M50 Hardware Design
M50_HD_V2.0
- 43 -
Used for AT command, GPRS data, etc. Multiplexing function is supported on the UART
Port. So far only the basic mode of multiplexing is available.
Support the communication baud rates as the following:
300, 600, 1200, 2400, 4800, 9600, 14400, 19200, 28800, 38400, 57600, 115200.
The default setting is autobauding mode. Support the following baud rates for Autobauding
function:
4800, 9600, 19200, 38400, 57600, 115200.
The module disables hardware flow control by default. AT command “AT+IFC=2,2” is used
to enable hardware flow control.
After setting a fixed baud rate or autobauding, please send “AT” string at that rate. The UART port
is ready when it responds “OK”.
Autobauding allows the module to detect the baud rate by receiving the string “AT” or “at” from
the host or PC automatically, which gives module flexibility without considering which baud rate
is used by the host controller. Autobauding is enabled by default. To take advantage of the
autobauding mode, special attention should be paid according to the following requirements:
Synchronization between DTE and DCE
:
When DCE (the module) powers on with the autobauding enabled, it is recommended to wait 2 to
3 seconds before sending the first AT character. After receiving the “OK” response, DTE and
DCE are correctly synchronized.
If the host controller needs URC in the mode of autobauding, it must be synchronized firstly.
Otherwise the URC will be discarded.
Restrictions on autobauding operation
:
The UART port has to be operated at 8 data bits, no parity and 1 stop bit (factory setting).
The “At” and “aT” commands cannot be used.
Only the strings “AT” or “at” can be detected (neither “At” nor “aT”).
The Unsolicited Result Codes like “RDY”, “+CFUN: 1” and “+CPIN: READY” will not be
indicated when the module is turned on with autobauding enabled and not be synchronized.
Any other Unsolicited Result Codes will be sent at the previous baud rate before the module
detects the new baud rate by receiving the first “AT” or “at” string. The DTE may receive
unknown characters after switching to new baud rate.
It is not recommended to switch to autobauding from a fixed baud rate.
If autobauding is active it is not recommended to switch to multiplex mode.
Note: To assure reliable communication and avoid any problems caused by undetermined baud
rate between DCE and DTE, it is strongly recommended to configure a fixed baud rate and save
it instead of using autobauding after start-up. For more details, please refer to the Section
“AT+IPR” in document [1].
Quecctel
Confidential
