Telit Wireless Solutions GL865 V3, Руководство пользователя

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HW User Guide
1vv0301018 Rev. 15 Page 38 of 72 2019-01-07
9. SERIAL PORTS
The serial port on the GL865 V3/V3.1 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)
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 V3/V3.1 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 V3/V3.1 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
IH
1.5V 1.9V
Input low level V
IL
0V 0.35V
Output high level V
OH
1.6V 1.9V
Output low level V
OL
0V 0.2V