Raveon RV-M7, Техническое руководство

Страница: 18 / 67

RV-M7 Technical Manual
18
Serial out data comes out pins 3 and 7. Serial input data comes in via pins 4 and 8. Connect pin 5 to
earth ground.
4.8 Low Power Mode (LPM)
The M7 modem, has the ability to be put into a low power sleep mode (SM). In SM the modem draws
much less current from the DC input. In SM, the internal radio circuits in the M7 are disabled, as well as
certain current-consuming hardware circuits. The ability of the
M7 to go into LPM is set with a
configuration bit, using the ATSM command.
ATSM 1 configures the M7 to monitor the DTR input line, and enter the LPM mode whenever DTR is
negated. If the DTR signal is asserted, the M7 modem will operate normally.
The ATSM 2 command forces the M7 modem into the low-power mode. In the Low Power mode, the
M7’s radio circuits are off, but it will still respond to serial commands.
The ATSM 4 command forces the M7 modem into the low-power mode, but keeps the ability to
transmit data. In the Sleep Mode 4, the M7’s radio circuits are off, but it will still respond to serial
commands. It will turn its transmitter circuits on when there is data to send, send the data, and then
power the transmitter and receiver off.
The ATSM 0 command returns the M7 modem into the normal-operating mode with the receiver and
transmitter operational.
DTR negated means it is a negative voltage. A voltage less than zero volts applied to DTR will turn the
M7 off by putting it into LPM. To assert the DTR signal (turn the modem on), the DTR line must be high
(> 3V). DTR is an input to an RS-232 transceiver IC. It is ESD protected, and is safe for voltages from –
20V to +20V input.
The factory default value for the ATSM setting is 0 . When ATSM is a zero, the M7 will not ever enter the
LPM mode, and the DTR input signal is ignored.
5. User Serial Port Commands
5.1 Overview
The serial portion the RF modem is used to send and receive data over the air, as well as to configure
the RF modem. In normal operation, the user sends data into the TxD pin of the user port, and this data
is transmitted over the air. Received data from another RF modem is output to the user via the RxD pin
of the user port. This is the default operating condition of the RF modem. No special characters,
hardware control lines, or timing is required to operate the
M7 modem.
There is also a “Command Mode” used to program and configure the M7 . In the Command Mode, the
M7 modem accepts commands via the serial port TxD pin. The commands can be used to change
certain internal parameters of the M7 modem as well as to read-out the current configuration and
diagnostic statistics.
5.2 Command Mode
The M7 modem may be put into a “Command Mode”, by entering a sequence of three plus characters
(+++). To keep the M7 modem from unintentionally entering the Command Mode because of the +++