Microcontroller expert around? - recommendation needed

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I hope this is the right place for such a question - sorry if I'm
breaking any protocol rules, but I really need some help.


I need ideas for what microcontroller to use for my application. I'm
going to be integrating an Inertial Measurement Unit (IMU) with a GPS
receiver using a Kalman Filter. This basically means I'll be adding up
measurements continually from the IMU (about 80 Hz) and when a GPS
measurement comes in (typically 1 Hz) I will be running all the
measurements through a Kalman Filter to provide me with error
estimates. The Kalman filter means lots of big matrix multiplications
(18x18) with floating point numbers (done once a second). I need at
least a 16-bit controller, maybe 32(?). This is going to be generating
position information real-time.


All my measurements are going to be digital already so I don't need
any D/A stuff. Flash memory (as much as possible) on-chip would be
great so I could store measurements. An easy way to communicate with a
PC or a PDA would be good. All this with as low a power as possible
with a development kit <$2500. Any ideas? HELP!


I've looked at the Renesas SuperH family, anyone used these? Thanks!

Re: Microcontroller expert around? - recommendation needed
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SuperH would be a good start, maybe an SH2+DSP.  Also, a possible fit lower
on the cost curve but with lower power, would be an H8S (some of these have
MACs), a Motorola M-CORE, or an Atmel or Phillips ARM processor.  As far as
how to communicate with a PDA, it depends on the PDA.  SDIO seems to me to
be congealing into a plurality, but developing a SDIO "peripheral" is a
major commitment.

Sometimes, a 32-bit timer with input capture winds up being a nice thing to
have with GPS designs.  These are rare, but they do exist -- look for parts
targeted toward automotive markets.

As far as cheap tools: keep an eye out for parts with a JTAG debugger, which
*usually* opens the door a bit for more variety of tools.  In my experience,
stick to the GNU C or C++ compiler.  Using proprietary tools is not only
expensive, but if you get into trouble (compiler or tool problems), then it
costs real money to get out of it.  GNU is not perfect, and it's IDE's arent
as nice, but the user base is huge and the output code is generally very
good.  Microcross is a good place to start for graphical GNU tools.  For an
ARM processor, for instance, you can easily have a GUI IDE, Compiler, JTAG
Emulator, and evaluation board for well under $2000.



Re: Microcontroller expert around? - recommendation needed
On Mon, 11 Aug 2003 18:33:21 -0400, "Ian McBride"

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If you're using the SH-X or H8S, then you might want to look at the
Hitachi C/C++ Compiler. On a H8 platform, our analysis has shown that
the Hitachi compiler produces 25% more compact code when compared to
GNU. Also we found the Hitachi support to be excellent (and free for
us). Although the GNU toolset is basically free, the maintenance
contracts usually amount to cost more than the commercial C compilers
(which kinda negates the motivation to use the GNU toolset). Of course
there are the various support forums, but I found that their
helpfulness is not consistent.

So if you don't need support & able to tolerate the inefficiencies of
the generated code, then GNU is more than adequate (for Hitachi micros
anyway). For Win32 development environments, I would recommend the one
from Kpit.

Ken.

+====================================+
I hate junk email. Please direct any
genuine email to: kenlee at hotpop.com

Re: Microcontroller expert around? - recommendation needed
           snipped-for-privacy@aol.com "Jonathan Neu" writes:

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Perfect place.
 
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Cheapish development cards for the Hitachi H8 family are available
from Triangle Digital Services (TDS2020 card) and Microprocessor
Engineering (Powerboard). Both systems come with a wealth of Forth
tools and make good use of the on-chip resources. Their websites are
linked from the bottom of my Forth page. I have used products from
bith companies and their back-up service is excellent.

--
********************************************************************
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Re: Microcontroller expert around? - recommendation needed
You might consider the TI TMS320VC5470 or OMAP series.  They combine an ARM7
or ARM9 MCU with a DSP on the same chip.  The math is a snap for the DSP and
then you have the ARM to do the rest.  Has flash, ram, etc.  Developer kits
available in the $1500 range (I think) the IDE is more, but you may find it
bundled with the developer kit.

