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GE866-QUAD Hardware User Guide
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Page 44 of 82
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
Input high level V
IH
1.5V
1.9V
Input low level V
IL
0V
0.35V