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Re: [lwip-users] lwip-users Digest, Vol 214, Issue 8
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Re: [lwip-users] lwip-users Digest, Vol 214, Issue 8 |
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Tue, 8 Jun 2021 08:40:21 +0200 |
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Thanks,
Simon
Am 07.06.2021 um 23:23 schrieb Bas Prins:
> Dear Rüdiger,
>
> I think you already perfectly answered my question(s). I'm really
> grateful for that. This wasn't blocking me from proceeding, but it's
> really annoying for me to not understand half of what I am doing. You
> helped me to understand 51% of what I am doing which is good enough for
> now not to sink and drown ;-).
>
> I will google for the ISO 3309 spec and search for the information you
> mentioned. I noticed that wikipedia reveals interesting things if I type
> in the correct keywords :)
>
> Thanks again for clarifying some bits and pieces for me!!
>
> Best regards, bas
>
> Op ma 7 jun. 2021 om 23:13 schreef <lwip-users-request@nongnu.org
> <mailto:lwip-users-request@nongnu.org>>:
>
> Send lwip-users mailing list submissions to
> lwip-users@nongnu.org <mailto:lwip-users@nongnu.org>
>
> To subscribe or unsubscribe via the World Wide Web, visit
> https://lists.nongnu.org/mailman/listinfo/lwip-users
> <https://lists.nongnu.org/mailman/listinfo/lwip-users>
> or, via email, send a message with subject or body 'help' to
> lwip-users-request@nongnu.org
> <mailto:lwip-users-request@nongnu.org>
>
> You can reach the person managing the list at
> lwip-users-owner@nongnu.org <mailto:lwip-users-owner@nongnu.org>
>
> When replying, please edit your Subject line so it is more specific
> than "Re: Contents of lwip-users digest..."
>
>
> Today's Topics:
>
> 1. Re: pppos sent packets optionally start with 0x7e, why?
> (Rüdiger Asche)
>
>
> ----------------------------------------------------------------------
>
> Message: 1
> Date: Mon, 7 Jun 2021 23:12:08 +0200
> From: Rüdiger Asche <ruediger_asche@t-online.de
> <mailto:ruediger_asche@t-online.de>>
> To: "Mailing list for lwIP users" <lwip-users@nongnu.org
> <mailto:lwip-users@nongnu.org>>
> Subject: Re: [lwip-users] pppos sent packets optionally start with
> 0x7e, why?
> Message-ID: <BA745CE95ED940CCB793BEA922328F28@RACTOMCOVE>
> Content-Type: text/plain; charset="utf-8"
>
> Hi Bas,
>
> if you have access to the ISO 3309 spec which defines HDLC, look for
> the statement
>
> "A single flag may be used as both the closing flag for one frame
> and the opening flag for the next frame."
>
> in chapter 4.1.
>
> I suspect that this explains the observation you make. The closing
> frame character of the last frame is recycled as the frame start
> character for the next frame, remembered by the peer.
>
> The easiest way to verify this is to look at the HDLC frame parser
> and -generator in lwip. I can't tell you where to look since it's
> been decades I worked with PPP (never under lwip), but it shouldn't
> be too hard to find in the code base.
>
> Thanks Rüdiger
> ----- Original Message -----
> From: Bas Prins
> To: lwip-users@nongnu.org <mailto:lwip-users@nongnu.org>
> Sent: Monday, June 07, 2021 10:43 PM
> Subject: Re: [lwip-users] lwip-users Digest, Vol 214, Issue 6
>
>
> Dear Rüdiger ,
>
>
> Thanks for the detailed answer and the link (haven't read that,
> learned a lot from reading).
>
>
> When I read this, I understand what you mentioned, and that the
> sender is allowed to omit the TRAILING 0x7e byte. But in my case,
> it's not really the trailing byte (or I am still missing the obvious
> here... :))
>
>
> It might be hard to digest from the CSV data, but this is what I
> can see in my logic analyzer:
>
>
> STM starts (after modem reaches data mode):
> 0x7e ..... 0x7e - send first packet, wrapped in 0x7e bytes.
>
>
> After roughly 500us the peer replies:
> 0x7e ...... 0x7e - again a ppp packet wrapped in 0x7e bytes
>
>
> STM responds and sends a second packet:
> 0xFF .. 0x7e : This is what struck me. Shouldn't this BEGIN with a
> 0x7e?
>
>
>
> It already sent it's "omitable leading 0x7e byte" to enclose the
> first packet. So it should start with a 0x7e byte now, right? Or
> does the peer accept the trailing 0x7e byte of the FIRST sent packet
> as leading 0x7e for the second packet??
>
>
> I interpreted this part as the FIRST 0x7e byte of the second sent
> PPP packet is omitted.
>
>
> What am I still missing?
