Forums

5509A in either HPI or EMIF mode

Started by ludovic44fr February 15, 2005


Hi everyone,

We are currently upgrading our product, going from 5410A to 5509A.

I do need to use the EMIF to load my code from flash, and i also need
to use the HPI to communicate with the Host.

The only problem, is that these 2 ports (EMIF and HPI) are
multiplexed, on the 5509A, in one port called "Parallel port", and
that only one can be selected at reset.

TI states in its Peripheral User Guide that it can be reconfigured by
soft by writing in the EBSR (External Bus Selection Register). OK but...

Unfortunately, in the last revision of the 5509A datasheet, they also
state : "Dynamic switching of the parallel port, once configured, is
not recommended." Which means don't do it !!!

Having contacted the EPIC, i got this reply from them :

" You are right, on the C5509A, unlike on the C5409A, you need to make a
choice at reset between either using the EHPI or the EMIF.

There are 2 ways around using a host interface:
o either reset the DSP (reset pin) each time you need to make HPI
access.
This is very drastic but is the only recommended way in order to the
HPI to
responds as per the data sheet operating conditions.
o implement a protocol to use the EMIF as host interface.
This means the DSP would have to react to an external event either by:
o an interrupt, and have an ISR read the host information
o by pulling a value on an external GPIO
"

So in definitve, it's seems to me that if you are booting your code
from flash, you just loose the HPI capability of the DSP !?

As anyone any experience on this DSP and faced the same probem ?
Or am I reduce to implement my own HPI interface ...?

Thanks for your replies.
Ludovic


Ludovic-

You may find the answer is: use the C5502. After much study and tradeoff analysis,
that's what we did.

With C5502, you keep 32-bit EMIF and 8-bit HPI simultaneous. The cache on the C5502
and 300 MHz clock rate make up at least partially for lack of additional onchip
SRAM. The only real loss was the USB, but with C5509A you need a USB transceiver
anyway, and you can find tiny USB peripheral chips that include both SIE and
transceiver and either give you a UART-type interface or hook up as async EMIF.

The end result is no loss in board space, and a net decrease in board cost. Plus you
get a UART out of the deal and you still have I2C.

I guess if A/D converter, MMBus and other C5509A unique peripheral features are
making a big difference, then my analysis is off base.

-Jeff ludovic44fr wrote:
>
> Hi everyone,
>
> We are currently upgrading our product, going from 5410A to 5509A.
>
> I do need to use the EMIF to load my code from flash, and i also need
> to use the HPI to communicate with the Host.
>
> The only problem, is that these 2 ports (EMIF and HPI) are
> multiplexed, on the 5509A, in one port called "Parallel port", and
> that only one can be selected at reset.
>
> TI states in its Peripheral User Guide that it can be reconfigured by
> soft by writing in the EBSR (External Bus Selection Register). OK but...
>
> Unfortunately, in the last revision of the 5509A datasheet, they also
> state : "Dynamic switching of the parallel port, once configured, is
> not recommended." Which means don't do it !!!
>
> Having contacted the EPIC, i got this reply from them :
>
> " You are right, on the C5509A, unlike on the C5409A, you need to make a
> choice at reset between either using the EHPI or the EMIF.
>
> There are 2 ways around using a host interface:
> o either reset the DSP (reset pin) each time you need to make HPI
> access.
> This is very drastic but is the only recommended way in order to the
> HPI to
> responds as per the data sheet operating conditions.
> o implement a protocol to use the EMIF as host interface.
> This means the DSP would have to react to an external event either by:
> o an interrupt, and have an ISR read the host information
> o by pulling a value on an external GPIO
> "
>
> So in definitve, it's seems to me that if you are booting your code
> from flash, you just loose the HPI capability of the DSP !?
>
> As anyone any experience on this DSP and faced the same probem ?
> Or am I reduce to implement my own HPI interface ...?
>
> Thanks for your replies.
> Ludovic





--- In , "ludovic44fr" <ludovic.tramart@t...>
wrote:
>
>
> Hi everyone,
>
> We are currently upgrading our product, going from 5410A to 5509A.
>
> I do need to use the EMIF to load my code from flash, and i also
need
> to use the HPI to communicate with the Host.
>
> The only problem, is that these 2 ports (EMIF and HPI) are
> multiplexed, on the 5509A, in one port called "Parallel port", and
> that only one can be selected at reset.

Is the boot flash the only thing you were using the EMIF for? How
about booting from a SPI EEPROM instead? Another way would be to have
your host processor load the code via the HPI. If you've got room for
the code in your host's flash, that could save you a part.

David L. Rick
Hach Company