| Author |
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Nicholas O. Lindan
Guest
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 Posted:
Tue Dec 14, 2004 9:31 pm Post subject:
Re: Could PIC handle this? |
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"Goran Larsson" <hoh@invalid.invalid> wrote
| Quote: | More likely it is intended to alert a driver when approaching an
automatic speed camera.
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They publish the locations?
In Germany they do seem to stay in the same position
for an awfully long time.
--
Nicholas O. Lindan, Cleveland, Ohio
Consulting Engineer: Electronics; Informatics; Photonics.
Remove spaces etc. to reply: n o lindan at net com dot com
psst.. want to buy an f-stop timer? nolindan.com/da/fstop/ |
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Hans-Bernhard Broeker
Guest
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| Posted:
Tue Dec 14, 2004 9:40 pm Post subject:
Re: Could PIC handle this? |
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Nicholas O. Lindan <see@sig.com> wrote:
| Quote: | "Goran Larsson" <hoh@invalid.invalid> wrote
More likely it is intended to alert a driver when approaching an
automatic speed camera.
They publish the locations?
|
Some legislations do, indeed. Typically not by way of GPS
coordinates, but that's easily fixed by a dedicated service provider.
| Quote: | In Germany they do seem to stay in the same position for an awfully
long time.
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That's because these things have to be vandal-proofed to an extent
that does makes them quite hard to move. Most of the time there's no
camera in them, though. I.e. they move the camera, but not the box.
--
Hans-Bernhard Broeker (broeker@physik.rwth-aachen.de)
Even if all the snow were burnt, ashes would remain. |
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Guest
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| Posted:
Tue Dec 14, 2004 9:57 pm Post subject:
Re: Could PIC handle this? |
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Theres thousands of fixed ones - thick metal concreted into ground, not
moveable. Then theres many mobile ones - in vans or handheld (hiding
behind bushes near speed limit change signs, etc), carriageway bridges.
They publish the locations by listing road name, although theres some
public GPS lists. |
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Rufus V. Smith
Guest
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| Posted:
Tue Dec 14, 2004 10:48 pm Post subject:
Re: Could PIC handle this? |
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"hamilton" <hamilton@deminsional.com> wrote in message
news:41be53ef$1_1@omega.dimensional.com...
| Quote: | David wrote:
Could a PIC handle interfacing via rs232 with a GPS unit, and
comparing the location against a list of ~5000 stored positions, and
alerting (LED/LCD) if any points are considered close enough (~1-2km,
using haversine formula, perhaps)?
I guess the points would have to be stored on a CF/MMC card. They
would be updated/changed time to time...
I would be hard pressed to believe that a PIC can do this.
The largest/fastest PIC can do floating point math in seconds.
5000 * 2 floating point calculations (lat/long) would require 10s on
thousands of seconds. ( 10,000 seconds / 3600/hr = 2.77 hours )
Let alone storage and retrieval of 5000 pairs (lat/long) numbers.
Searching an external flash memory device would take a long time as well.
There are many other low cost solutions that can better handle this
problem. If your are cheap and this in not on a schedule, sure have fun.
But, when do you want to see this done ? Not within a single semester !!
hamilton
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What is the distribution of the stored positions?
it's possible that the points can be sorted according to regions, then the
only calculations would be: In which region is the test point? Are any
points
in this or immediately adjacent regions close enough?
Rufus |
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Rufus V. Smith
Guest
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| Posted:
Tue Dec 14, 2004 11:01 pm Post subject:
Re: Could PIC handle this? |
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"Nicholas O. Lindan" <see@sig.com> wrote in message
news:U5wvd.3165$2J2.1870@newsread2.news.atl.earthlink.net...
| Quote: |
The charm of using a PIC is the perverse satisfaction of getting
something useful out of what is arguably the world's worst
processor.
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ROTFLMAO!
But don't underestimate the satisfaction!
