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GPS Units = Show road steepness?



 
 
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  #91  
Old March 15th 19, 01:11 PM posted to rec.bicycles.tech
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Default GPS Units = Show road steepness?

On Thursday, March 14, 2019 at 7:47:56 PM UTC-7, Mike A Schwab wrote:
On Thursday, March 14, 2019 at 10:17:21 AM UTC-5, Radey Shouman wrote:
Mike A Schwab writes:

On Wednesday, March 13, 2019 at 10:52:57 AM UTC-5, Radey Shouman wrote:
Mike A Schwab writes:

Here is a great article by Sheldon Brown showing how bicycle
cyclometers work. When bladed spokes came out, some units would
register twice the distance at slow speed up to 6 mph 10 kph, so it
can give you an idea of how fast it can register the magnetic field
closing and opening a reed switch in the pickup.

https://www.sheldonbrown.com/cyclecomputer-magnet.html

That does seem to show that, at least at slow speeds, on a high-end
computer, every reed switch pulse is used to compute a new speed. It's
not clear whether the computer fails to register a double pulse at
higher speeds, or that the internal algorithm changes. Either one is
possible.

Here is a bicycle handlebar bubble inclineometer if you are still
interested.
https://www.amazon.com/Sun-Company-C.../dp/B06XCMXRVP

--

OK. 10,000 meters per hour / 3600 seconds per hour gives 2.78 meters
per second. A 700c road tire is about 2.1 meters per revolution, so
1.3 revolution per second. The width of the gap between the magnetic
field has to be under 10 MM 0.010 M so 0.013 second minimum time
without magnetic field to detect gap between the two sides of the
magnetic field. So 100 hz detect frequency???


When I threw out 100 Hz I was imagining a solution based on software
interrupt handling -- that was a WAG, and I doubt that's actually what
is used. I would pick a micro with hardware encoder input that can be
configured to count step and direction, so everything happens in
hardware. 13 ms is a long time in that case.


--


Well, actually the reed switch is effectively a relay. Takes 1/100 of a second to close in the gap between the sides of the magnet. Computer could be sampling much more often. And a faster speed doesn't give the reed switch enough time to close.


I would have to think about that for a minute. That appears to be a good idea. Microswitches are a quality control problem though I think that they would actuate better than 10 msec. In any care it wouldn't matter since 100 kph would be a maximum rotational period of, what, 72 msec.

Inductive switching would be inherently less likely to have quality control problems but it would also make the input circuitry more difficult to control since the rapid crossing of the coil by a magnet at high speed would generate a higher voltage signal and likewise lower speeds very little. So you complicate the input circuitry either by amplifying the lower speed inputs and then using a Zener or something to regulate the higher or visa versa. The problem here is that you're messing around with potentially destructive voltages around low voltage circuitry.

I would say that it's probably a tossup since microswitches are very old technology and manufacturing is stable.
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  #92  
Old March 15th 19, 01:25 PM posted to rec.bicycles.tech
Frank Krygowski[_2_]
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Default GPS Units = Show road steepness?

On Friday, March 15, 2019 at 5:26:16 AM UTC-4, Rolf Mantel wrote:
Am 15.03.2019 um 03:27 schrieb John B. Slocomb:
Hey! Somebody got an employee of the month award, complete with $10
Starbucks gift card for saving that $0.05.

A chap I worked with had worked for Ford Motorcar Co. and had gotten a
cash award for showing how they could install 2 fewer sheet metal
screws in the firewall of a Ford motorcar.


The cost of those 2 screws is not their material value but the time of
the worker who has to screw them in.


And/or the slight slowdown of production time required
to put them in.

- Frank Krygowski
  #93  
Old March 15th 19, 01:28 PM posted to rec.bicycles.tech
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Default GPS Units = Show road steepness?

On Thursday, March 14, 2019 at 9:01:22 PM UTC-7, James wrote:
On 15/3/19 1:47 pm, Mike A Schwab wrote:


Well, actually the reed switch is effectively a relay. Takes 1/100 of
a second to close in the gap between the sides of the magnet.
Computer could be sampling much more often. And a faster speed
doesn't give the reed switch enough time to close.


Why does it need to be "sampling"?

The switch may be connected to a digital input that generates an
interrupt upon a rising (or falling) edge, for example. The ISR could
then read and reset a timer/counter since the last rising edge was
detected. A counter can keep track of distance travelled.


At 60 m/s (in excess of 200km/h), with a nominal 2m circumference, the
wheel spins 30 revs per second. A 100 uS timer period would capture the
speed of 1 rev with better than 1% accuracy at this speed.

So long as it could count to 100,000 (not impossible for a 4 bit
computer to handle roll over), it could also measure speed at 1km/h.

The screen could be updated with the latest distance or filtered speed
every second or when it has changed.

