted as 00hex. Any custom variants requiring more than 8 bits of data will make use of this
slot..
Preamble Sync1
Sync2
DataA
DataB
Address
Checksum Postamble
11001100
10111111 11110000 00000000 00001010 00010010 00011100
0000
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