Rufus
(I envision that quote on a t-shirt) |
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Guest
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| Posted:
Tue Dec 14, 2004 11:25 pm Post subject:
Re: Could PIC handle this? |
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~5000 over the entire UK. distribution varies a little, but not hugely.
indexing it by longitude is probably best. |
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Clint Sharp
Guest
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| Posted:
Wed Dec 15, 2004 2:28 am Post subject:
Re: Could PIC handle this? |
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In message <41be53ef$1_1@omega.dimensional.com>, hamilton
<hamilton@deminsional.com> writes
| Quote: | David wrote:
Could a PIC handle interfacing via rs232 with a GPS unit, and
comparing the location against a list of ~5000 stored positions, and
alerting (LED/LCD) if any points are considered close enough (~1-2km,
using haversine formula, perhaps)?
I guess the points would have to be stored on a CF/MMC card. They
would be updated/changed time to time...
I would be hard pressed to believe that a PIC can do this.
The largest/fastest PIC can do floating point math in seconds.
5000 * 2 floating point calculations (lat/long) would require 10s on
thousands of seconds. ( 10,000 seconds / 3600/hr = 2.77 hours )
Let alone storage and retrieval of 5000 pairs (lat/long) numbers.
Check out this month's EPE mag (uk) |
http://www.epemag.wimborne.co.uk
They published a device based on a cheapish GPS module with NMEA output
and a 16F873 that does exactly what the OP requires, they even explain
the math.
| Quote: |
Searching an external flash memory device would take a long time as well.
There are many other low cost solutions that can better handle this
problem. If your are cheap and this in not on a schedule, sure have fun.
But, when do you want to see this done ? Not within a single semester !!
hamilton
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--
Clint Sharp |
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Nicholas O. Lindan
Guest
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| Posted:
Wed Dec 15, 2004 4:33 am Post subject:
Re: Could PIC handle this? |
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"Clint Sharp" <clint@clintsmc.demon.co.uk> wrote
| Quote: | Check out this month's EPE mag (uk)
http://www.epemag.wimborne.co.uk
They published a device based on a cheapish GPS module with NMEA output
and a 16F873 that does exactly what the OP requires, they even explain
the math.
|
Ah, neat: you program it when you pass a camera and it beeps when you pass
that way again.
So it has to store information to the resolution of the GPS, but it
doesn't have to cover the world.
Still wouldn't have picked a PIC.
All the computer software ever written can be executed on a computer
with just one instruction ...
--
Nicholas O. Lindan, Cleveland, Ohio
Consulting Engineer: Electronics; Informatics; Photonics.
Remove spaces etc. to reply: n o lindan at net com dot com
psst.. want to buy an f-stop timer? nolindan.com/da/fstop/ |
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Mike Page
Guest
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| Posted:
Wed Dec 15, 2004 4:36 am Post subject:
Re: Could PIC handle this? |
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David wrote:
| Quote: | Could a PIC handle interfacing via rs232 with a GPS unit, and
comparing the location against a list of ~5000 stored positions, and
alerting (LED/LCD) if any points are considered close enough (~1-2km,
using haversine formula, perhaps)?
I guess the points would have to be stored on a CF/MMC card. They
would be updated/changed time to time...
|
PICs come pretty big now - up to 128K (18F7820). I have used the 18F452
and it's nicely capable - fast clocking, hardware multiply, sane stack
depth, good peripherals. The 128K parts are a lot bigger and a bit better.
That's not to say the PIC is the best beast for the job. I've been
mostly using MSP430 recently, but they stop at 60K. I suspect that
beyond this, ARM is the best choice. Certainly plenty of FLASH.
I also suspect that your distance algorithm is a small part of the code,
both time and space. I would identify the critical part as being the
database of 5000 locations. How much memory do you need? At 20 bytes
each (5 single precision floats), you should fit into a 128K part and
have plenty space for kerfuffle. Perhaps cheaper to use a low
temperature PIC and slap in a 24512 or three.
Regards,
Mike. |
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Mike Page
Guest
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| Posted:
Wed Dec 15, 2004 4:37 am Post subject:
Re: Could PIC handle this? |
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hamilton wrote:
| Quote: | David wrote:
Could a PIC handle interfacing via rs232 with a GPS unit, and
comparing the location against a list of ~5000 stored positions, and
alerting (LED/LCD) if any points are considered close enough (~1-2km,
using haversine formula, perhaps)?
