Enfora Enabler II-G Assisted GPS Modem Integration Guide VBAK had been tested in the above scenarios and does not contribute to leakage. It will properly
provide backup power to the RTC clock.
6.6.6. Serial Interface for UART and GPS
The modem provides a standard 16550 UART serial interface to the host. The data interface
operates at CMOS level. The Enabler II-G A-GPS module is designed to be used like a DCE
device or can also mux the serial port to share the port between serial data and GPS NMEA
information. Below are descriptions of the various serial architectures used to interface with
the GPS chipset integrated into the module.
This serial interface data may contain 7 or 8 data bits, 1 or 2 stop bits, even/odd/no parity bits.
The baud rate may be adjusted to 75, 150, 300, 1200, 2400, 4800, 9600,19200, 38400, 57600,
or 115200 bits per second.
Default settings are 8 data, 1 stop, no parity, and 115200 baud. DTR may be used to force the
modem into AT command mode from online data mode (See AT Command Document,
command AT&D). RTS and CTS may be used for hardware handshaking. DSR is always
active (connected to ground) while the modem is on. RING may be used to alert the host to a
variety of incoming calls.
For a minimal implementation, connect RxData and TxData to the COM port serial data lines,
connect DTR and RTS to GND.
The electrical characteristics for the I/O lines are the same as the General Purposes
Input/Output (GPIO) lines.