Thanks radarman and Duane Clark. I have read that link. It is quite
useful.
I want to make a simple test for transmission data between PC(matlab)
to
FPGA(UART). I can generate the UART.bit file and download into
FPGA
board successfully.
Can I ask a question of user constraint file ? I have successfully
downloaded a LED flash into
FPGA board before. I copied this exercise
from the CD enclosed with the
FPGA board. I remember before I implement
it into
FPGA board. I not only generate the .bit file also copied the
LED user constraint file in the CD. Actually I am not quite sure the
content of the constraint file. I just copied it. Now I want to
implement UART into
FPGA board. I think it also needs one user
constraint file for implementing. I think the user constraint file is
generated automatically when the programming file is generated. But
when I open the .ucf file, it is blank. What is the problem? Shall i
write it by myself? I don't know how to connect the pin? Can you
explain the .ucf function for me clearly? And How does it work and how
does it generate? Actually I have not a clear thread of it. Any
suggestions are appreciated. Thanks again.
\zhi
Duane Clark wrote:
> ZHI wrote:
> > ...
> > I know transmitting these numbers to FPGA board. I need a UART. I have
> > one. I also have done the algorithms in FPGA. But I don't know how to
> > transmit the numbers from Matlab to FPGA. Exactly to say, I don't know
> > how to control uart. How does uart know the data come in? ...
>
> Every byte of data sent via the UART starts with a start bit and ends
> with a stop bit (in the most commonly used scheme, 1 start bit, 1 stop
> bit, no parity). In between transmission of data, the UART holds the
> stop bit level. UART receivers therefore know that no data is being sent
> until it receives a start bit, and it knows that the next 8 bits are data.
>
> All this is handled by the hardware and is largely transparent to you.
> Within the FPGA, the UART receiver will provide a bit indicating that
> data has been received.