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 49 of 77
5V UART level translation
If the OEM application uses a microcontroller with a serial port (UART) that works at a voltage
different from 2.8 - 3V, then a circuitry has to be provided to adapt the different levels of the
two set of signals. As for the RS232 translation there are a multitude of single chip translators.
For example a possible translator circuit for a 5V TRANSMITTER/RECEIVER can be:
TIP:
Note that the TC7SZ07AE has open drain output; therefore the resistor R2 is mandatory.
NOTE:
The input lines working at 2.8VCMOS can be pulled-up with 47KΩ
In case of reprogramming of the module has to be considered the use of the RESET line to start
correctly the activity.
The preferable configuration is having an external supply for the buffer.
9.3. UART Behaviour
The UART ports have a different behaviour according to the module’s selected functional mode
(i.e. Power Saving).
Please refer to the SW User Guide to have a full overview of the Serial port signals behaviour in
the different selected conditions.