Sorry for the long delay until I reported back. I have done more bughunting, fixing, and testing, with the following results: The driver now resets the sensor once a heater stability error occurs more than 30 seconds after the most recent reset. That has the effect that not all ten configurations are affected by the error, but typically only one of them: 370°C (or sometimes 310°C) in case of the sensor that is affected most often, normally 250°C in case of another one. The third one seems to be OK now - but it is used as a reference outside the experimental setup. The issue shows up spontaneously, persists for minutes or hours across many resets, but eventually disappears again during long measurements in fresh air. A different, more important case: All 10 heater configurations (400°C~130°C) become unstable when the sensors are suddenly exposed to a high concentration of VOCs or CO, e.g. vaporized gasoline or alcohol, or burning plastic. They are beyond a 0.5µm particle filter, so soot should not be an issue. Reset has no effect - the issue only disappears when the concentration gets lower again. Is there any known reason why a high VOC concentration (or sudden rise in concentration) might make the heater unstable? As I understand it, heater resistance regulation and gas sensor resistance measurement should be two distinct things, although the two parts are of course in close proximity. Do you think the problem can be addressed by increasing the heater time above 50ms? Are there better suggestions? I'd be glad to hear them. Thank you in advance.
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