Thanks! The suggested algorithm looks promising. However, if the spikes take place only for those specific cells, is it possible to absorb them into the offset calibration?
No, since they are not constant. The bus segments charge up between readouts with a time constant of about 0.5s. So if you do the readout with 1Hz event rate and with 100Hz event rate, the peaks will differ by a factor up to 10, so a constant offset correction cannot take care of that.