>
>
> Best regards, bas
>
>
>
>
>
>
>
>
>
>
> Op ma 7 jun. 2021 om 21:28 schreef <lwip-users-request@nongnu.org
> <mailto:lwip-users-request@nongnu.org>>:
>
> Send lwip-users mailing list submissions to
> lwip-users@nongnu.org <mailto:lwip-users@nongnu.org>
>
> To subscribe or unsubscribe via the World Wide Web, visit
> https://lists.nongnu.org/mailman/listinfo/lwip-users
> <https://lists.nongnu.org/mailman/listinfo/lwip-users>
> or, via email, send a message with subject or body 'help' to
> lwip-users-request@nongnu.org
> <mailto:lwip-users-request@nongnu.org>
>
> You can reach the person managing the list at
> lwip-users-owner@nongnu.org
> <mailto:lwip-users-owner@nongnu.org>
>
> When replying, please edit your Subject line so it is more specific
> than "Re: Contents of lwip-users digest..."
>
>
> Today's Topics:
>
> 1. Re: pppos sent packets optionally start with 0x7e, why?
> (Rüdiger Asche)
>
>
>
> ----------------------------------------------------------------------
>
> Message: 1
> Date: Mon, 7 Jun 2021 21:27:33 +0200
> From: Rüdiger Asche <ruediger_asche@t-online.de
> <mailto:ruediger_asche@t-online.de>>
> To: "Mailing list for lwIP users" <lwip-users@nongnu.org
> <mailto:lwip-users@nongnu.org>>
> Subject: Re: [lwip-users] pppos sent packets optionally start with
> 0x7e, why?
> Message-ID: <F01ACCC173FC4DFB8EC67D8A6C1E9859@RACTOMCOVE>
> Content-Type: text/plain; charset="utf-8"
>
> Hi there Bas,
>
> have you looked at the HDLC encoding rules? In
> https://en.wikipedia.org/wiki/Point-to-Point_Protocol
> <https://en.wikipedia.org/wiki/Point-to-Point_Protocol> , about half
> way down, it reads
>
> "0x7E, omitted for successive PPP packets"
>
> for the frame END character. So to me it looks as if it's not
> the leading frame character but the trailing one that's missing,
> which is specification compliant. Makes sense too to omit it because
> the inner structure of a frame past the sync char allows for full
> parsing of a well formed packet (of course taking into account the
> negotiated PFC and AFC compression restrictions). Note that the
> first LCP packet (decoded here) is still fully framed:
>
> ff03 c021 1 1 => LCP conf request
> 0 14 => length
> 2 6 0 0 0 0 =>
> 5 6 40 b1 9c e9 => magic number
> 7 2 => Protocol field compression
> 8 2 => AFC compression
> 38 b7 => => frame checksum
>
>
> Afterwards, both sides have all the information they need to
> parse a peer's frame without a trailing framing character.
>
>
>
> ----- Original Message -----
> From: Bas Prins
> To: lwip-users@nongnu.org <mailto:lwip-users@nongnu.org>
> Sent: Monday, June 07, 2021 7:00 PM
> Subject: Re: [lwip-users] pppos sent packets optionally start
> with 0x7e, why?
>
>
> I think the CSV attachment was dropped by server. Trying to
> add the CSV as plain text below.
>
>
> Async Serial == RX
> Async Serial [1] == TX
>
>
> Leading 0x7E byte is not provided by LWIP in when it calls
> sio_write.
>
>
>
>
>
>
> name type start_time duration data
>
> Async Serial [1] data 5.80629 8.25E-05 0x41
>
> Async Serial [1] data 5.806378 8.25E-05 0x54
>
> Async Serial [1] data 5.806466 8.25E-05 0x0D
>
> Async Serial [1] data 6.936377 8.25E-05 0x2B
>
> Async Serial [1] data 6.946236 8.25E-05 0x2B
>
> Async Serial [1] data 6.95636 8.25E-05 0x2B
>
> Async Serial data 7.865252 8.25E-05 0x0D
>
> Async Serial data 7.865339 8.25E-05 0x0A
>
> Async Serial data 7.865426 8.25E-05 0x4F
>
> Async Serial data 7.865513 8.25E-05 0x4B
>
> Async Serial data 7.865599 8.25E-05 0x0D
>
> Async Serial data 7.865686 8.25E-05 0x0A
>
> Async Serial [1] data 7.869666 8.25E-05 0x41
>
> Async Serial [1] data 7.869754 8.25E-05 0x54
>
> Async Serial [1] data 7.869842 8.25E-05 0x4F
>
> Async Serial [1] data 7.86993 8.25E-05 0x0D
>
> Async Serial data 7.871056 8.25E-05 0x0D
>
> Async Serial data 7.871143 8.25E-05 0x0A
>
> Async Serial data 7.87123 8.25E-05 0x43
>
> Async Serial data 7.871317 8.25E-05 0x4F
>
> Async Serial data 7.871403 8.25E-05 0x4E
>
> Async Serial data 7.87149 8.25E-05 0x4E
>
> Async Serial data 7.871577 8.25E-05 0x45
>
> Async Serial data 7.871664 8.25E-05 0x43
>
> Async Serial data 7.871751 8.25E-05 0x54
>
> Async Serial data 7.871837 8.25E-05 0x20
>
> Async Serial data 7.871924 8.25E-05 0x31
>
> Async Serial data 7.872011 8.25E-05 0x31
>
> Async Serial data 7.872098 8.25E-05 0x35
>
> Async Serial data 7.872185 8.25E-05 0x32
>
> Async Serial data 7.872271 8.25E-05 0x30
>
> Async Serial data 7.872358 8.25E-05 0x30
>
> Async Serial data 7.872445 8.25E-05 0x0D
>
> Async Serial data 7.872532 8.25E-05 0x0A up until here
> is AT commands to put modem in ppp. That succeeded here.
