Technical information

Chapter 2: Hardware Interface Description
November 15, 2008 G24-L Module Hardware Description 13
Power On/Off Operation
The G24-L power on and off process includes two primary phases, which are indicated at the
interface connector by the hardware output signals RESET_N and CTS_N.
The RESET_N signal indicates whether G24-L is powered on or off.
When this signal is enabled (low), G24-L is powered-off. When it is disabled (high), G24-L is
powered-on.
The CTS_N signal indicates the serial communications interface (UART) status. When this signal
is high, the G24-L serial interface is disabled. When it is low, the serial interface is enabled, and
G24-L is ready to communicate.
Important: Do not operate the G24-L out of its electrical or environmental limits. Refer to the
specifications chapter for details of these limits.
Important: The G24-LC model with battery charger will not turn-on unless all the battery
terminals are connected as required, and the battery voltage is above the minimum
operating level. Refer to “Battery Charger Interface” on page 47 for more
information.
Turning the G24-L On
When the G24-L power supply is stable above the minimum operating level and G24-L is
powered off, only the internal RTC timer is active.
When G24-L is turned on, by any of the methods described below, it will first perform an
automatic internal system-test, during which basic functions are verified. The system-test
duration is typically 800 milliseconds. When the system-test has completed G24-L resumes
normal operation.
During the internal system-test process G24-L may toggle several interface signals, which are
visible to the application. These signals do not represent any valid state or data, and should be
ignored by the customer application until the system-test has completed.
Turning the G24-L On Using ON_N
The ON_N input signal is set high, to VCC level, by an internal pull-up resistor whenever a
power supply is applied to G24-L. Therefore, it is recommended to operate this signal using an
open collector/drain circuit connection.
Asserting the ON_N signal low for a minimum of 500 milliseconds (0.5 seconds) and a maximum
of 1.5 seconds will cause the G24-L to turn-on.