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'[SX]: Dual UART Virtual Perioheral'
2000\12\26@075008 by Russell McMahon

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Has anyone used Ubicom's combined virtual peripheral example - 2 x UARTs and
IIC as supplied in a single example program.

I'm having a few problems which MAY be due to having hacked the code about
somewhat but maybe not.
Can anyone confirm that the code works OK as supplied.



regards,





     Russell McMahon
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2000\12\26@121912 by Dan Michaels

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Russell McMahon wrote:
>Has anyone used Ubicom's combined virtual peripheral example - 2 x UARTs and
>IIC as supplied in a single example program.
>
>I'm having a few problems which MAY be due to having hacked the code about
>somewhat but maybe not.
>Can anyone confirm that the code works OK as supplied.
>

Hi Russell, I have used the VP code a little. Can you describe
more fully what your problem "appears" to be.

best regards,
- Dan Michaels
Oricom Technologies
http://www.oricomtech.com
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2000\12\26@161524 by Russell McMahon

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>>Has anyone used Ubicom's combined virtual peripheral example - 2 x UARTs
and
>>IIC as supplied in a single example program.
>>Can anyone confirm that the code works OK as supplied.

>Hi Russell, I have used the VP code a little. Can you describe
>more fully what your problem "appears" to be.
>- Dan Michaels


I can describe exactly what the problem "is" :-) - the UART that I have
tried to use so far works fine on transmit but not on receive AND as I
understand the supplied code, it appears faulty! I'm still new to Scenix and
may be missing something but don't think so (of course :-) ).

In the 2 UART plus MM IIC code they use a single global variable
uart_rx_flag in flags.0  as the character received bit for ALL UARTS. Or
that's how I read the code. This would be bizarre as either UART will set or
reset this flag as if it is the only UART in action. While it is a trivial
matter for me to either use another bit in the global registers or to use a
flag bit in a bank which is unique to the currently active UART this is
disturbing as it suggests one of -

i    The code as supplied never worked and / or has not been tested
(properly)

ii    I am missing a major point about how it works

Hence my query whether anyone else has used this specific code and whether
it works. I believe I fully understand the principles involved but clearly
either I or Ubicom are wrong! Which seems most likely ? :-)

A possibility is that if you only use one UART channel then it works OK if
the other is idle and they have expanded code for a one UART peripheral and
missed the error and tested it using only one UART at a time. I had hoped to
just drop this code into place with changes for different port arrangements
(to fit my existing hardware) and get on with the task which will be using
the VPs - I don't really want to be debugging Ubicom's code which I assumed
would be working! There is the possibility that I have done something silly
with port changes but I have checked it carefully several times and it all
should be quite straight forward.



regards

           Russell McMahon

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2000\12\26@212655 by Dan Michaels

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Russell McMahon wrote:

>I can describe exactly what the problem "is" :-) - the UART that I have
>tried to use so far works fine on transmit but not on receive AND as I
>understand the supplied code, it appears faulty! I'm still new to Scenix and
>may be missing something but don't think so (of course :-) ).
>
>In the 2 UART plus MM IIC code they use a single global variable
>uart_rx_flag in flags.0  as the character received bit for ALL UARTS. Or
>that's how I read the code. This would be bizarre as either UART will set or
>reset this flag as if it is the only UART in action. While it is a trivial
>matter for me to either use another bit in the global registers or to use a
>flag bit in a bank which is unique to the currently active UART this is
>disturbing as it suggests one of -
>


Russell, I just checked the ubicom site and didn't see a VP
combining I2C and RS232. The older I2C peripheral required you
to shut down all the other VPs to run it. Maybe they have fixed
it - by interleaving into the other VPs - in the past year.

Also, I was not very happy with some of their older VPs. The
multichannel PWM was a disaster. We talked about it last spring
on piclist. And once you get several VPs going, things tend to
bog down. Personally, I like to run one thing at a time rather
than multiple things on the scenix, but then go like a bat out
of h*** [religious references bleeped out on piclist].

Re the RS232 VP, you will notice that it probably will not run
faster than 19200, as the divider values [loop counters] will
have non-integer values. Also, it really looks to me like the
accuracy of sampling diminishes greatly for higher baudrates.
The VPs sample the ports when the timer interrupts occur, and
these are not locked to the actual port pin changes.
So ..... makes me wonder.

You might also check how they do RAM bank switching in the VP
you are looking at. This is the real key to how the VPs work.
For multiple VPs of the same type, they have duplicate variables,
used in exactly the same manner, but located in different banks.

best regards,
- Dan Michaels
Oricom Technologies
http://www.oricomtech.com
==================================================================
"To every thing there is a season, and a time to every purpose..."
==================================================================

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2000\12\27@064837 by Andrew Kunz

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Hey, Russ, there are enough Mot and Mchip appnotes with bugs - it isn't just
Scenix.

Andy

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2000\12\27@232349 by Russell McMahon

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>Hey, Russ, there are enough Mot and Mchip appnotes with bugs - it isn't
just
>Scenix.
>Andy


True, but the Scenix "virtual peripherals" are meant to be an alternative to
having the same functions in silicon.
As such, if they are to be the "flagships" for their product one would hope
they would be a little more sorted out than typical app notes.

That said, my present problems could all be of my own making. Time will
tell.
Hope to get back to it in a day or so.


   Russell

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