The current implementation is renamed to tcp-rigol as it seems to be
a Rigol proprietary protocol used only on Rigol VS5000 series.
A new tcp-raw implementation is introduced which simply carries raw SCPI
commands over TCP. It is probably a much more common protocol and it is
at least available on Rigol DS2000 series on port 5555.
This allows a frontend to initialize a session file, providing the
required samplerate and probe names, without having a proper
struct sr_dev_inst handy.
sr_session_append() is then used to add captured data to the session
file, as usual.
The existing sr_session_save() function works the same way as always.
Most messages from the DMM parsers are not hard errors, lower to
sr_dbg() so that the sigrok-cli output doesn't get cluttered (by default)
with debug output such as:
P1: 0.001100 V DC AUTO
sr: fs9721: Sync nibble in byte 0 (0x00) is invalid.
P1: 0.001100 V DC AUTO
(using -l 4 or -l 5 will still allow the user to see such messages)
The sample buffer is a still a bit of a mystery, but this should help.
The variables in play:
triggerbar/ramsize_trigger - These two variables added together indicate
how many samples we want captured. ramsize_trigger - triggerbar
indicades how many samples must be captured. The ratio between the two
is determined by capture ratio.
memory_size - This indicates the number of samples in the circular
capture buffer. stop_address, now_address, and trigger_address are
pointers within the zeroplus that wrap based on this size.
now_address - The address that the zeroplus was about to write to when
it finished capturing, and now the address that will be read from when
reads are done from the capture buffer
stop_address - The address that the zeroplus last wrote to when it
completed capture.
trigger_address - The sample address for which the trigger occured.
status - This one is a bit tricky. Some testing has shown that if the
zeroplus has captured memory_size or less samples, the STATUS_READY bit
is set. For all captures generated with more samples than this,
STATUS_READY was cleared. However, boundary conditions are difficult to
test and values such as, memory_size + 1 have not been tested. We use
this to determine if the capture has wrapped through the sample buffer.
More testing is required, but this improves behavior in a number of
cases, specifically capturing sample amounts that are not a power of 2
of the sample buffer size. Before, random data was passed to libsigrok.
Signed-off-by: Russ Dill <Russ.Dill@gmail.com>