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