User guide

M80 EVB User Guide
M80_EVB_User_Guide_V1.2 - 27 -
7
RTS
I
Request to send
8
CTS
O
Clear to send
9
RI
O
Ring indicator
Note: The above pins are RS232 voltage level.
The TTL level of UART signal can be test through test points below. Customer can use these test
points to verify the design between customer device and the module.
Figure 26: Test points of main port
The main port can be used for upgrading software. The PWRKEY pin must be pulled down before
the software upgrade. For more details about downloading software with UART, please refer to
chapter 5.5.1.
3.6.2. Auxiliary UART and Debug UART
When Auxiliary UART port and Debug Port are used to communicate data between PC and the
module, a RS_232 level shifter must be inserted between them. The reference design is same as
the main port. Auxiliary UART port is used for AT command only since it does not support GPRS
data, CSD FAX, and Multiplexing function, etc. Debug Port is only used for software debugging
and its baud rate must be configured as 460800bps. For the circuit design of Auxiliary UART port
and Debug Port, please refer to document [3] and document [5].
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