User's Manual

GE866-DUAL Hardware User Guide
1VV0301051 Rev. 2 – 2014-04-07 7
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Mod. 0805 2011-07 Rev.2
9. Serial Ports
The serial port on the GE866-QUAD is the core of the interface
between the module and OEM hardware.
2 serial ports are available on the module:
• MODEM SERIAL PORT 1 (Main, ASC0)
• MODEM SERIAL PORT 2 (Auxiliary, ASC1)
9.1. Modem Serial Port
Several configurations can be designed for the serial port on
the OEM hardware, but the most common are:
• RS232 PC com port
• microcontroller UART @ 1.8V (Universal Asynchronous Receive
Transmit)
• microcontroller UART @ 3V or other voltages different from
1.8V
• microcontroller UART @ 5V or other voltages different from
1.8V
Depending from the type of serial port on the OEM hardware a
level translator circuit may be needed to make the system work.
The only configuration that doesn't need a level translation
is the 1.8V UART.
The serial port on the GE866-QUAD is a +1.8V UART with all the
8 RS232 signals. It differs from the PC-RS232 in the signal
polarity (RS232 is reversed) and levels. The levels for the
GE866-QUAD UART are the CMOS levels:
Parameter Min Max
Input level on any digital
pad when on
-0.3V +2.1V
Input voltage on analog
pads when on
-0.3V +2.1V
Level Min Max