I'm building my own data acquisition system and I want to include Wbo2 logging. I am collecting info on how to control the LSU sensor.
I don't fully understand something in the Wbo2 comments (maybe an error?). In the Vs amplifier part, the code is Wbo2.nernst_target=0x8d. The first stage gain is, based on the schematic, Uout= 5 - ((5-Vs) x 4.6). For our application, we have 5-((5-4.45) x 4.6) = 2.47V => 0x7E and not 0x8D like in the code
- wbo2_nernstdc_target is not wired in the code, but configurable
- "edgetime correction" makes the case a bit more complex than that (otherwise 0x7E would be right).
An other thing I can't understand: How do you calculate the real Ip in the sensor only, without knowing the sensor's resistance. A part of the current generated by the OPA is flowing also in the 10k resistor. With my sensor, I measure 4.7V at pump+ => 0.7/10000 = 70uA. Compared to Ipumptotal = 3.64mA : 0.07/3.64 = 1.9%
- but the error (cause by this) is much smaller than this, because the pump resistance is consistent with Ri resistance and the 10k resistor is also there during calibration. The 10k could be removed but it seems to me the gains are nowhere near the risk.
Where can I find the table lambda=f(Ip) ?
- in wbo2.c ip_to_afr
I suggest to contact the team, especially MembersPage/JörgenKarlsson.
Also, maybe you could consider to share some of your developments or tuning (like PID tuning) if you make experiments (not necessarily fully publicly, if you like, but among core developers). Or even co-develop some gizmo together, you could benefit from the manufacturing capabilities and cooperation between your units and VEMS units, and cooperation with other developers.