> Async Serial [1] data 7.895673 8.25E-05 0x7E First
> packet sent over uart from STM
> Async Serial [1] data 7.895761 8.25E-05 0xFF
>
> Async Serial [1] data 7.895849 8.25E-05 0x7D
>
> Async Serial [1] data 7.895937 8.25E-05 0x23
>
> Async Serial [1] data 7.896025 8.25E-05 0xC0
>
> Async Serial [1] data 7.896113 8.25E-05 0x21
>
> Async Serial [1] data 7.896201 8.25E-05 0x7D
>
> Async Serial [1] data 7.896289 8.25E-05 0x21
>
> Async Serial [1] data 7.896377 8.25E-05 0x7D
>
> Async Serial [1] data 7.896465 8.25E-05 0x21
>
> Async Serial [1] data 7.896553 8.25E-05 0x7D
>
> Async Serial [1] data 7.896641 8.25E-05 0x20
>
> Async Serial [1] data 7.896729 8.25E-05 0x7D
>
> Async Serial [1] data 7.896817 8.25E-05 0x34
>
> Async Serial [1] data 7.896905 8.25E-05 0x7D
>
> Async Serial [1] data 7.896993 8.25E-05 0x22
>
> Async Serial [1] data 7.897081 8.25E-05 0x7D
>
> Async Serial [1] data 7.897169 8.25E-05 0x26
>
> Async Serial [1] data 7.897257 8.25E-05 0x7D
>
> Async Serial [1] data 7.897345 8.25E-05 0x20
>
> Async Serial [1] data 7.897433 8.25E-05 0x7D
>
> Async Serial [1] data 7.897521 8.25E-05 0x20
>
> Async Serial [1] data 7.897609 8.25E-05 0x7D
>
> Async Serial [1] data 7.897697 8.25E-05 0x20
>
> Async Serial [1] data 7.897785 8.25E-05 0x7D
>
> Async Serial [1] data 7.897872 8.25E-05 0x20
>
> Async Serial [1] data 7.89796 8.25E-05 0x7D
>
> Async Serial [1] data 7.898048 8.25E-05 0x25
>
> Async Serial [1] data 7.898136 8.25E-05 0x7D
>
> Async Serial [1] data 7.898224 8.25E-05 0x26
>
> Async Serial [1] data 7.898312 8.25E-05 0x40
>
> Async Serial [1] data 7.8984 8.25E-05 0xB1
>
> Async Serial [1] data 7.898488 8.25E-05 0x9C
>
> Async Serial [1] data 7.898576 8.25E-05 0xE9
>
> Async Serial [1] data 7.898664 8.25E-05 0x7D
>
> Async Serial [1] data 7.898752 8.25E-05 0x27
>
> Async Serial [1] data 7.89884 8.25E-05 0x7D
>
> Async Serial [1] data 7.898928 8.25E-05 0x22
>
> Async Serial [1] data 7.899017 8.25E-05 0x7D
>
> Async Serial [1] data 7.899105 8.25E-05 0x28
>
> Async Serial [1] data 7.899193 8.25E-05 0x7D
>
> Async Serial [1] data 7.899281 8.25E-05 0x22
>
> Async Serial [1] data 7.899369 8.25E-05 0x38
>
> Async Serial [1] data 7.899457 8.25E-05 0xB7
>
> Async Serial [1] data 7.899545 8.25E-05 0x7E end first
> packet
> Async Serial data 7.900403 8.25E-05 0x7E first received
> ppp packet on rx line
> Async Serial data 7.90049 8.25E-05 0xFF
>
> Async Serial data 7.900576 8.25E-05 0x7D
>
> Async Serial data 7.900663 8.25E-05 0x23
>
> Async Serial data 7.90075 8.25E-05 0xC0
>
> Async Serial data 7.900837 8.25E-05 0x21
>
> Async Serial data 7.900924 8.25E-05 0x7D
>
> Async Serial data 7.90101 8.25E-05 0x21
>
> Async Serial data 7.901097 8.25E-05 0xE5
>
> Async Serial data 7.901184 8.25E-05 0x7D
>
> Async Serial data 7.901271 8.25E-05 0x20
>
> Async Serial data 7.901358 8.25E-05 0x7D
>
> Async Serial data 7.901444 8.25E-05 0x39
>
> Async Serial data 7.901531 8.25E-05 0x7D
>
> Async Serial data 7.901618 8.25E-05 0x22
>
> Async Serial data 7.901705 8.25E-05 0x7D
>
> Async Serial data 7.901792 8.25E-05 0x26
>
> Async Serial data 7.901878 8.25E-05 0x7D
>
