BIM-418-10 Radiometrix, BIM-418-10 Datasheet - Page 10

• Manufacturer Part Number: BIM-418-10
• Description: Low Power UHF Data Transceiver Module
• Manufacturer: Radiometrix

Sending and Receiving Digital data
The BiM contains no data coding or decoding functions. These must be provided by the external
controller, usually a single chip microprocessor, e.g. Arizona Microsystems PIC, Motorola MC68HC05 or
similar. Alternatively a dedicated protocol controller such as CML's FX909 or Echelon's Network chips
will work well.
The Radiometrix RPC-000-SO Radio Packet Controller IC provides all the processor intensive low-level
packet formatting and data recovery functions required in a high speed bi-directional data link/network.
The RPC-418-40 and RPC-433-40 provide a self-contained UHF radio port for a host micro controller.
The board combines a BiM transceiver and a RPC packet controller. (Data available on request.)
A pair of BiM transceiver’s will transmit direct serial data applied to the TXD input and reproduce
direct serial data at the RXD output of receiving BiM. The BiM may also be used with linear data e.g.
from modem IC's (see test circuit for linear biasing of TXD input).
Direct Digital, TXD > RXD at 5V CMOS Levels
The data path through a pair of BiM's is AC coupled. This places 3 basic constraints that any serial code
must satisfy for reliable transfer.
1. Pulse width time
2. RX settling time
3. Mark/Space ratio
Any serial data waveform satisfying the above criteria will pass reliably through a pair of BiM's.
Radiometrix Ltd, BiM Data Sheet
figure 7: typical microcontroller interface
time, T, between any 2 consecutive transitions in the serial code must
satisfy: 25µs < T < 2ms
preamble to be transmitted before the data at the RXD output may be
considered reliable. Increasing this time to 5ms will give increased
immunity to RF interference.
Mark:Space averaged over any 4ms period. The slicer will tolerate sustained
asymmetry up to 30/70 (either way), however, this will result in up to
increased in pulse width distortion and a decreased noise tolerance.
The receiver base band bandwidth and the AC coupling determines that the
The AFC and data slicer in the receiver require at least 3ms of '10101010'
The data slicer in the receiver is optimised for data waveforms with 50:50
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