sailek:
I am trying to connect HT9032D with arduino. The Dout pin is connected to the RX pin on the arduino. The circuit setup is exactly same as in the datasheet. Still I'm not getting any reading from the RX pin. Can someone tell me where the mistake is found.
Well, I don't see anything in the datasheet regarding the protocol of either the DOUT or DOUTC outputs. So, to assume the protocol is TTL level RS232, might be an error.
Have a look at this Application Note from Holtek -- scroll down to the Serial Interface section at the bottom of the document -- that seems to be the most likely place to get insight on the protocol: http://www.holtek.com.tw/documents/10179/116745/an0053e.pdf
I searched the above document for the term "RS232" and found nothing, so this may be a proprietary protocol, and if so, you might have to roll your own receiver, in software.
BTW: are you seeing any kind of signal occurring at the DOUT or DOUTC outputs? That would at least give you an indication of whether or not this thing is decoding anything.
UPDATE: It looks like what this thing is doing is translating the FSK signal into a TTL bit stream. So, more than likely, the protocol information is all in sections regarding what it's receiving. I just briefly scanned the document, so I can't say for sure -- in depth reading is your job 