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Problem reading AD with upsd3354

I try to read ADC0 to 4 with a upsd3354, but the voltage at the pins P1.0 to 4 (measured with a scope) is always 3V3, and the readed value is 1023.

P1SFS0 and P1SFS1 are equal to 0x1f, to put this inputs in special + ADC.

The signals enter this pins via a serial 100kohm resistor. At the input of this resistor I have 0.9V but between the resistor and the upsd pins I read 3V3.

It looks like if the internal pull-up resistors are enabled ?

Can someone help me ?