Re: ARM7 with longevity of supply

Tom Lucas wrote:
"rickman" <gnuarm@xxxxxxxxx> wrote in message
Who am I to argue with your requirements, but you might reconsider the
need for an 8 bit bus. These days most I/O is done directly from the
MCU or if expansion is needed, using SPI or I2C. If you tell us what
you need on the other end of the 8 bit bus maybe we can help you see
how easy it is to use one of the serial interfaces.

This is an issue because adding a data and address bus to an MCU
greatly increases the pin count and package size and therefore cost.

You are right in what you say and realistically I could probably do away
with a lot of the latches and flip-flops that expect 8 bit busses
(probably into an FPGA). However, I am only intending to replace the
processor area of an existing and working design and don't want too much
upheaval. It's less than ideal I know but gettign management to move
away from 80188 will be hard enough without having to redo the rest of
the system.

If you are using latches and FFs, you likely can find ways to roll that
into the MCU if you think about it a bit.

Cypress has been talking to me about their planned ARM parts that will
have the PSOC peripherals. That will be an amazing combination, almost
as good as an MCU and a CPLD!


I also don't think you will
find 5 years to be a problem for a product lifetime since nearly all
the ARM MCUs are relatively new and in high demand.

I think a lot of the longevity depends on large (probably automotive)
manufacturers adopting the microcontroller in question.

I think you will find that most ARM makers are shipping plenty of parts
and you can expect the quantities to continue for many years. With
several big semiconductor players adopting the ARM as their primary MCU
to market, this has push the architecture to the forefront in a way
that will be even stronger than the 8051 MCU. The chips being made
today are very good with very low power and high degrees of efficiency
and robustness so they will still be in products for many years.
Certainly if you go with one of the two big players, Atmel and NXP, you
will be able to buy these chips for many years. I don't think they
need an automotive partner. In fact, the automotive market likely will
move on to newer chips since with their volumes a savings of just a few
cents justifies changing to a different part.


One observation, if you want lower power chips, Atmel and NXP
(Philips)
are about neck and neck with roughly half the power consumption of the
other vendors. These parts will actually run at lower power than many
8 bit cores when you run them at the same speed. This is due to the
smaller process geometries.

I have oodles of power available so that is one restriction I can be
free of.

Yes, some apps don't care about power consumption, but there can also
be power dissapation issues, but I expect you don't have that
limitation either. If you were using the old technology you mentioned,
you will find the new parts to be a lot more size efficient too.

.

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