--
Scott Nowell
ExoTech R&D, Inc.
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Re: Microcontroller expert around? - recommendation needed

"steve at fivetrees" wrote...
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http://www.eu.renesas.com/news/press_releases/01april03_eu.html

which starts like:

"London, 1 April, 2003 : Renesas Technology Europe Limited was launched
today marking the beginning of the joint venture between Hitachi, Ltd and
Mitsubishi Electronics Corporation. The new company will focus on the design
and manufacture of highly integrated semiconductor system solutions for the
mobile, network, and automotive industries, digital home electronics and
industrial markets. Key products will be: microcontrollers, including smart
card ICs; flash memory technologies; and mixed signal devices. These are all
areas where the joint company is already a leading supplier.
 ...   "


Regards,
Arie de Muynck




Re: Microcontroller expert around? - recommendation needed
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totally

Thanks for that. I'm reassured ;).

Steve
http://www.sfdesign.co.uk
http://www.fivetrees.com



Re: Microcontroller expert around? - recommendation needed
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simpler

It smells like a poor man's cruise missile, done by someone who doesn't know
all that much about Kalman filtering.

18 states:  I'm guessing, but I'd say he probably has:

  X Y Z position
  X Y Z velocity
  X Y Z acceleration
  Yaw Pitch Roll position
  Yaw Pitch Roll velocity
  Yaw Pitch Roll acceleration

80 Hz IMU updates, with Z-axis position/velocity/acceleration, make it a
flying machine as opposed to a ground vehicle, surface boat, or submarine.
At that, it is a flying machine with some pretty ugly dynamics, if he needs
80 Hz control information.  GPS as opposed to a local beacon system make it
a vehicle with a fairly long range and a relatively noncritical positioning
requirement (because of GPS position errors).

Oh, and GPS also rules out a spacecraft.  The velocities involved in space
travel, even orbital travel, are too high for GPS navigation.

Put them all together, and "cruise missile" is what comes out.



Re: Microcontroller expert around? - recommendation needed
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Nothing that sinister, John.  Just a cheap, commercially available
MEMS IMU integrated with a GPS receiver to see what kind of low-cost,
small-size, low-power performance I can get.  Its best use would be as
a component in a larger system.  This is just masters' level thesis
work...

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Probably not XYZ acceleration, and almost certainly not attitude
velocity or acceleration.  The rest of the states would be system
errors such as those I mentioned previously.

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The IMU update rate is largely out of my control because it's a cheap
commercial-off-the-shelf IMU.  Of the three IMUs I hope to test with,
only one is over $2000.

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GPS because it's cheap, easy, and doesn't limit where the system can
function.

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I'm not expert enough to dispute you on the main point, but I do know
that the shuttle gets excellent GPS performance because of the lack of
atmospheric error (granted, the shuttle is in LEO).

Re: Microcontroller expert around? - recommendation needed
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If you're referring to the size of the matrices, it's because it's a
navigation filter.  Right now it looks like I'll be doing an
error-state implementation of a GPS-aided INS (although details could
change).  That means anywhere from 12-?? states depending on how
detailed I need to get to achieve good performance.  Now some of the
matrices may be sparsely populated, but they need to be this big
simply because of the sheer number of states I have to keep track of
(3 position states, 3 velocity states, 3 attitude states, gyro drifts,
accelerometer biases, GPS clock error and pseudorange error, etc.).

Re: Microcontroller expert around? - recommendation needed
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simpler

No, I was referring to the use of matrices at all. I repeat: what is the
objective? Alternatively, what is the nature of the noise that you seek to
filter out?

(It's a slightly trick question. GPS has artefacts that can be caught with a
smart filter, and others that can only be caught by longterm sampling of the
same position i.e. without movement.)

Steve
http://www.sfdesign.co.uk
http://www.fivetrees.com



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