the question is according to interrupt generating when the threshold is used.
According to the datasheet the interrupt will be generated (if the the interrupt is enabled), whe the measurment crosses the threshold.
According to the THRES_EN bits in ADCPOSTx interrupt will be generated when the measurement is LARGER than threshold.
The application require the interrupt to be generated when the measurement cross the threshold (meas > thres) and when the meas < thres.
For example in Si114x this is set via IRQ_MODE register.
The question is:
When the threshold is used(in Si115x), when the interrupt is generated?
Unlike Si114x, Si115x does not have IRQ_MODE register to control interrupt mode. For Si115x, if you set the THRESH_EN bit in ADCPOSTx register, the interrupt will be generated when the sample is larger than the THRESHOLDx value (meas > thres). If the THRESH_EN bit is not set, the interrupt will be generated on every sample.
Unfortunately, Si115x doesn't support the interrupt mode when the sample is smaller than the threshold (meas < thres).