I guess the points would have to be stored on a CF/MMC card. They
would be updated/changed time to time...
I would be hard pressed to believe that a PIC can do this.
The largest/fastest PIC can do floating point math in seconds.
hamilton
|
[raspberry sound] Today's PICs have hardware multiply and run at up to
40MHz. For 8 bitters, they're rather good. |
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Spehro Pefhany
Guest
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| Posted:
Wed Dec 15, 2004 4:40 am Post subject:
Re: Could PIC handle this? |
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On Tue, 14 Dec 2004 23:37:16 +0000, the renowned Mike Page
<brian@brian.com> wrote:
| Quote: | hamilton wrote:
David wrote:
Could a PIC handle interfacing via rs232 with a GPS unit, and
comparing the location against a list of ~5000 stored positions, and
alerting (LED/LCD) if any points are considered close enough (~1-2km,
using haversine formula, perhaps)?
I guess the points would have to be stored on a CF/MMC card. They
would be updated/changed time to time...
I would be hard pressed to believe that a PIC can do this.
The largest/fastest PIC can do floating point math in seconds.
hamilton
[raspberry sound] Today's PICs have hardware multiply and run at up to
40MHz. For 8 bitters, they're rather good.
|
Some of todays PICs (18x and 17x at least) have sissy 8 x 8 hardware
multiply. The MSP430 has a manly 16 x 16 hardware multiply, which is 4
times the work. Although technically a 16-bit micro, it competes
directly. Also, 40MHz is the oscillator frequency-- the minimum
instruction cycle is 100ns.
Best regards,
Spehro Pefhany
--
"it's the network..." "The Journey is the reward"
speff@interlog.com Info for manufacturers: http://www.trexon.com
Embedded software/hardware/analog Info for designers: http://www.speff.com |
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Noel Henson
Guest
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| Posted:
Wed Dec 15, 2004 4:40 am Post subject:
Re: Could PIC handle this? |
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Mike Page wrote:
| Quote: | David wrote:
Could a PIC handle interfacing via rs232 with a GPS unit, and
comparing the location against a list of ~5000 stored positions, and
alerting (LED/LCD) if any points are considered close enough (~1-2km,
using haversine formula, perhaps)?
I guess the points would have to be stored on a CF/MMC card. They
would be updated/changed time to time...
PICs come pretty big now - up to 128K (18F7820). I have used the 18F452
and it's nicely capable - fast clocking, hardware multiply, sane stack
depth, good peripherals. The 128K parts are a lot bigger and a bit better.
That's not to say the PIC is the best beast for the job. I've been
mostly using MSP430 recently, but they stop at 60K. I suspect that
beyond this, ARM is the best choice. Certainly plenty of FLASH.
I also suspect that your distance algorithm is a small part of the code,
both time and space. I would identify the critical part as being the
database of 5000 locations. How much memory do you need? At 20 bytes
each (5 single precision floats), you should fit into a 128K part and
have plenty space for kerfuffle. Perhaps cheaper to use a low
temperature PIC and slap in a 24512 or three.
Regards,
Mike.
|
I think you could offload some of the redundant math to database creation
time. If you drop the idea of floats and went with scaled integers, you
could speed things up and save a great deal of space.
Scale the GPS into binary integers. There are 360 degrees of longitude,
each with 60 minutes and 4 places of fractional minutes. So 360 * 60
* 10,000 = 216e6 or a little less than 2^28 or 28 bits. Latitude would be
27 bits. This would speed up the math considerably. The only *conversion*
needed would be the GPS data into the binary format. Each point would be
8 bytes with no loss of resolution.
As I mentioned before, you could really speed up 'homing-in' on the closest
location by simply taking the sum of the differences of lon and lat. No
multiply would be needed. You could then take the time to perform 64-bit
multiplies on the closest 5 or 10 to select the true, closest item.
BTW, the sum of the differences technique is really pretty efficient. The
worst case error occurs when the points are at 45 degrees from each other.
Even then, it's still really close.
