TC35i AT Command Set
4.10 AT+IPR
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TC35i_ATC_V02.07 Page 102 of 439 1/30/04
Confidential / Released
4.10.1 Autobauding
To take advantage of autobaud mode specific attention must be paid to the following requirements:
• Synchronization between DTE and DCE
Ensure that DTE and DCE are correctly synchronized and the bit rate used by the DTE is detected by the
DCE (ME). To allow the bit rate to be synchronized simply use an "AT" or "at" string. This is necessary
- after you have activated autobauding
- when you start up the GSM engine while autobauding is enabled. It is recommended to wait 3 to 5 seconds
before sending the first AT character. Otherwise undefined characters might be returned.
If you want to use autobauding and autoanswer at the same time, you can easily enable the DTE-DCE syn-
chronization, when you activate autobauding first and then configure the autoanswer mode (
ATS0 ¹ 0).
• Restrictions on autobauding operation
- The serial interface shall be used with 8 data bits, no parity and 1 stop bit (factory setting), e.g. 2 stop bits
are not supported for autobaud mode.
-
A/ cannot be used.
- Only the strings "AT" or "at" can be detected (neither "At" nor "aT").
- URCs that may be issued before the ME detects a new bit rate (by receiving the first AT character) will be
sent at the previously detected bit rate or, after ME restart, at 57600 bps.
- It is not recommended to switch to autobauding from a bit rate that cannot be detected by the the autobaud
mechanism (e.g. 300 bps). Responses to
AT+IPR=0 and any commands on the same line might be cor-
rupted.
- If entering several AT commands on the same line, consider the requirements described above.
- When autobauding is switched on:
+ only data length, parity and baud rate are automatically detected
+ if using 1 stop bit,
AT+ICF=1 should not be used, because it uses 2 stop bits
+ if using 2 stop bits, no combination of
AT+ICF should be used, which uses 1 stop bit
- Terminal version of TC35i shall not use autobauding with baudrates above 115200bps.
• Autobauding and bit rate after restart
The most recently detected bit rate is stored when the ME is powered down (with
AT^SMSO). Therefore, each
time the module is restarted the correct bit rate must be found as described above. Unless the bit rate is deter-
mined, the following constraints apply:
- An incoming CSD call cannot be accepted. This must be taken into account when autobauding and
autoanswer mode (
ATS0 ¹ 0) are enabled at the same time, escpecially if SIM PIN 1 authentication is done
automatically and the setting
ATS0 ¹ 0 is stored to the user profile with AT&W.
- Until the bit rate is found, URCs generated after restart will be output at 57600 bps. This applies only to
user defined URCs, such as "+CREG", "CCWA", "^SCKS" etc. The URCs "^SYSSTART", "^SYSSTART
ALARM MODE" and "^SYSSTART CHARGE-ONLY MODE" will not be indicated when autobauding is
enabled.
Note: To avoid any problems caused by undetermined bit rates in the direction from DCE to DTE we strongly
recommend to configure a fixed bit rate rather than autobauding.
• Autobauding and multiplex mode
While TC35i is using autobauding its serial interface can't be switched to multiplex mode via
AT+CMUX. If mul-
tiplex mode is already enabled neither autobauding nor any fixed baudrate can be selected with
AT+IPR.
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