BL118 Datasheet, PDF (3/7 Pages) Radiometrix Ltd – Bi-directional low power RF Remote Control boards

LED Indications
The "blinking lights" on a BL118 look similar to a BD118, but the functions are actually very different (we
cannot leave an LED constantly "on", or it's 2mA current drain will dominate the unit power consumption)
Master LEDs
D1
D2
D3
Relay Activated
Regular Blink – In Lock
Short Blink – In Lock
Regular Blink – Loss of communication link
OFF - Loss of communication link
Slave LEDs
D1
D2
D3
A slave which has never achieved lock idles with all LEDs OFF
Relay Activated
OFF – In Lock
ON – Loss of communication link
Regular Blink – In Lock
OFF - Loss of communication link
The BL118 CPU
All current BL118 systems (so far) share the same data burst structure and coding scheme. The bit coding is
simple biphase, at approx 3600 bits per second. The burst is a 36mS long frame, incorporating 10mS of
preamble, a framing /sync sequence, an 8 bit address, an 8 bit data word and a checksum. To date no
BL118 uses any more than 1 bit of the data word, although in principle the whole word can be used, and it
would not be difficult to add extra words to the burst (at the cost of a longer burst)
In the basic master/slave BL118 these bursts are used within a 2 second frame. Each frame begins with the
master sending a burst, to which the slave replies. The timing permits 40mS for each transmission, and up to
50mS "listen" time on receive (these timings allow a good deal of timing slack). Throughout the rest of the
frame the hardware goes into sleep mode and draws no more than 10uA. With a 10mW BiM1 VHF module
this results in an average current consumption (relays off) of just under 1mA (a battery of 6 D cells will drive
such a unit for over two years).
The developed BL118 "multi-master" is a code version whereby a single master polls (up to) 16 slaves, by
cycling through the lower 4 bits of the address word (each slave has a unique 4 bit "ID" set on the lower 4
bits of the address DIP switch. The upper 4 bits still constitute a "global" address). Each poll operation
consists of a master transmission followed by a slave reply (as in the standard BL118) and all 16 such
operations occupy 1.44s of the 2 second frame. Slave unit current consumption is unchanged, but the multi-
master is understandably more hungry (around 16mA average for a unit fitted with a BiM1 VHF radio)
All slave outputs are commoned to the master input, while the master relay output is the "or" function of all
the slave inputs. In addition, the master will re-transmit an "activate" command in the frame following one
where any slave input was seen to be active (in this way it functions as a sort of system repeater)
In addition, once every frame the master outputs (via the JP7 auxiliary I/O pins) a stream of RS232 bytes (at
9600 baud) that report the input states of all the slaves (as received) and the presence or absence in system
of each slave.
Radiometrix Ltd
BL118 App boards
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