User's Manual

GL865-DUAL/QUAD V3 Hardware User Guide

1vv0301018 Rev.7 – 2013-10-30

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Reserved. Page 38 of 78

Mod. 0805 2011-07 Rev.2

9. Serial Ports

The serial port on the GL865-DUAL/QUAD V3 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 GL865-DUAL/QUAD V3 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 GL865-DUAL/QUAD V3 UART are the CMOS levels:

Absolute Maximum Ratings -Not Functional

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

Operating Range - Interface levels (1.8V CMOS)

Level Min Max

Input high level V

1.5V 1.9V

Input low level V

0V 0.35V

Output high level V

1.6V 1.9V

Output low level V

0V 0.2V