Hardware Guide
Table Of Contents
- Introduction
- 2. Overview
- 3. GE865 Mechanical Dimensions
- 4. GE865 module connections
- 5. Hardware Commands
- 6. Power Supply
- 7. Antenna
- 8. Logic level specifications
- 9. Serial Ports
- 10. Audio Section Overview
- 11. General Purpose I/O
- 11.1. GPIO Logic levels
- 11.2. Using a GPIO Pad as INPUT
- 11.3. Using a GPIO Pad as OUTPUT
- 11.4. Using the RF Transmission Control GPIO4
- 11.5. Using the RFTXMON Output GPIO5
- 11.6. Using the Alarm Output GPIO6
- 11.7. Using the Buzzer Output GPIO7
- 11.8. Indication of network service availability
- 11.9. RTC Bypass out
- 11.10. External SIM Holder Implementation
- 12. DAC and ADC section
- 13. Mounting the GE865 on your Board
- 14. Packing system
- 15. Conformity Assessment Issues
- 17. Document History
GE865 Hardware User Guide
1vv0300799 Rev.15– 2012-04-23
Reproduction forbidden without Telit Communications S.p.A. written authorization - All Rights Reserved page 44 of 77
9. Serial Ports
The serial port on the GE865 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
@ 2.8V - 3V (Universal Asynchronous Receive Transmit)
• microcontroller UART
@ 5V or other voltages different from 2.8V
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 2.8V UART.
The serial port on the GE865 is a +2.8V UART with all the 7 RS232 signals. It differs from the
PC-RS232 in the signal polarity (RS232 is reversed) and levels. The levels for the GE865
UART are the CMOS levels:
Absolute Maximum Ratings -Not Functional
Parameter
Min
Max
Input level on any digital
pad when on
-0.3V
+3.1V
Input voltage on analog
pads when on
-0.3V
+3.1V
Operating Range - Interface levels (2.8V CMOS)
Level
Min
Max
Input high level V
IH
2.1V
3.1 V
Input low level V
IL
0V
0.5V
Output high level V
OH
2.2V
3.1V
Output low level V
OL
0V
0.35V