SIM340 Hardware Design
Restrictions on autobauding operation
The serial port has to be operated at 8 data bits, no parity and 1 stop bit (factory setting).
The Unsolicited Result Codes like "RDY", "+CFUN: 1" and "+CPIN: READY” are not indicated
when you start up the ME while autobauding is enabled. This is due to the fact that the new baud
rate is not detected unless DTE and DCE are correctly synchronized as described above.
Note: You can use AT+IPR=x;&W to set a fixed baud rate and save the configuration to
non-volatile flash memory. After the configuration is saved as fixed baud rate, the Unsolicited
Result Codes like "RDY" should be received from the serial port all the time that the SIM340
was power on.
Debug port
Two lines on Debug port
Only contains Data lines /TXD and /RXD
Debug Port only used for debugging. It cannot be used for CSD call, FAX call. And the Debug
port can not use multiplexing function. It does not support autobauding function.
Debug port supports the communication rates as following:
9600, 19200, 38400, 57600, 115200bps
3.8.2 Software upgrade and software debug
The TXD
、
RXD
、
DBG_TXD
、
DBG_RXD and GND must be connected to the IO connector when
user need to upgrade software and debug software, the TXD
、
RXD should be used for software
upgrade and the DBG_TXD
、
DBG_RXD for software debugging. The PWRKEY pin is
recommended to connect to the IO connector. The user also can add a switch between the
PWRKEY and the GND. The PWRKEY should be connected to the GND when SIM340 is
upgrading software. Please refer to the following figures.
CUSTOMER(DTE)
TXD
RXD
GND
MODULE(DCE)
Serial port
TXD
RXD
GND
PWRKEY
SIM340_HD_V3.09
18.03.2009
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