UART x3

I am looking for an PIC with three UART ports if such a thing exists. I
have two UART inputs and I want to output a single UART output. I've seen
plenty of ICs with 2 UART ports, but I have yet to find one with three. I
typically use microchip ICs, but I am open to any brand as long as it
would do the trick and has a good C compiler. 

How would a situation like this be handled in modern electronics? I am a
student and we typically would solve something like this with a MUX.
However, 1) it seems pretty "primitve" for today's electronics - are these
still used? and 2) I would like to use all three UART ports at the same
time. 

I was thinking of two ICs, but with only 2 UARTs that wouldn't solve the
problem. The only other idea I could come up with would be to have an IC
to store the data from each UART input to a memory IC. A third IC would
then read/write from the shared memory and output a single UART output.

Is there anything simple that would solve my problem? I am a software guy
and am not very good with hardware. Any advice or even google search words
would be appreciated. Thanks for the help.

On Nov 17, 12:51 pm, "jonathan03" <jm_2003_2...@yahoo.com> wrote:
> I am looking for an PIC with three UART ports if such a thing exists. I
> have two UART inputs and I want to output a single UART output. I've seen
> plenty of ICs with 2 UART ports, but I have yet to find one with three. I
> typically use microchip ICs, but I am open to any brand as long as it
> would do the trick and has a good C compiler.
>
> How would a situation like this be handled in modern electronics? I am a
> student and we typically would solve something like this with a MUX.
> However, 1) it seems pretty "primitve" for today's electronics - are these
> still used? and 2) I would like to use all three UART ports at the same
> time.
>
> I was thinking of two ICs, but with only 2 UARTs that wouldn't solve the
> problem. The only other idea I could come up with would be to have an IC
> to store the data from each UART input to a memory IC. A third IC would
> then read/write from the shared memory and output a single UART output.
>
> Is there anything simple that would solve my problem? I am a software guy
> and am not very good with hardware. Any advice or even google search words
> would be appreciated. Thanks for the help.

If the bitrate isn't too high, you could bitbang one of the UARTs. The
output would be the easiest. You can use a timer interrupt programmed
at the exact length of a bit, and keep a small state machine to
sequentially write the bits.

On Sat, 17 Nov 2007 05:51:12 -0600, "jonathan03" <jm_2003_2008@yahoo.com>
wrote:

>I am looking for an PIC with three UART ports if such a thing exists. I
>have two UART inputs and I want to output a single UART output. I've seen
>plenty of ICs with 2 UART ports, but I have yet to find one with three. I
>typically use microchip ICs, but I am open to any brand as long as it
>would do the trick and has a good C compiler. 

Atmel AVR ATMega 640/1280/2560 has four hardware UARTs. The programming
architecture is much more straigghtforward and C friendly than the PIC's
with their crippled architecture. A decent gcc port does exist, and there
are also some good commercial tools (Imagecraft, Codevision, IAR
(expensive!!!)).

Mit freundlichen Gr&#4294967295;&#4294967295;en

Frank-Christian Kr&#4294967295;gel

On Sat, 17 Nov 2007 05:51:12 -0600, "jonathan03" <jm_2003_2008@yahoo.com> wrote:

>I am looking for an PIC with three UART ports if such a thing exists. I
>have two UART inputs and I want to output a single UART output. I've seen
>plenty of ICs with 2 UART ports, but I have yet to find one with three. I
>typically use microchip ICs, but I am open to any brand as long as it
>would do the trick and has a good C compiler. 
>
>How would a situation like this be handled in modern electronics? I am a
>student and we typically would solve something like this with a MUX.
>However, 1) it seems pretty "primitve" for today's electronics - are these
>still used? and 2) I would like to use all three UART ports at the same
>time. 
>
>I was thinking of two ICs, but with only 2 UARTs that wouldn't solve the
>problem. The only other idea I could come up with would be to have an IC
>to store the data from each UART input to a memory IC. A third IC would
>then read/write from the shared memory and output a single UART output.
>
>Is there anything simple that would solve my problem? I am a software guy
>and am not very good with hardware. Any advice or even google search words
>would be appreciated. Thanks for the help.
>

If the baudrate is sensible, and depending on other interrupt activity, a soft UART is easy enough,
especially for TX only.  Creative use of a timer compare output might also be possible if interrupt
jitter is a problem.


 . 

On Sat, 17 Nov 2007 05:51:12 -0600, "jonathan03"
<jm_2003_2008@yahoo.com> wrote:

>I am looking for an PIC with three UART ports if such a thing exists. I
>have two UART inputs and I want to output a single UART output. I've seen
>plenty of ICs with 2 UART ports, but I have yet to find one with three. I
>typically use microchip ICs, but I am open to any brand as long as it
>would do the trick and has a good C compiler. 

As I read this, you are saying that two of your serial signals are
receive-only, while the third is transmit-only.

Can you not use UART1 to receive one receive only signal and send the
transmit-only signal, and use UART2 to receive the second receive-only
signal?

On most UARTs that I've used, the transmit and receive sections are
independent, except for baud rate.


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Peter Bennett, VE7CEI  
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