What can be determined by looking at serial waveform ?

Post discussions on projects you are working on
Post Reply
nurber
Active User
Active User
Posts: 12
Joined: Fri Mar 24, 2017 6:05 pm

What can be determined by looking at serial waveform ?

Post by nurber »

Hi Forum. I was evaluating a communication protocol on a bus trying to isolate some attenuation at the assorted locations of bus when I realized how poor my skills at interpreting a waveform when I don't know the protocol. The only thing I could determine about this waveform is ~9.5VDC between center conductor and shield of coax with some serial comms on top of the 9.5V, but I wonder how others decode this ? Any good online resources for how to approach decoding unknown protocols appreciated.

Sven

nurber
Active User
Active User
Posts: 12
Joined: Fri Mar 24, 2017 6:05 pm

Re: What can be determined by looking at serial waveform ?

Post by nurber »

like so many times before attachments seem problematic on this forum. I tried uploading a 4.8MB psdata of relevant serial waveform, but receive a message about "HTTP Error"

nurber
Active User
Active User
Posts: 12
Joined: Fri Mar 24, 2017 6:05 pm

Re: What can be determined by looking at serial waveform ?

Post by nurber »

and it happens with both Chrome and Firefox...

Martyn
Site Admin
Site Admin
Posts: 4543
Joined: Fri Jun 10, 2011 8:15 am
Location: St. Neots

Re: What can be determined by looking at serial waveform ?

Post by Martyn »

We are aware of an issue for some users when posting attachments, and are looking into why this is happening again.

With respect to the data file, if you send it to support@picotech.com I can post it for you so that others can download it.
Martyn
Technical Support Manager

Martyn
Site Admin
Site Admin
Posts: 4543
Joined: Fri Jun 10, 2011 8:15 am
Location: St. Neots

Re: What can be determined by looking at serial waveform ?

Post by Martyn »

Here is the file
Attachments
20240508 Full Tilt.psdata
(4.56 MiB) Downloaded 292 times
Martyn
Technical Support Manager

Martyn
Site Admin
Site Admin
Posts: 4543
Joined: Fri Jun 10, 2011 8:15 am
Location: St. Neots

Re: What can be determined by looking at serial waveform ?

Post by Martyn »

There looks to be three different pulse widths in that signal, maybe this is duty cycle signalling, and as the file is named full tilt you are at the top of the range. If you add in a Maths channel for posduty(B) and then run at half tilt does the duty cycle change?
Martyn
Technical Support Manager

bennog
Advanced User
Advanced User
Posts: 212
Joined: Mon Nov 26, 2012 9:16 am
Location: Netherlands

Re: What can be determined by looking at serial waveform ?

Post by bennog »

looks like a 13uS variable lengt bit strem (about 76.5 kbps)
The voltage drop to 9.5V seems to signal end of data.
Could also be a space of more than 5 bits.

Benno

nurber
Active User
Active User
Posts: 12
Joined: Fri Mar 24, 2017 6:05 pm

Re: What can be determined by looking at serial waveform ?

Post by nurber »

Thanks for interpreting the waveform Martyn and Benno

Post Reply