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

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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

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--- In , 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

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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

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--- In , 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.

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peterburdine <> wrote: --- In , 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. Yahoo! Groups SponsorADVERTISEMENT --------------------------------- Yahoo! Groups Links To --------------------------------- [Non-text portions of this message have been removed]

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