Radiometrix Ltd.

UHF FM Radio Packet Modem

page 5

protocol settings are 8 data bits, no parity and 1 stop bit (8n1). The baud rate setting for the serial interface is

user settable from 600bps to 115200bps.

TXD

Data from the connected host (DTE) is received by the RPM3B through TXD pin.

CTS

A single handshake line,

CTS, controls the flow of data into the RPM3B. The serial receive buffer of

the RPM3B is 96 bytes deep. The

CTS will be asserted High (VCC) by the RPM3B when the receive

buffer hits approximately 66% full. It is advisable to limit the number of characters sent to the RPM3B

after the

CTS control line is asserted. This will help to reduce the possibility of lost data due to internal

buffer overruns in the RPM3B. The RPM3B will clear the

CTS when the internal serial receive buffer

falls below 33% full.

RXD

Upon the RPM3B receiving data from a remote unit, the received data is sent to the connected host

(DTE) device through the RXD pin..

Configuring the RPM3B is accomplished by using a built-in command line configurator. The configurator is

input is checked while the RPM3B starts up from either power on or reset.

The Setup pin may either be driven by the host (recommended) to enable host controlled configuration

Asserting this pin low forces the RPM3B to start-up with a default baud rate of 9600bps, 8 data bits, one stop

and no parity.

9600bps. This is ideal if the serial baud rate has been forgotten or incorrectly set.

pull-up resistor (10kΩ).

RPM3B and prevents it from sending or receiving any data. It is a method for conserving power when the

modem is not required.

WAKE

sleep mode.