baud rate generation dedicated to USART issues??

[mohi@608]

i am a bit confused in USART design . my issue is that at the reciver end in USART , whether to have a baud rate detection block or have a single baud rate generation block for transmit and receive ??

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and when do we use baud rate detection ?? and can it be used in the USART???

 

[not-a-moderator]

You usually set up the USART receiver with the correct (if known) baud rate, stop bits etc. as what the transmitter is using to transmit the data.

Baud rate detection refers to the process by which a receiving device (such as a USART) determines the speed, code level, and stop bits of incoming data by examining the first character, usually a preselected sign-on character (also called a "syncword").
It allows the receiving USART to accept data from a variety of transmitting devices operating at different speeds without needing to establish the data rates in advance.

You will need to set up your processor's baud rate generation block (USART Parameter Registers) before you can transmit from it?

 

[gabryponte]

mybe I can not give a full answer, but you can have a look of what other uP do.
For example, if you look at a PIC18f45k20, at page 253, there are the AUTO-BAUD detect for the onboard EUSART.

 

[mohi@608]

the traditional 16x baud rate generator is having higher error% as compared to fractional baud rate generator . I am thinking to design a fractional baud rate generator but not clear how the fractional counter will work..?? could anyone help me in that...