> Async Serial data 7.901965 8.25E-05 0x20
>
> Async Serial data 7.902052 8.25E-05 0x7D
>
> Async Serial data 7.902139 8.25E-05 0x20
>
> Async Serial data 7.902226 8.25E-05 0x7D
>
> Async Serial data 7.902312 8.25E-05 0x20
>
> Async Serial data 7.902399 8.25E-05 0x7D
>
> Async Serial data 7.902486 8.25E-05 0x20
>
> Async Serial data 7.902573 8.25E-05 0x7D
>
> Async Serial data 7.90266 8.25E-05 0x23
>
> Async Serial data 7.902746 8.25E-05 0x7D
>
> Async Serial data 7.902833 8.25E-05 0x25
>
> Async Serial data 7.90292 8.25E-05 0xC2
>
> Async Serial data 7.903007 8.25E-05 0x23
>
> Async Serial data 7.903094 8.25E-05 0x7D
>
> Async Serial data 7.90318 8.25E-05 0x25
>
> Async Serial data 7.903267 8.25E-05 0x7D
>
> Async Serial data 7.903354 8.25E-05 0x25
>
> Async Serial data 7.903441 8.25E-05 0x7D
>
> Async Serial data 7.903528 8.25E-05 0x26
>
> Async Serial data 7.903614 8.25E-05 0x26
>
> Async Serial data 7.903701 8.25E-05 0xA6
>
> Async Serial data 7.903788 8.25E-05 0x32
>
> Async Serial data 7.903875 8.25E-05 0x2F
>
> Async Serial data 7.903962 8.25E-05 0x7D
>
> Async Serial data 7.904049 8.25E-05 0x27
>
> Async Serial data 7.904135 8.25E-05 0x7D
>
> Async Serial data 7.904222 8.25E-05 0x22
>
> Async Serial data 7.904309 8.25E-05 0x7D
>
> Async Serial data 7.904396 8.25E-05 0x28
>
> Async Serial data 7.904483 8.25E-05 0x7D
>
> Async Serial data 7.904569 8.25E-05 0x22
>
> Async Serial data 7.904656 8.25E-05 0xD7
>
> Async Serial data 7.904743 8.25E-05 0x73
>
> Async Serial data 7.90483 8.25E-05 0x7E
>
> Async Serial data 7.904917 8.25E-05 0x7E
>
> Async Serial data 7.905003 8.25E-05 0xFF
>
> Async Serial data 7.90509 8.25E-05 0x7D
>
> Async Serial data 7.905177 8.25E-05 0x23
>
> Async Serial data 7.905264 8.25E-05 0xC0
>
> Async Serial data 7.905351 8.25E-05 0x21
>
> Async Serial data 7.905437 8.25E-05 0x7D
>
> Async Serial data 7.905524 8.25E-05 0x22
>
> Async Serial data 7.905611 8.25E-05 0x7D
>
> Async Serial data 7.905698 8.25E-05 0x21
>
> Async Serial data 7.905785 8.25E-05 0x7D
>
> Async Serial data 7.905871 8.25E-05 0x20
>
> Async Serial data 7.905958 8.25E-05 0x7D
>
> Async Serial data 7.906045 8.25E-05 0x34
>
> Async Serial data 7.906132 8.25E-05 0x7D
>
> Async Serial data 7.906219 8.25E-05 0x22
>
> Async Serial data 7.906305 8.25E-05 0x7D
>
> Async Serial data 7.906392 8.25E-05 0x26
>
> Async Serial data 7.906479 8.25E-05 0x7D
>
> Async Serial data 7.906566 8.25E-05 0x20
>
> Async Serial data 7.906653 8.25E-05 0x7D
>
> Async Serial data 7.906739 8.25E-05 0x20
>
> Async Serial data 7.906826 8.25E-05 0x7D
>
> Async Serial data 7.906913 8.25E-05 0x20
>
> Async Serial data 7.907 8.25E-05 0x7D
>
> Async Serial data 7.907087 8.25E-05 0x20
>
> Async Serial data 7.907173 8.25E-05 0x7D
>
> Async Serial data 7.90726 8.25E-05 0x25
>
> Async Serial data 7.907347 8.25E-05 0x7D
>
> Async Serial data 7.907434 8.25E-05 0x26
>
> Async Serial data 7.907521 8.25E-05 0x40
>
> Async Serial data 7.907608 8.25E-05 0xB1
>
> Async Serial data 7.907694 8.25E-05 0x9C
>
> Async Serial data 7.907781 8.25E-05 0xE9
>
> Async Serial data 7.907868 8.25E-05 0x7D
>
