Forums

UART x3

Started by jonathan03 November 17, 2007
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&#2013266172;&#2013265951;en Frank-Christian Kr&#2013266172;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. -- Peter Bennett, VE7CEI peterbb4 (at) interchange.ubc.ca new newsgroup users info : http://vancouver-webpages.com/nnq GPS and NMEA info: http://vancouver-webpages.com/peter Vancouver Power Squadron: http://vancouver.powersquadron.ca