recommendation for 8 port rs232 embedded micro

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We are looking for recommendations for an 8 port rs232 embedded micro.
The CPU processing requirement is minimal.

Any suggestions?



Re: recommendation for 8 port rs232 embedded micro

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which baud rate ?

Kasper



Re: recommendation for 8 port rs232 embedded micro

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4800 baud

Re: recommendation for 8 port rs232 embedded micro
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With a bit of thought and care, that should be possible to do in
software on a small micro, especially if the environment is not too
noisy (so that you can use 4 times oversampling instead of 8 or 16).

Re: recommendation for 8 port rs232 embedded micro
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Aha, smells like an NMEA multiplexer :-)

Meindert
www.shipmodul.com



Re: recommendation for 8 port rs232 embedded micro

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You guessed it.

Re: recommendation for 8 port rs232 embedded micro
On Mon, 06 Jun 2005 09:34:39 +0200, David Brown

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What you need is a reasonably fast micro, and do it all in software.
At that slow a baud rate (x8), you could easily do it all in a Ubicom
ip2k, running at a leisurely 120 Mips. It would be a one chip
solution, unless you need to satisfy the +-12 volt rs232 spec, then
you would need external level shifters.



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Re: recommendation for 8 port rs232 embedded micro
Now if you had said 4800 baud right from the start that would of helped
a little bit (vs 115,200 baud). I say a little bit because we (the NG)
still don't know if that is 8 simultaneous full-duplex channels or a
rather mundane 1 of 8 channel mux etc. Yes, based upon the incomplete
information an ARM could handle this ok (slow GPIO is not that much of
an issue here).

*Peter*

BTW, I would love to help more but even my non-technical customers give
me more information than this to go on.

Want specific answers? Supply specific information.


Anchor wrote:
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Re: recommendation for 8 port rs232 embedded micro
On Sat, 04 Jun 2005 19:57:05 -0400, Anchor

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What about the AVR FPSLC ? You can add extra UARTs using the on-chip
FPGA.

Regards
   Anton Erasmus


Re: recommendation for 8 port rs232 embedded micro
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Do the need to be all operational simultaneously?

Depending on the variety of Cypress PSoC you can have up to 4 UART
simultaneously, but you can dynamically switch I/O pins so you increas
that number to many more if they are not operating simultaneously. If you
application does require that all operate simultaneously, if you ar
working 1/2 duplex and you can arrange some kind of synchronization, it i
possible to split the UARTs into transmitters and receivers and use the pi
switching technique as well.

Of course the RS232 will have to be external.

        
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Re: recommendation for 8 port rs232 embedded micro
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I have an 8MHz AVR running 4 receiving software uarts and 2 transmitting
software uarts. So take a 60MHz ARM thingy and you'll be fine for 8
channels.

Meindert



Re: recommendation for 8 port rs232 embedded micro
On Sun, 5 Jun 2005 17:01:56 +0200, "Meindert Sprang"

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Be careful with that assumption. AFAIK the AVR can actually toggle
pins faster than the Philips LPC2XXX ARM MCU. (If that was the ARM you
were referrring too). The speed at which a MCU can toggle an I/O pin
has often absolutely nothing to do with the speed at which the same
MCU can do other processing.

Regards
  Anton Erasmus

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Re: recommendation for 8 port rs232 embedded micro
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But the code needed for th uart takes much much more time to execute. That
will be the bottleneck IMO.

Meindert



Re: recommendation for 8 port rs232 embedded micro
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I designed a multiport comms hub a few years ago which had a mid-range PIC
interfaced to a number of '2313 AVRs used as UARTs via SPI. I had to use
software SPI on the '2313s; nowadays I'd use the Tiny2313 which has hardware
SPI.

Leon



Re: recommendation for 8 port rs232 embedded micro
Have a look at the Cypress PSoC Microcontroller. I don't know how many UARTs
you can fit into the current devices - but hey're real
UARTs - not software ones .....

Richard.


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hardware



Re: recommendation for 8 port rs232 embedded micro
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How about a Cypress PSoC?  If you get one of the larger ones with lots
of I/O you should be able to instantiate many UART's.  I haven't checked
if there is one that can handle 8 but I think the larger ones might.
There will certainly be enough I/O.  If there are devices that have
enough digital blocks for the 8 UART's you'll be set for a one chip
solution (for the logic) and a few multi-channel RS232 transceivers.

Cheers,

James.


Re: recommendation for 8 port rs232 embedded micro

 
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You say minimal - what sort of thing would the CPU be doing?

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Re: recommendation for 8 port rs232 embedded micro

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Slicing and dicing NMEA data from several simultaneous talkers, repeating
the NMEA sentences in an ordered fashion eliminating the collisions.

Re: recommendation for 8 port rs232 embedded micro
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If there is no micro that has 8 UARTs operating simultaneously and yo
have no desire to create 8 software UARTs, why not try a low end micro an
an octal UART, for example

http://www.exar.com/product.php?ProdNumber=XR16L788&areaID=3
http://www.semiconductors.philips.com/pip/SCC2698B.html
http://www.semiconductors.philips.com/pip/SC28L198.html




        
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Re: recommendation for 8 port rs232 embedded micro
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For the price of one of those octal uarts you can buy 16 ATtinys playing
UART, and connect them with SPI.

Meindert



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