Company Confidential
38
Raveon Technologies Corp.
10. Power Management
The RV-M8S has two ways to allow external devices to manage its power
consumption.
1. A digital input to control the DC power on or off.
2. The ATSM command to tell the device to change operational features putting
the device into a low-power mode (LPM).
10.1. A digital input
The IO pin 7 (Enable Pin) can be used to turn the device on or off. There is an
internal pull-up resistor that enables the RV-M8S if this pin is not connected to
anything.
If the Enable pin is pulled down to 0 volts, or at least below 0.7V, the Internal DC
power supplies in the device will turn off, and the device power consumption will get
very low. Typically below 1mA. The serial port an all device features will be
disabled. This is very similar to turning the DC power on or off, but for many digital
controllers, an open collector driver to digital out pin can be used to turn the radio on
or off without switching the DC, which save cost, time, and current spikes.
10.2. The ATSM command
The ATSM command manages sleep modes and power modes. When the
ATSM x
command
parameter
x
is set to:
0: The M8S will not go into LPM, regardless of the state of the DTR pin. This is the normal full-on
mode.
1: Enables the DTR input line controls the M8’s low-power operation. DTR can put the product into
LPM mode.
2: The modem is forced into a low-power mode (LPM), disabling the receiver and transmitter.
4: The receiver is off, reducing current draw. The transmitter will still transmit the data as it normally
does.
The LPM mode is a low-power mode, usually in the 20-30mA current range. The
CPU is still running, serial data still monitored, the GPS is still running if this feature
is used, but the receiver circuits are off, and the transmitter circuits are off. This
command can be issued to the device in the command mode or using WMX
messages to the device. Even in the LPM, the RV-M8S will process commands and
WMX messages.
