This makes 'output_frequency' symmetrical with 'output_current' and
'output_voltage'. On a more fundamental level, there's no reason why
frequency should be treated as a discrete quantity, other than
"es51919 used it this way".
Since every individual measurement is represented by a single frame
and a "sample" isn't all that meaningful concept in this context,
it makes more sense to define possible limit in number of frames.
Make the es51919 driver to support setting a frame limit instead of
a sample limit.
In most, but not all, modes the ES51919 reports two separate
analog values for each measurement sample. These values are
mapped to two separate channels and sent in two separate
packets.
A client program needs a way to determine which results are
parts of the same measurement and also know when a complete
measurement is received so it can process the sample. Use
the frame begin and end packets to separate groups that each
represent a single complete measurement.
Use g_malloc0() for small allocations and assume they always
succeed. Simplify error handling in a few places accordingly.
Don't always sanity-check parameters for non-public (SR_PRIV)
functions, we require the developers to invoke them correctly.
This allows further error handling simplifications.
The automatic selections of the measured quantity and equivalent circuit
model are more part of the configuration of the meter than attributes
of the measurement result. To reflect this, model them as config keys
instead of mqflags. This allows a driver that supports remote control to
implement 'set' method for them and has the additional benefit of saveing
two flag bits.
Add a protocol decoder for the Cyrustek ES51919 LCR meter chip.
This chipset (together with ES51920 front-end) is supposedly used
by multiple different portable LCR meters including at least
DER EE DE-5000, Yihua V&A VA520, Mastech MS5308, Uni-T UT612,
CEM DT-9935 and various OEM rebadges of them.
The communication protocol seems to be implemented on the Cyrustek
chip itself so all the different models are expected to use the
same protocol if they implement a host connection. Unfortunately
the protocol is not available in the public documentation of the
chipset, so this implementation is based on reverse engineering it
from traffic captures.
The actual connection between the meter and the host computer may be
different from meter to meter even when based on the same chip. This
module implements a decoder for the protocol and some common helper
functions for interfacing with the meter via an RS-232 serial port.
Alexandru Gagniuc
Uwe Hermann
Martin Ling
Janne Huttunen
Bert Vermeulen