User guide

M80 EVB User Guide
M80_EVB_User_Guide_V1.2 - 25 -
Figure 23: Antenna interface
3.6. Communication
M80 provides multi type communication ports, such as main UART, Auxiliary UART, Debug
UART and USB port.
3.6.1. Main UART
When using main UART port communicates data between PC and the module, a RS_232 level
shifter must be inserted between them, since this UART port do not support the RS_232 level,
while supports the CMOS level only. The following picture is the reference design of RS-232
level shifter. The main UART can be used for AT command, GPRS data, CSD FAX, etc.
Multiplexing function is supported on the main UART Port as well. For the design circuit of main
Port, please refer to document [2]. For more details about communication with UART, please
refer to chapter 5.4.1.
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