testbench of serial interface(UART)

[Smith]

Hi, all.
Thanks for this site which helps me a lots by the helps given by you
all.
Cox im a newbie in the HDL design, so hope u all can clear some of my
doubts. Thanks advance.

I'm now trying to implement my design which is the UART serial
interface with 8-bit data as the input. I'm now using the Virtex 2
prototyping board to implement and proof my design. Besides that, I'm
planning to use the LEDs on the board to show the output of the system.

As I know, I need to feed my design with proper waveform which indicate
the 8-bit data input to the UART design, however I can not use the way
I learned before which is using a counter to generate the string of
data as the input feeding to the UART as it will not work directly.

Can someone point out the right way to generate the proper waveform
which can be used to feed the UART input? Is that a proper way to use
the LEDs to show the output of the UART?

Thanks again for the help.

 

[Mike Treseler]

Smith wrote:

Can someone point out the right way to generate the proper waveform
which can be used to feed the UART input? Is that a proper way to use
the LEDs to show the output of the UART?

The quick and dirty way is to loop back
transmit output to the receive input.
See the testbench and waves here:
http://home.comcast.net/~mike_treseler/
It's in vhdl, but it might give you some ideas.

-- Mike Treseler

 

[mk]

On Wed, 14 Jun 2006 10:57:04 -0700, Mike Treseler
<mike_treseler@comcast.net> wrote:

Smith wrote:

Can someone point out the right way to generate the proper waveform
which can be used to feed the UART input? Is that a proper way to use
the LEDs to show the output of the UART?

The quick and dirty way is to loop back
transmit output to the receive input.

Another is to instantiate two UART and different input clock
frequencies (where the difference is less than allowed ppm of course)
and transmit with one and receive with the other. Of course this only
guarantees that your UART can talk to itself ;-) Ideally you need to
find a third party UART and test your transmit and receive sides
individually with it.

 

mk wrote:

On Wed, 14 Jun 2006 10:57:04 -0700, Mike Treseler
mike_treseler@comcast.net> wrote:

Smith wrote:

Can someone point out the right way to generate the proper waveform
which can be used to feed the UART input? Is that a proper way to use
the LEDs to show the output of the UART?

The quick and dirty way is to loop back
transmit output to the receive input.

Another is to instantiate two UART and different input clock
frequencies (where the difference is less than allowed ppm of course)
and transmit with one and receive with the other. Of course this only
guarantees that your UART can talk to itself ;-) Ideally you need to
find a third party UART and test your transmit and receive sides
individually with it.

You could instantiate two UARTs in your FPGA. One UART would be
transmit only and the other is receive only. The output of the receive
UART drives the input of the transmit UART _and_ also drives the LEDs.
Using Window's Hyperterminal, what you type on the PC is sent to the
receive UART, displayed on the LEDs, and sent back to the PC via the
transmit UART. The buad rates for both UARTs must be the same as the
baud rate for the PC serial port.

HTH
-Dave Pollum

 

[Smith]

Thanks for your material. I'll study on it. Thanks...
Mike Treseler wrote:

Smith wrote:

Can someone point out the right way to generate the proper waveform
which can be used to feed the UART input? Is that a proper way to use
the LEDs to show the output of the UART?

The quick and dirty way is to loop back
transmit output to the receive input.
See the testbench and waves here:
http://home.comcast.net/~mike_treseler/
It's in vhdl, but it might give you some ideas.

-- Mike Treseler