> Async Serial data 7.907955 8.25E-05 0x27
>
> Async Serial data 7.908042 8.25E-05 0x7D
>
> Async Serial data 7.908128 8.25E-05 0x22
>
> Async Serial data 7.908215 8.25E-05 0x7D
>
> Async Serial data 7.908302 8.25E-05 0x28
>
> Async Serial data 7.908389 8.25E-05 0x7D
>
> Async Serial data 7.908476 8.25E-05 0x22
>
> Async Serial data 7.908562 8.25E-05 0xD3
>
> Async Serial data 7.908649 8.25E-05 0xDE
>
> Async Serial data 7.908736 8.25E-05 0x7E end first
> received ppp packet
> Async Serial [1] data 7.913322 8.25E-05 0xFF second ppp
> packet sent by STM, why is the 0x7E byte ommitted? I also attached
> debugger to get data bytes provided by LWIP, first byte is -0xFF
> Async Serial [1] data 7.91341 8.25E-05 0x7D
>
> Async Serial [1] data 7.913498 8.25E-05 0x23
>
> Async Serial [1] data 7.913586 8.25E-05 0xC0
>
> Async Serial [1] data 7.913674 8.25E-05 0x21
>
> Async Serial [1] data 7.913762 8.25E-05 0x7D
>
> Async Serial [1] data 7.91385 8.25E-05 0x24
>
> Async Serial [1] data 7.913938 8.25E-05 0xE5
>
> Async Serial [1] data 7.914026 8.25E-05 0x7D
>
> Async Serial [1] data 7.914114 8.25E-05 0x20
>
> Async Serial [1] data 7.914202 8.25E-05 0x7D
>
> Async Serial [1] data 7.91429 8.25E-05 0x29
>
> Async Serial [1] data 7.914378 8.25E-05 0x7D
>
> Async Serial [1] data 7.914466 8.25E-05 0x23
>
> Async Serial [1] data 7.914554 8.25E-05 0x7D
>
> Async Serial [1] data 7.914642 8.25E-05 0x25
>
> Async Serial [1] data 7.91473 8.25E-05 0xC2
>
> Async Serial [1] data 7.914818 8.25E-05 0x23
>
> Async Serial [1] data 7.914906 8.25E-05 0x7D
>
> Async Serial [1] data 7.914994 8.25E-05 0x25
>
> Async Serial [1] data 7.915082 8.25E-05 0x7A
>
> Async Serial [1] data 7.91517 8.25E-05 0xEF
>
> Async Serial [1] data 7.915258 8.25E-05 0x7E
>
> Async Serial data 7.915929 8.25E-05 0x7E
>
> Async Serial data 7.916016 8.25E-05 0xFF
>
> Async Serial data 7.916102 8.25E-05 0x7D
>
> Async Serial data 7.916189 8.25E-05 0x23
>
> Async Serial data 7.916276 8.25E-05 0xC0
>
> Async Serial data 7.916363 8.25E-05 0x21
>
> Async Serial data 7.91645 8.25E-05 0x7D
>
> Async Serial data 7.916536 8.25E-05 0x21
>
> Async Serial data 7.916623 8.25E-05 0xE6
>
> Async Serial data 7.91671 8.25E-05 0x7D
>
> Async Serial data 7.916797 8.25E-05 0x20
>
> Async Serial data 7.916884 8.25E-05 0x7D
>
> Async Serial data 7.916971 8.25E-05 0x34
>
> Async Serial data 7.917057 8.25E-05 0x7D
>
> Async Serial data 7.917144 8.25E-05 0x22
>
> Async Serial data 7.917231 8.25E-05 0x7D
>
> Async Serial data 7.917318 8.25E-05 0x26
>
> Async Serial data 7.917405 8.25E-05 0x7D
>
> Async Serial data 7.917491 8.25E-05 0x20
>
> Async Serial data 7.917578 8.25E-05 0x7D
>
> Async Serial data 7.917665 8.25E-05 0x20
>
> Async Serial data 7.917752 8.25E-05 0x7D
>
> Async Serial data 7.917839 8.25E-05 0x20
>
> Async Serial data 7.917925 8.25E-05 0x7D
>
> Async Serial data 7.918012 8.25E-05 0x20
>
> Async Serial data 7.918099 8.25E-05 0x7D
>
> Async Serial data 7.918186 8.25E-05 0x25
>
> Async Serial data 7.918273 8.25E-05 0x7D
>
> Async Serial data 7.918359 8.25E-05 0x26
>
> Async Serial data 7.918446 8.25E-05 0x26
>
> Async Serial data 7.918533 8.25E-05 0xA6