Noel |
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Paul Keinanen
Guest
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| Posted:
Wed Dec 15, 2004 11:57 am Post subject:
Re: Could PIC handle this? |
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On Tue, 14 Dec 2004 21:58:18 -0500, Spehro Pefhany
<speffSNIP@interlogDOTyou.knowwhat> wrote:
| Quote: | [raspberry sound] Today's PICs have hardware multiply and run at up to
40MHz. For 8 bitters, they're rather good.
Some of todays PICs (18x and 17x at least) have sissy 8 x 8 hardware
multiply. The MSP430 has a manly 16 x 16 hardware multiply, which is 4
times the work. Although technically a 16-bit micro, it competes
directly. Also, 40MHz is the oscillator frequency-- the minimum
instruction cycle is 100ns.
|
It is interesting to compare these clock frequencies and minimum cycle
times to the original MC6800 some 30 years ago running at 1 MHz and 1
us. Despite the huge improvement in silicon processing, the
performance of current 8 bitters is only modest.
While on wider processors, much of the performance increase is due to
using more and more transistors, the maximum clock frequency has also
grown several decades.
Thus, I would have expected that with current 130 nm line widths, the
performance would have been at least two decades better than with the
original 6800/8080/8085/Z80 processors, even with a similar number of
gates.
Are manufacturers afraid that fast 8 bitters would reduce the market
for 16/32 bit processors ?
Paul |
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Spehro Pefhany
Guest
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| Posted:
Wed Dec 15, 2004 12:14 pm Post subject:
Re: Could PIC handle this? |
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On Wed, 15 Dec 2004 08:57:17 +0200, the renowned Paul Keinanen
<keinanen@sci.fi> wrote:
| Quote: | On Tue, 14 Dec 2004 21:58:18 -0500, Spehro Pefhany
speffSNIP@interlogDOTyou.knowwhat> wrote:
[raspberry sound] Today's PICs have hardware multiply and run at up to
40MHz. For 8 bitters, they're rather good.
Some of todays PICs (18x and 17x at least) have sissy 8 x 8 hardware
multiply. The MSP430 has a manly 16 x 16 hardware multiply, which is 4
times the work. Although technically a 16-bit micro, it competes
directly. Also, 40MHz is the oscillator frequency-- the minimum
instruction cycle is 100ns.
It is interesting to compare these clock frequencies and minimum cycle
times to the original MC6800 some 30 years ago running at 1 MHz and 1
us. Despite the huge improvement in silicon processing, the
performance of current 8 bitters is only modest.
While on wider processors, much of the performance increase is due to
using more and more transistors, the maximum clock frequency has also
grown several decades.
Thus, I would have expected that with current 130 nm line widths, the
performance would have been at least two decades better than with the
original 6800/8080/8085/Z80 processors, even with a similar number of
gates.
Are manufacturers afraid that fast 8 bitters would reduce the market
for 16/32 bit processors ?
Paul
|
I've seen ads (from Western Design Center?) that show that a 65C02
core would run at several hundred MHz if manufactured in a modern
process. Maybe the market price per chip times the demand for such a
fast, but lean, processor won't support the up-front cost of such a
process.
Best regards,
Spehro Pefhany
--
"it's the network..." "The Journey is the reward"
speff@interlog.com Info for manufacturers: http://www.trexon.com
Embedded software/hardware/analog Info for designers: http://www.speff.com |
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Jonathan Kirwan
Guest
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| Posted:
Wed Dec 15, 2004 2:16 pm Post subject:
Re: Could PIC handle this? |
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On Wed, 15 Dec 2004 02:14:59 -0500, Spehro Pefhany
<speffSNIP@interlogDOTyou.knowwhat> wrote:
| Quote: | I've seen ads (from Western Design Center?) that show that a 65C02
core would run at several hundred MHz if manufactured in a modern
process. Maybe the market price per chip times the demand for such a
fast, but lean, processor won't support the up-front cost of such a
process.
|
The ever popular flash is generally slow and I/O pins generally don't need to be
near that fast, so the external interface is probably what makes this kind of
fast embedded 8-bit CPU in the center not so interesting. And if you add in
cache and inbound and outbound fifos, etc., it's not so interesting anymore to
have a 65C02 in the middle of all that. And there's the core voltage versus
what people would like for their applications, perhaps.
Jon |
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