I am working with FreeRTOS + LWIP on a project using PPPoS. I have been able
to successfully connect to the network and obtain an IP address after the
PPP negotiation using a modem that we have on our embedded device.
Once PPP negotiation completes, on our embedded device, I start my server
application to listen for incoming connection on a particular port. Every
time I attempt to connect to the server application from a client, I am
getting a "Connection reject".
I can successfully ping the device and get a ping response. The interesting
part is, whenever I set a breakpoint in the code where I expect data/traffic
to be taken out of the UART to be passed to the lwip stack for processing, I
do not hit this breakpoint.
I have placed a logic analyzer on the UART line and I do not see data when a
PPP session has been established. However, during the PPP negotiation
process, this path is the only way data gets to the LWIP stack and it is
My hypothesis is that the modem is receiving the traffic and
processing it internally instead of passing it through to the UART so that
the lwip stack can do the processing.
In view of the above, is there an option in LWIP that needs to be set for
PPP, so that the modem passes data transparently? Are there some
configuration for LWIP that I need to set?
On linux, I see these settings in the chat scripts. Are there some kind of
lwip equivalent that needs to be set?