/b

Do you expect that the serial controller do support 14-bit mode? You haven't even specified exactly which chip you intend to use.

A software-only implementation, constantly peeking at a digital pin must also know the chip to know how it should count time - unless you are talking about a synchronous 14-bit transfer protocol, in which case the code must look at more than one signal.

Or where you planning on the code to auto-detect baudrate?

i used 89s52

and i know that it not supports the 14 bit receive mode

so i ask u

is it any way to receive 14 bits on rxd

So what on earth is "/b" supposed to mean as the title for your question?

First, you need a proper specification for this "14-bit data"; eg,

Is it asynchronous, with, say, 1 start bit, 14 data bits, 1 stop bit?

Or is it sychronous, with some clock signal somewhere?

Or what?

It is really impossible to answer your question without such essential details!

yes 14 asynchronous bits
in that 1 start 12 databits and 1 stop bits

i have to make wireless system in which i use rf module.

in tx i use encoder which generate the 1 start bit than after 8 address bit than after 4 databits than after 1 stop bit. and it sends it serially to the rf tx module.

rf recever module's receive bit is directly connect to the rxd of 89s52

i come 1st time on this mexxage board to ask something

i never come here.

but i have problem to day so i come here

so dont know hw to use it so i used the heading /b

"start 12 databits and 1 stop bits"

No, there is no standard 8051 hardware feature to handle that.
In fact, I'm not sure that there's any standard UART at all which could handle that?

You should contact the module supplier for suggestions!

Try searching for "Software UART" or "Soft UART" - and adapt that code to the required number of bits.

"Bit-bang" would be another keyword for searching...

"dont know hw to use it"

So read the Instrucions!

http://www.keil.com/forum/

http://www.keil.com/forum/tips.asp

"so i used the heading /b"

Why did that seem appropriate to you??
What is the meaning or significance of "/b"

thanksssssssss

How about a link to the datasheet for the thingy that send the data you need to receive.

That should anable any willing soul to help you.

Erik