Issues on clockless uart

Hi,
I'm doing a project in clockless uart..as u know that the primary
function of uart is parallel to serial conversion while transmitting
and serial to paralel conversion while receiving..I was wondering if
someone could tell me as how can i do a parallel to serial conversion
and vice versa without using a clock.

Note: This is a circuit whoch doesnt use a clock at all/ Asynchronous
Circuit/Clockless Circuit.

Thank You
SHASHI

Shashi wrote:

> Hi,
> I'm doing a project in clockless uart..as u know that the primary
> function of uart is parallel to serial conversion while transmitting
> and serial to paralel conversion while receiving..I was wondering if
> someone could tell me as how can i do a parallel to serial conversion
> and vice versa without using a clock.
> 
> Note: This is a circuit whoch doesnt use a clock at all/ Asynchronous
> Circuit/Clockless Circuit.
> 
> Thank You
> SHASHI

 you don.t use a clock for asynchronous data.

Do you mean without a baudrate clock?  If so, good luck.
Usually UARTs don't have a clock line used for communications,
since they are asynchronous, but they do use a clock internally
to generate the output data stream, or to sample the incoming
data.

Mike Anton

"Shashi" <shashi22k@rediffmail.com> wrote in message
news:7cdabebf.0404211144.38da229c@posting.google.com...
> Hi,
> I'm doing a project in clockless uart..as u know that the primary
> function of uart is parallel to serial conversion while transmitting
> and serial to paralel conversion while receiving..I was wondering if
> someone could tell me as how can i do a parallel to serial conversion
> and vice versa without using a clock.
>
> Note: This is a circuit whoch doesnt use a clock at all/ Asynchronous
> Circuit/Clockless Circuit.
>
> Thank You
> SHASHI

Shashi wrote:
> Hi,
> I'm doing a project in clockless uart..as u know that the primary
> function of uart is parallel to serial conversion while transmitting
> and serial to paralel conversion while receiving..I was wondering if
> someone could tell me as how can i do a parallel to serial conversion
> and vice versa without using a clock.
> 
> Note: This is a circuit whoch doesnt use a clock at all/ Asynchronous
> Circuit/Clockless Circuit.

You could do it with a string of one-shots, but
I feel guilty just suggesting such a grotesque
kludge.

I just put my finger down my throat and now I
feel much better.

> I was wondering if
> > someone could tell me as how can i do a parallel to serial conversion
> > and vice versa without using a clock.
> > 
> > Note: This is a circuit whoch doesnt use a clock at all/ Asynchronous
> > Circuit/Clockless Circuit.
>

Use a tapped delay line.

Inject a pulse to start, then time everything downstream off the
taps.

Loop the pulse back as necessary to extend the delay.

"Shashi" <shashi22k@rediffmail.com> escribi&#4294967295; en el mensaje
news:7cdabebf.0404211144.38da229c@posting.google.com...
> Hi,
> I'm doing a project in clockless uart..as u know that the primary
> function of uart is parallel to serial conversion while transmitting
> and serial to paralel conversion while receiving..I was wondering if
> someone could tell me as how can i do a parallel to serial conversion
> and vice versa without using a clock.
>
> Note: This is a circuit whoch doesnt use a clock at all/ Asynchronous
> Circuit/Clockless Circuit.
>
> Thank You
> SHASHI

and how are you planing to "sample" the input bits without a clock?, if you
already figured out that part, then i guess you could use some sort of state
machine ("clocked" or controled by the same circuit that sampled the bits)
to deserialise those sampled bits.
what kind of UART is it anyway?, and what kind of coding uses? does it use a
selfclocking code scheme?

"Shashi" <shashi22k@rediffmail.com> wrote in message
news:7cdabebf.0404211144.38da229c@posting.google.com...
> Hi,
> I'm doing a project in clockless uart..as u know that the primary
> function of uart is parallel to serial conversion while transmitting
> and serial to paralel conversion while receiving..I was wondering if
> someone could tell me as how can i do a parallel to serial conversion
> and vice versa without using a clock.
>
> Note: This is a circuit whoch doesnt use a clock at all/ Asynchronous
> Circuit/Clockless Circuit.
>
> Thank You
> SHASHI

As serial output is in the time domain, you must use a timer. If you really
don't want to use a clock then take your circuit diagram, remove the word
"clock" and replace it with the words "timer/counter".

Peter


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"Shashi" <shashi22k@rediffmail.com> wrote in message
news:7cdabebf.0404211144.38da229c@posting.google.com...
> Hi,
> I'm doing a project in clockless uart..as u know that the primary
> function of uart is parallel to serial conversion while transmitting
> and serial to paralel conversion while receiving..I was wondering if
> someone could tell me as how can i do a parallel to serial conversion
> and vice versa without using a clock.
>
> Note: This is a circuit whoch doesnt use a clock at all/ Asynchronous
> Circuit/Clockless Circuit.
>
> Thank You
> SHASHI

If you're not trying to do an RS232 standard UART, you could use another
standard
that includes the clock in the data stream.  There many other standards that
allow
you to derive the clock from the data stream.

Or, did you mean an auto-bauding UART?  Where the UART can derive the baud
rate based on the assumption that it is receiving the characters "AT"?

--Anthony

In comp.arch.embedded, Jim Stewart <jstewart@jkmicro.com> wrote:

>Shashi wrote:
>> Hi,
>> I'm doing a project in clockless uart..as u know that the primary
>> function of uart is parallel to serial conversion while transmitting
>> and serial to paralel conversion while receiving..I was wondering if
>> someone could tell me as how can i do a parallel to serial conversion
>> and vice versa without using a clock.
>> 
>> Note: This is a circuit whoch doesnt use a clock at all/ Asynchronous
>> Circuit/Clockless Circuit.
>
>You could do it with a string of one-shots, but
>I feel guilty just suggesting such a grotesque
>kludge.

   I thought of that too, it seems like an interesting if a bit
bizarre design exercise, but I didn't mention it because the post
smells too much like a homework/class assignment.

>I just put my finger down my throat and now I
>feel much better.

Ben Bradley wrote:
> In comp.arch.embedded, Jim Stewart <jstewart@jkmicro.com> wrote:
> 
> 
>>Shashi wrote:
>>
>>>Hi,
>>>I'm doing a project in clockless uart..as u know that the primary
>>>function of uart is parallel to serial conversion while transmitting
>>>and serial to paralel conversion while receiving..I was wondering if
>>>someone could tell me as how can i do a parallel to serial conversion
>>>and vice versa without using a clock.
>>>
>>>Note: This is a circuit whoch doesnt use a clock at all/ Asynchronous
>>>Circuit/Clockless Circuit.
>>
>>You could do it with a string of one-shots, but
>>I feel guilty just suggesting such a grotesque
>>kludge.
> 
> 
>    I thought of that too, it seems like an interesting if a bit
> bizarre design exercise, but I didn't mention it because the post
> smells too much like a homework/class assignment.

I know.  It is sad because the first computer I *really*
understood was the PDP 8/l, which was a totally asyncronous
design.  Ironically, the only clock in the machine was
for the tty "uart".

If the machine broke in such a way as to stop the
propagation of pulses, you had no way to scope anything.
One of the tricks was to jumper the uart clock to the
start key so you could poke around and find out where
the pulse was getting lost.