>
> Async Serial data 7.91862 8.25E-05 0x32
>
> Async Serial data 7.918707 8.25E-05 0x2F
>
> Async Serial data 7.918793 8.25E-05 0x7D
>
> Async Serial data 7.91888 8.25E-05 0x27
>
> Async Serial data 7.918967 8.25E-05 0x7D
>
> Async Serial data 7.919054 8.25E-05 0x22
>
> Async Serial data 7.919141 8.25E-05 0x7D
>
> Async Serial data 7.919227 8.25E-05 0x28
>
> Async Serial data 7.919314 8.25E-05 0x7D
>
> Async Serial data 7.919401 8.25E-05 0x22
>
> Async Serial data 7.919488 8.25E-05 0x46
>
> Async Serial data 7.919575 8.25E-05 0xDA
>
> Async Serial data 7.919661 8.25E-05 0x7E
>
> Async Serial [1] data 7.9253 8.25E-05 0xFF
>
> Async Serial [1] data 7.925388 8.25E-05 0x7D
>
> Async Serial [1] data 7.925476 8.25E-05 0x23
>
> Async Serial [1] data 7.925564 8.25E-05 0xC0
>
> Async Serial [1] data 7.925652 8.25E-05 0x21
>
> Async Serial [1] data 7.92574 8.25E-05 0x7D
>
> Async Serial [1] data 7.925828 8.25E-05 0x22
>
> Async Serial [1] data 7.925916 8.25E-05 0xE6
>
> Async Serial [1] data 7.926004 8.25E-05 0x7D
>
> Async Serial [1] data 7.926092 8.25E-05 0x20
>
> Async Serial [1] data 7.92618 8.25E-05 0x7D
>
> Async Serial [1] data 7.926268 8.25E-05 0x34
>
> Async Serial [1] data 7.926356 8.25E-05 0x7D
>
> Async Serial [1] data 7.926444 8.25E-05 0x22
>
> Async Serial [1] data 7.926532 8.25E-05 0x7D
>
> Async Serial [1] data 7.92662 8.25E-05 0x26
>
> Async Serial [1] data 7.926708 8.25E-05 0x7D
>
> Async Serial [1] data 7.926796 8.25E-05 0x20
>
> Async Serial [1] data 7.926884 8.25E-05 0x7D
>
> Async Serial [1] data 7.926972 8.25E-05 0x20
>
> Async Serial [1] data 7.92706 8.25E-05 0x7D
>
> Async Serial [1] data 7.927149 8.25E-05 0x20
>
> Async Serial [1] data 7.927237 8.25E-05 0x7D
>
> Async Serial [1] data 7.927325 8.25E-05 0x20
>
> Async Serial [1] data 7.927413 8.25E-05 0x7D
>
> Async Serial [1] data 7.927501 8.25E-05 0x25
>
> Async Serial [1] data 7.927589 8.25E-05 0x7D
>
> Async Serial [1] data 7.927677 8.25E-05 0x26
>
> Async Serial [1] data 7.927765 8.25E-05 0x26
>
> Async Serial [1] data 7.927853 8.25E-05 0xA6
>
> Async Serial [1] data 7.927941 8.25E-05 0x32
>
> Async Serial [1] data 7.928029 8.25E-05 0x2F
>
> Async Serial [1] data 7.928117 8.25E-05 0x7D
>
> Async Serial [1] data 7.928205 8.25E-05 0x27
>
> Async Serial [1] data 7.928293 8.25E-05 0x7D
>
> Async Serial [1] data 7.928381 8.25E-05 0x22
>
> Async Serial [1] data 7.928469 8.25E-05 0x7D
>
> Async Serial [1] data 7.928557 8.25E-05 0x28
>
> Async Serial [1] data 7.928645 8.25E-05 0x7D
>
> Async Serial [1] data 7.928733 8.25E-05 0x22
>
> Async Serial [1] data 7.928821 8.25E-05 0xAD
>
> Async Serial [1] data 7.928909 8.25E-05 0xB3
>
> Async Serial [1] data 7.928997 8.25E-05 0x7E
>
> Async Serial [1] data 7.929411 8.25E-05 0xFF
>
> Async Serial [1] data 7.929499 8.25E-05 0x03
>
> Async Serial [1] data 7.929587 8.25E-05 0x80
>
> Async Serial data 7.929658 8.25E-05 0x7E
>
> Async Serial [1] data 7.929675 8.25E-05 0x21
>
> Async Serial data 7.929744 8.25E-05 0xFF
>
> Async Serial [1] data 7.929763 8.25E-05 0x01
>
> Async Serial data 7.929831 8.25E-05 0x7D
>
> Async Serial [1] data 7.929851 8.25E-05 0x01
