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lwIP PPP protocol

Associate II


How are you all doing?

To our application we integrated ST cellular stack to work with QUECTEL Modem M66 and all required features are working expected.

Now we decided to integrate lwIP stack from ST and use PPP protocol.

I made the initial settings like changing the SOCKET to use SOCKET_LWIP and started running the application.

At some point MCU sends AT command ATD *99***1# and CONNECT urc is recieved. Now the modem goes to data mode and starts sending steams of special characters as shown in image_1.jpg.

During this time, MCU calls ppp_write() and sends the configure -request as shown in image_2.jpg.

After this the MCU goes to endless wait state and stays in the lwip function sys_untimeout() untill some handler is matched (No idea what handler it needs).

meanwhile modem sends NO CARRIER and nothing works from there.

I am very new to this stack and I am really not sure if this is the expected behavior or something is wrong.

If anyone has faced this, Please give me some hints. Sadly, there is no example or documentation provided by ST :(




Hello @ANaga.2​ ,

Take a look at this reference :

It might be helpful.

BeST Regards,