Learning About xoscope

Here are my notes about learning to use xoscope a "digital oscilloscope for Linux".

My initial success was to capture the "clock" and "ping" traces seen on my Learning About Skannerz Racerz page.

I constructed a single-channel "probe" from a stereo plug audio cable connected to two alligator clips via a terminal block. I also used a resistor on the positive probe.

@@ TODO: Illustrate and detail probe

The command line invocation I used (see man page or docs for details):

   xoscope -1 0 -m 1 -v

Additional support hardware

• Buffer Hardware for xoscope

• Further description of buffer

• Oscope Buffer Circuit Pictures

Other links

• One person's xoscope experience -- contains notes including initial probe creation, command line options and setting up line-input capture.

• Question about xoscope and probe creation (Google cache)

• This post about xoscope display speed mentions a patch to fix a hard-coded display update rate, but unfortunately the link is dead:

Put up a new verson which is speed limited to 85 fps (my refresh rate)
and only uses abou 6% cpu. If you want to change the fps just go into
display.c and change the fps variable to suit. Should make it a command
line option I guess.
http://home.pacific.net.au/~greendog/xoscope/xoscope-1.8.1.tar.gz 

• There is discussion in the INTERNALS document about a related issue and command-line switch "-i" that doesn't seem documented elsewhere:

Next, a limit is placed on how often screen updates occur.  The
min_interval parameter specifies the minimum interval (in
milliseconds) that must pass between screen updates.  As explained in
the display.c:show_data() function, updates at the end of the trace
will be performed more frequently to insure that partial traces are
not drawn on the screen.  The default min_interval is 50 milliseconds,
corresponding to a 20 Hz update rate, and can be adjusted using the
command line switch '-i'.  A good way to both test this code and see
its effects is to specify '-i 1000' which decreases the update rate to
a clearly visible 1 Hz.  If this code isn't working right, the net
result is the X server consuming all the CPU's available time.

• Some discussion about the xoscope buffer circuit in a thread about an Atmega-based oscilloscope.