>
> Async Serial data 7.929918 8.25E-05 0x23
>
> Async Serial [1] data 7.929939 8.25E-05 0x00
>
> Async Serial data 7.930005 8.25E-05 0xC0
>
> Async Serial [1] data 7.930027 8.25E-05 0x0A
>
> Async Serial data 7.930092 8.25E-05 0x21
>
> Async Serial [1] data 7.930115 8.25E-05 0x03
>
> Async Serial data 7.930178 8.25E-05 0x7D
>
> Async Serial [1] data 7.930203 8.25E-05 0x06
>
> Async Serial data 7.930265 8.25E-05 0x2B
>
> Async Serial [1] data 7.930291 8.25E-05 0x00
>
> Async Serial data 7.930352 8.25E-05 0xE7
>
> Async Serial [1] data 7.930379 8.25E-05 0x00
>
> Async Serial data 7.930439 8.25E-05 0x7D
>
> Async Serial [1] data 7.930467 8.25E-05 0x00
>
> Async Serial data 7.930526 8.25E-05 0x20
>
> Async Serial [1] data 7.930555 8.25E-05 0x00
>
> Async Serial data 7.930612 8.25E-05 0x7D
>
> Async Serial data 7.930699 8.25E-05 0x28
>
> Async Serial data 7.930786 8.25E-05 0x26
>
> Async Serial data 7.930873 8.25E-05 0xA6
>
> Async Serial data 7.93096 8.25E-05 0x32
>
> Async Serial data 7.931046 8.25E-05 0x2F
>
> Async Serial data 7.931133 8.25E-05 0x74
>
> Async Serial data 7.93122 8.25E-05 0xC1
>
> Async Serial data 7.931307 8.25E-05 0x7E
>
> Async Serial [1] data 7.931541 8.25E-05 0x13
>
> Async Serial [1] data 7.931629 8.25E-05 0x28
>
> Async Serial [1] data 7.931717 8.25E-05 0x7E
>
> Async Serial data 7.93236 8.25E-05 0x7E
>
> Async Serial data 7.932447 8.25E-05 0x80
>
> Async Serial data 7.932534 8.25E-05 0x21
>
> Async Serial data 7.93262 8.25E-05 0x01
>
> Async Serial data 7.932707 8.25E-05 0xFD
>
> Async Serial data 7.932794 8.25E-05 0x00
>
> Async Serial data 7.932881 8.25E-05 0x04
>
> Async Serial data 7.932968 8.25E-05 0x2C
>
> Async Serial data 7.933054 8.25E-05 0xB0
>
> Async Serial data 7.933141 8.25E-05 0x7E
>
> Async Serial data 7.933228 8.25E-05 0x7E
>
> Async Serial data 7.933315 8.25E-05 0x80
>
> Async Serial data 7.933402 8.25E-05 0x21
>
> Async Serial data 7.933488 8.25E-05 0x03
>
> Async Serial data 7.933575 8.25E-05 0x01
>
> Async Serial data 7.933662 8.25E-05 0x00
>
> Async Serial data 7.933749 8.25E-05 0x0A
>
> Async Serial data 7.933836 8.25E-05 0x03
>
> Async Serial data 7.933922 8.25E-05 0x06
>
> Async Serial data 7.934009 8.25E-05 0x0A
>
> Async Serial data 7.934096 8.25E-05 0x81
>
> Async Serial data 7.934183 8.25E-05 0x4B
>
> Async Serial data 7.93427 8.25E-05 0x67
>
> Async Serial data 7.934356 8.25E-05 0xCA
>
> Async Serial data 7.934443 8.25E-05 0xA1
>
> Async Serial data 7.93453 8.25E-05 0x7E
>
> Async Serial [1] data 7.939163 8.25E-05 0xFF
>
> Async Serial [1] data 7.939251 8.25E-05 0x03
>
> Async Serial [1] data 7.939339 8.25E-05 0x80
>
> Async Serial [1] data 7.939427 8.25E-05 0x21
>
> Async Serial [1] data 7.939515 8.25E-05 0x03
>
> Async Serial [1] data 7.939603 8.25E-05 0xFD
>
> Async Serial [1] data 7.939691 8.25E-05 0x00
>
> Async Serial [1] data 7.939779 8.25E-05 0x0A
>
> Async Serial [1] data 7.939867 8.25E-05 0x03
>
> Async Serial [1] data 7.939955 8.25E-05 0x06
>
> Async Serial [1] data 7.940043 8.25E-05 0x00
>
> Async Serial [1] data 7.940131 8.25E-05 0x00
>
> Async Serial [1] data 7.940219 8.25E-05 0x00
