Hi I am Nandinikrishna I am working on C8051CF023 processor. How exactl does synchronous and asynchronous communication take place. To transmit bit the TXD line will be held low ie.,0V, to transmit 1 bit the TXD lin will be held at 5v. In asynchronous communication the processing speed o the two terminal varies then how long should the TXD line be supplied wit the voltage?
UART communication doubt
Jan 30, 2008
4 Replies
It's not a doubt, its a question, as someone said before. I think what you are getting at is "how does a UART retain sync when the clock rates at the ends are bound to be different?" The answer is that the hardware starts a counter, clocked at several times the Baud rate (usually
8-16x), when the start bit arrives, and uses that as a relative reference to gauge the sampling point of the data. So as long as the clocks aren't too far out relative to each other, and as long as the data word isn't too long, by the time the stop bit arrives the bit level is still valid at the sampling point. Then the whole lot gets resychronised by the next start bit.
My doubt is whether gmail users understand how the internet and even books work for basic research purposes!!!
One could conceive of having internet access but not access to books. Having a gmail account without having access to the web and Google would be a bit more improbably.
Grant Edwards grante Yow! Am I in Milwaukee?
at
visi.com
Doubt is fine. Surely you can adapt your phraseology to that of something like 500 million English speaking Indians? And others. Pure English is only spoken in Canada, and only in parts thereof, where it has been preserved against the viscissitudes of vicious fortunes for generations. :-)
The point is that the communications speed is normally pre-agreed by some means outside the channel, and thus is pre-known to the hardware.
[mail]: Chuck F (cbfalconer at maineline dot net)
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Try the download section.
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