Radiometrix Ltd, SpacePort Modem

page 6

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.

CTS

A single handshake line, CTS, controls the flow of data into the SPM. The serial receive buffer of

the SPM is 96 bytes deep. The CTS will be asserted by the SPM when the receive buffer hits

approximately 66% full. It is advisable to limit the number of characters sent to the SPM after the

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

buffer overruns in the SPM. The SPM will clear the CTS when the internal serial receive buffer

falls below 33% full.

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

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

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

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

Ω).

Asserting this pin low forces the SPM to startup with a default baud rate of 9600bps, 8 data, one stop and

not parity.

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

suitable resistor (10k

Ω).

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

when the modem is not required.

WAKE

power sleep mode.

resistor (10k

Ω).