The x16 or 圆4 baud rate clock or clock enable is to more precisely resolve the timing of the centre of each bit period for capturing the received bit accurately, and in turn increase tolerance for timebase mismatches between the serial transmitter and the serial receiver.Īny timebase mismatches accumulate over 10 bit periods, beginning with detection of start bit. Ask yourself the following question: what is the integer value of the bit vector ''? Yeh I figure it out nowThank you. So instead of doing something absurd, like comparing a counter value to '' you can compare it towhich makes a lot more sense to us humans. Too many derived clocks, too many signals on sensitivity lists that do not belong there, etc. You should be able to knock out a UART design while you are sleeping. YesI am using Spartan 3E starter kit What is the point of submitting - for your school assignment - code which you do not undestand? Sometimes that suggests a poor understanding of the code being discussed.

I am worried that you don't respond to questions which are meant to be helpful. But if you keep insisting that I'm annoyed, that would be annoying. Here is a more comprehensive Wiki article. What does it benefit you for me or someone else to say 'yes that is right' or 'no that is wrong' if you don't understand how your design works? Here is a simple explanation page. I strongly suggest that you learn how a UART works, understand your design, and troubleshoot it yourself. Should this output be right? I thought for Uart it's then stop Anyway I need to Thank you so much for answering my question Bobyou are like light in the tunnel. A simple test is to bring the baudrate x16 clock to an output pin, and measure the period or frequency with an oscilloscope. Have you simulated this? You might find that troubleshooting the innards of your logic is much simpler with the help of a proper logic simulator.Īye Bob, after I change the numbers tothe hyperterminal doesn't comes out numbers anymore. Without the BUFG buffer, your logic will be eaten alive by clock skew. If the baudrate x16 clock is not buffered and distributed through a BUFG clock buffer, all bets are off for proper function. Another bad coding practice example in the Xilinx code is the use of derived clocks rather than derived clock enables. I believe you are wrong by a factor of 2. As rc has deduced, your baudrate x16 clock divider is wrong. For your sake as well as ours, please rise above the example set by others. You have duplicated this absurd practice along with some of the code. Aye I am currently trying to use XAPP, from Xilinx to transmitt a Zero to PC but it didn't work really well, but it keep sending out random character on hyperTerminal, can anyone tell me what did i do wrong? View solution in original post.

Uart vhdl code