I will soon be attempting to interface this HH10D humidity sensor with a dsPIC30f4011. It seems that you get the relative humidity value from measuring the frequency output of one pin, while the other 2 pins are for the spi interface to give you calibration data for a more accurate reading.

First off, the sensor has a working voltage range of 2.7-3.3 Volts while my dspic is running off 5V. If I used the spi interface would I have logic level problems that is hazardous to the chip, or do I have to do a 3.3 to 5V logic shift for all incoming values? Also, would I have to logic shift the frequency output? It is important to note that at other forums there was talk that it is in fact the I2C protocol instead of spi.

Thanks for any help.

 

it is I2C protocol
You will need a level shifter

 

I see. Any recommendations on a suitable mosfet for this. I came across sources that said to use bss and bsn type but the packages were surface mount or they are out of production. I'm looking for through hole. thanks!