Lpc2000

Hi all members:
 
I can get a Rx FIFO depth through FCR register,but how can I calculate the Tx FIFO size.
 
According to the LPC2119 document,this CPU's UART is compatible with the 16c550's which has a certain Tx FIFO size while I cann't find any words about that in philipse's document. 
 
thanks



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[Non-text portions of this message have been removed]

At 04:30 PM 2/25/05 +0800, Hong Jiang wrote:

>Hi all members:
>
>I can get a Rx FIFO depth through FCR register,but how can I calculate the 
>Tx FIFO size.
>
>According to the LPC2119 document,this CPU's UART is compatible with the 
>16c550's which has a certain Tx FIFO size while I cann't find any words 
>about that in philipse's document.

The top of page 140 of the user manual "16 byte Receive and Transmit FIFOs."

Robert

" 'Freedom' has no meaning of itself.  There are always restrictions,
be they legal, genetic, or physical.  If you don't believe me, try to
chew a radio signal. "

                         Kelvin Throop, III

--- In lpc2000@yahoogroups.com, Robert Adsett <subscriptions@a...> wrote:
> At 04:30 PM 2/25/05 +0800, Hong Jiang wrote:
> 
> >Hi all members:
> >
> >I can get a Rx FIFO depth through FCR register,but how can I
calculate the 
> >Tx FIFO size.
> >
> >According to the LPC2119 document,this CPU's UART is compatible
with the 
> >16c550's which has a certain Tx FIFO size while I cann't find any
words 
> >about that in philipse's document.
> 
> The top of page 140 of the user manual "16 byte Receive and Transmit
FIFOs."
> 
> Robert
> 
> " 'Freedom' has no meaning of itself.  There are always restrictions,
> be they legal, genetic, or physical.  If you don't believe me, try to
> chew a radio signal. "
> 
>                          Kelvin Throop, III

I just wish they gave you a way to know how many bytes are in the FIFO
(at least the tx fifo).  In my drivers I just keep track of how many I
put in, and they when I get THRE I reset the count to zero.

--Peter

At 09:11 PM 2/25/05 +0000, peterburdine wrote:
>I just wish they gave you a way to know how many bytes are in the FIFO
>(at least the tx fifo).  In my drivers I just keep track of how many I
>put in, and they when I get THRE I reset the count to zero.

Why?  If you are doing a polled transmission I could see the use for a FIFO 
full flag but for interrupt driven you can stuff the FIFO faster than you 
can remove a byte from it at most baud rates.  Even for polled transmission 
I don't see much loss of efficiency (if there were you could easily switch 
to interrupt driven).  I don't see any use for a FIFO count and I've not 
seen a UART with a FIFO that has one.

Robert



" 'Freedom' has no meaning of itself.  There are always restrictions,
be they legal, genetic, or physical.  If you don't believe me, try to
chew a radio signal. "

                         Kelvin Throop, III

--- In lpc2000@yahoogroups.com, Robert Adsett <subscriptions@a...> wrote:
> At 09:11 PM 2/25/05 +0000, peterburdine wrote:
> >I just wish they gave you a way to know how many bytes are in the FIFO
> >(at least the tx fifo).  In my drivers I just keep track of how many I
> >put in, and they when I get THRE I reset the count to zero.
> 
> Why?  If you are doing a polled transmission I could see the use for
a FIFO 
> full flag but for interrupt driven you can stuff the FIFO faster
than you 
> can remove a byte from it at most baud rates.  Even for polled
transmission 
> I don't see much loss of efficiency (if there were you could easily
switch 
> to interrupt driven).  I don't see any use for a FIFO count and I've
not 
> seen a UART with a FIFO that has one.
> 
> Robert
> 
> 
> 
> " 'Freedom' has no meaning of itself.  There are always restrictions,
> be they legal, genetic, or physical.  If you don't believe me, try to
> chew a radio signal. "
> 
>                          Kelvin Throop, III

Well thats what I meant to get at, there is no way to tell if it is full.

peterburdine <lordofdawn@...> wrote:

--- In lpc2000@yahoogroups.com, Robert Adsett <subscriptions@a...> wrote:
> At 04:30 PM 2/25/05 +0800, Hong Jiang wrote:
> 
> >Hi all members:
> >
> >I can get a Rx FIFO depth through FCR register,but how can I
calculate the 
> >Tx FIFO size.
> >
> >According to the LPC2119 document,this CPU's UART is compatible
with the 
> >16c550's which has a certain Tx FIFO size while I cann't find any
words 
> >about that in philipse's document.
> 
> The top of page 140 of the user manual "16 byte Receive and Transmit
FIFOs."
> 
> Robert
> 
> " 'Freedom' has no meaning of itself.  There are always restrictions,
> be they legal, genetic, or physical.  If you don't believe me, try to
> chew a radio signal. "
> 
>                          Kelvin Throop, III

I just wish they gave you a way to know how many bytes are in the FIFO
(at least the tx fifo).  In my drivers I just keep track of how many I
put in, and they when I get THRE I reset the count to zero.

--Peter

peterburdine:

     Thanks a lot!I'm too careless to find the Tx FIFO size.






 
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---------------------------------
Do You Yahoo!?
150万曲MP3疯狂搜，带您闯入音乐殿堂
美女明星应有尽有，搜遍美图、艳图和酷图
1G就是1000兆，雅虎电邮自助扩容！

[Non-text portions of this message have been removed]