Dear,
I was looking at the data being sent/received over uart when ppp is being negotiated. I was surprised to see that the received byte stream is always wrapped in 0x7e bytes (leading + trailing).
But for some reason this is not the case for the bytes lwip sends (/provides to my sio_write function). Even stronger, sometimes it does start with a leading 0x7e, sometimes it doesn't.
On the wiki I read:
"PPP packets all start and end with 0x7E. If you don't see these, something is wrong with your low level driver"
When I look at fsm.c where the PPP header is created, I don't see 0x7e being added as part of the opening header.
pppos works, lwip works, I can open sockets, download from FTP, etc. So what's the deal with this? Should I investigate further and is there a bug sitting in my code? Or is this "perfectly normal" behavior and is the wiki wrong?
I added the logic analyzer export to this email.
Hopefully someone can shed some light on this.
best regards, bas
export.csv