User's Manual

2. RF Module Operation

WARNING: When operating at 1 Watt power output, observe a minimum separation distance of 2' (0.6m) between

modules. Transmitting in close proximity of other modules can damage module front ends.

Serial Communications

The XTend OEM RF Modules interface to a host device through a TTL-level asynchronous serial

port. Through its serial port, the module can communicate with any UART voltage compatible

device or through a level translator to any serial device (For example: RS-232/485/422 or USB

interface board).

UART Data Flow

Devices that have a UART interface can connect directly to the pins of the RF module as shown in

the figure below.

Figure 2-01. System Data Flow Diagram in a UART-interfaced environment

(Low-asserted signals distinguished with horizontal line over signal name.)

Serial Data

Data enters the module UART through the pin 5 as an asynchronous serial signal. The signal

should idle high when no data is being transmitted.

Each data byte consists of a start bit (low), 8 data bits (least significant bit first) and a stop bit

(high). The following figure illustrates the serial bit pattern of data passing through the module.

Figure 2-02. UART data packet 0x1F (decimal number "31") as transmied through the RF module

Example Data Format is 8-N-1 (bits - parity - # of stop bits)

The module UART performs tasks, such as timing and parity chec

king, that are needed for data

communications. Serial communications depend on the two UARTs to be configured with compati-

ble settings (baud rate, parity, start bits, stop bits, data bits).