>
> Async Serial [1] data 7.940307 8.25E-05 0x00
>
> Async Serial [1] data 7.940395 8.25E-05 0x6B
>
> Async Serial [1] data 7.940483 8.25E-05 0x1A
>
> Async Serial [1] data 7.940571 8.25E-05 0x7E
>
> Async Serial [1] data 7.941107 8.25E-05 0xFF
>
> Async Serial [1] data 7.941195 8.25E-05 0x03
>
> Async Serial data 7.9412 8.25E-05 0x7E
>
> Async Serial [1] data 7.941283 8.25E-05 0x80
>
> Async Serial data 7.941287 8.25E-05 0x80
>
> Async Serial [1] data 7.941371 8.25E-05 0x21
>
> Async Serial data 7.941374 8.25E-05 0x21
>
> Async Serial [1] data 7.94146 8.25E-05 0x01
>
> Async Serial data 7.94146 8.25E-05 0x01
>
> Async Serial data 7.941547 8.25E-05 0xFE
>
> Async Serial [1] data 7.941548 8.25E-05 0x02
>
> Async Serial data 7.941634 8.25E-05 0x00
>
> Async Serial [1] data 7.941636 8.25E-05 0x00
>
> Async Serial data 7.941721 8.25E-05 0x04
>
> Async Serial data 7.941808 8.25E-05 0x48
>
> Async Serial data 7.941894 8.25E-05 0x5F
>
> Async Serial data 7.941981 8.25E-05 0x7E
>
> Async Serial [1] data 7.942683 8.25E-05 0x0A
>
> Async Serial [1] data 7.942771 8.25E-05 0x03
>
> Async Serial [1] data 7.942859 8.25E-05 0x06
>
> Async Serial [1] data 7.942947 8.25E-05 0x0A
>
> Async Serial [1] data 7.943035 8.25E-05 0x81
>
> Async Serial [1] data 7.943123 8.25E-05 0x4B
>
> Async Serial [1] data 7.943211 8.25E-05 0x67
>
> Async Serial [1] data 7.943299 8.25E-05 0xFD
>
> Async Serial [1] data 7.943387 8.25E-05 0xC1
>
> Async Serial [1] data 7.943475 8.25E-05 0x7E
>
> Async Serial data 7.944092 8.25E-05 0x7E
>
> Async Serial data 7.944178 8.25E-05 0x80
>
> Async Serial data 7.944265 8.25E-05 0x21
>
> Async Serial data 7.944352 8.25E-05 0x02
>
> Async Serial data 7.944439 8.25E-05 0x02
>
> Async Serial data 7.944526 8.25E-05 0x00
>
> Async Serial data 7.944612 8.25E-05 0x0A
>
> Async Serial data 7.944699 8.25E-05 0x03
>
> Async Serial data 7.944786 8.25E-05 0x06
>
> Async Serial data 7.944873 8.25E-05 0x0A
>
> Async Serial data 7.94496 8.25E-05 0x81
>
> Async Serial data 7.945046 8.25E-05 0x4B
>
> Async Serial data 7.945133 8.25E-05 0x67
>
> Async Serial data 7.94522 8.25E-05 0xEA
>
> Async Serial data 7.945307 8.25E-05 0x5B
>
> Async Serial data 7.945394 8.25E-05 0x7E
>
> Async Serial [1] data 7.949159 8.25E-05 0xFF
>
> Async Serial [1] data 7.949247 8.25E-05 0x03
>
> Async Serial [1] data 7.949335 8.25E-05 0x80
>
> Async Serial [1] data 7.949423 8.25E-05 0x21
>
> Async Serial [1] data 7.949511 8.25E-05 0x02
>
> Async Serial [1] data 7.949599 8.25E-05 0xFE
>
> Async Serial [1] data 7.949687 8.25E-05 0x00
>
> Async Serial [1] data 7.949775 8.25E-05 0x04
>
> Async Serial [1] data 7.949863 8.25E-05 0x3E
>
> Async Serial [1] data 7.949951 8.25E-05 0x54
>
> Async Serial [1] data 7.950039 8.25E-05 0x7E
>
>
>
>
> Op ma 7 jun. 2021 om 16:19 schreef Bas Prins
> <bas.prins3@gmail.com <mailto:bas.prins3@gmail.com>>:
>
> 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
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
> ------------------------------------------------------------------------------
>
>
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