SARA-R42 - Application note
UBX-20050829 - R02 Local connectivity Page 16 of 58
C1-Public
☞ It is not possible to have parallel activities on AT terminals when the multiplexer is activated
through the +CMUX AT command. The only allowed parallel activity is present when it is defined a
system architecture with a PPP dial-up on one port and AT commands on the other port.
☞ URCs are sent to all available AT interfaces when the multiplexer functionality is applied.
☞ The multiplexer protocol is not supported in the configurations having the AUX UART interface
enabled (for example, +USIO: 1, +USIO: 4).
5.4 Point-to-point protocol (PPP)
Data (PSD) calls are possible over both primary UART and auxiliary UART interfaces.
☞ If the double UART configuration is used, the full V24 modem lines are not supported. In this
configuration, entering in OLCM or disconnecting the PPP connection via DTR line de-assertion is
not possible.
☞ Issue the AT+CVHU=0 command to make ATH over Online Command Mode (OLCM) work,
according to 3GPP requirements. If the module has a DUN/PPP activated and is in OLCM, the
command deactivates the PPP and the associated PDP context (if possible).
Further information about PPP dial-up establishment can be found in the Internet applications
development guide application note [5] and in the EVK-R4 user guide [11].
5.5 Generic guidelines
To properly configure local connectivity, the following steps shall be considered:
1. Set the required connectivity variant at first usage, via the +USIO AT command.
2. Configure the GPIOs based on the set variant (especially in reference to the RI line), via the
+UGPIOC AT command.
3. Configure the power saving control mode based on the set variant, via the +UPSV AT command.