User's Manual

GSM/GPRS/GNSS Module Series
MC60 Hardware Design
MC60_Hardware_Design Confidential / Released 55 / 99
Figure 27: Auxiliary and GNSS UART Port Connection in Stand-alone Solution
3.7.4. UART Application
A reference design of 3.3V level match is shown as below. If the host is a 3V system, please change the
5.6K resistors to 10K ones.
Figure 28: Level Match Design for 3.3V System
It is highly recommended to add the resistor divider circuit on the UART signal lines when the host’s level
is 3V or 3.3V. For a higher voltage level system, a level shifter IC could be used between the host and the
module. For more details about UART circuit design, please refer to document [13].
The following figure shows a sketch map between the module and the standard RS-232 interface. As the
electrical level of module is 2.8V, a RS-232 level shifter must be used. Note that you should assure the
I/O voltage of level shifter which connects to module is 2.8V.
NOTE