# How does the PT2264 determine how many address pins are in use?

So, I'm looking into making a little device which uses an 433MHz transmitter and a PT2264 or LP801B.

While reading the datasheet for the PT2264, I'm a little confused on how it is determined, how many of the pins are used for address and data.

Pins 10, 11, 12, and 13 are combined pins, either used as address pins or data pins.

• pin 10: address pin 8 or data pin 3
• pin 11: address pin 9 or data pin 2
• pin 12: address pin 10 or data pin 1
• pin 13: address pin 11 or data pin 0

The datasheet is quite weirdly worded how it is determined whether these pins are used for address or data. Page five of the datasheet exemplifies the various combinations, but it isn't clear how I actually select the data type.

The address pins can be used in a tri-state fashion, so either shorted to Vcc, to ground, or left floating.

It almost seems, as if the chip detects the number of address bits, but checking what last floating pin is used, and assigning the rest as data. Although I'm not sure at all about this, as it's never stated in the datasheet like that.

Assuming I have set the pins to the following settings (Code word as they call it in the datasheet):

[ 1 f f 0 f f f f 0 1 0 0 ]


(f is the tri-state floating) Now my understanding is, that [ 1 f f 0 f f f f ] is the address part and [ 0 1 0 0 ] is the data sent to that address.

But according to the datasheet, it might as well be all the address in a zero-stand-by transmitter mode.

Another way of distinguishing whether the four combined pins are address or data pins, is by using pull-down resistors, as shown in the datasheet as well, but again - I'm not sure about this either.

So if anyone could clear this up, that would be very nice.

Perhaps one little extra-question: are the PT2264 and LP801B devices equivalent? I could only find the datasheet for the LP801B in Chinese, and translating it with online tools is very hit and miss. It seems they're equivalent, but I'd love to know for sure.