--
JS


James - If, as Frank says, they are using a 4 bit uP, that counter is a whole lot easier said than done. As I pointed out the counter has to be at least 20 bits and more likely 24. Small, cheap uP are that way for a reason - they have very little support circuitry. Dealing with large numbers is not their strong point.

Also Zen's idea that you can make enough of ANY bicycle component to qualify it for custom fabrication is WAY over the top. I wonder if he knows what it cost to manufacture custom chips that will be outdated next year because someone gives their's another feature. Speed averaging for display isn't the world's easiest problem and they are doing that in a continuous update.

Since the altitude problem requires two inputs minimum to an ADC there is no possibility of making a custom chip. And he doesn't seem to know what a gate array is or what it does.
  #94  
Old March 15th 19, 01:32 PM posted to rec.bicycles.tech
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Posts: 1,260
Default GPS Units = Show road steepness?

On Friday, March 15, 2019 at 2:26:16 AM UTC-7, Rolf Mantel wrote:
Am 15.03.2019 um 03:27 schrieb John B. Slocomb:
Hey! Somebody got an employee of the month award, complete with $10
Starbucks gift card for saving that $0.05.

A chap I worked with had worked for Ford Motorcar Co. and had gotten a
cash award for showing how they could install 2 fewer sheet metal
screws in the firewall of a Ford motorcar.


The cost of those 2 screws is not their material value but the time of
the worker who has to screw them in.


Exactly - a manufacturing engineer who has analyzed the Tesla says that a single fender panel has 14 operations to install it whereas a Ford would have about 7. And that seems funny to me since my Ford has access panels inside of it to get to the Windshield Washer reservoir for servicing.
  #95  
Old March 15th 19, 01:34 PM posted to rec.bicycles.tech
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Default GPS Units = Show road steepness?

On Friday, March 15, 2019 at 4:52:15 AM UTC-7, Theodore Heise wrote:
On Thu, 14 Mar 2019 06:09:43 -0700 (PDT),
Zen Cycle wrote:
On Wednesday, March 13, 2019 at 5:36:37 PM UTC-4, Radey Shouman wrote:


The thing about an RTC that is likely to make users unhappy is
having to adjust the clock time.


I find this aggravating. I know this probably isn't a legit
RTC, but the clock in my car loses a minute per month (no, I'm
not exaggerating)


Seems I've read somewhere (or heard) that accuracy of some car
clocks can be affected if the voltage isn't close enough to the
expected 12 volts. I can't find much on the web (in a quick
search) to support that possibility, so it may well be wrong.

--
Ted Heise West Lafayette, IN, USA


Old time analog clocks used to be that way. Digital clocks aren't since they use a crystal timer.
  #96  
Old March 15th 19, 01:55 PM posted to rec.bicycles.tech
AMuzi
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Posts: 10,351
Default GPS Units = Show road steepness?

On 3/14/2019 9:27 PM, John B. Slocomb wrote:
On Fri, 15 Mar 2019 01:58:37 +0000 (UTC), Ralph Barone
wrote:

Radey Shouman wrote:
Zen Cycle writes:

I find this aggravating. I know this probably isn't a legit RTC, but
the clock in my car loses a minute per month (no, I'm not
exaggerating), yet I have a ten year old MP3 player I use when working
out that I've never had to rest the clock (I paid $40 for it in
2009). My car is a 2010 element, and it's had this problem since it
was new. I understand from reviewing several internet forums that this
is sort of a known issue, and the dealer said all hondas from that
period that _don't_ have factory navigation systems have this
problem. I understand that saving a few pennies per car means a lot on
the overall cost of the product, but really?

Somebody saved $0.05 on parts. Not always a win.


Hey! Somebody got an employee of the month award, complete with $10
Starbucks gift card for saving that $0.05.


A chap I worked with had worked for Ford Motorcar Co. and had gotten a
cash award for showing how they could install 2 fewer sheet metal
screws in the firewall of a Ford motorcar.

--
Cheers,
John B.



In my 1965 all the dash controls are diecast zinc. On a 1966
they're chromoplastic. I always imagined that somebody
retired on that change.

--
Andrew Muzi
www.yellowjersey.org/
Open every day since 1 April, 1971


  #97  
Old March 15th 19, 04:42 PM posted to rec.bicycles.tech
David Scheidt
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Posts: 1,310
Default GPS Units = Show road steepness?

Theodore Heise wrote:
:On Thu, 14 Mar 2019 06:09:43 -0700 (PDT),
: Zen Cycle wrote:
: On Wednesday, March 13, 2019 at 5:36:37 PM UTC-4, Radey Shouman wrote:

: The thing about an RTC that is likely to make users unhappy is
: having to adjust the clock time.
:
: I find this aggravating. I know this probably isn't a legit
: RTC, but the clock in my car loses a minute per month (no, I'm
: not exaggerating)

:Seems I've read somewhere (or heard) that accuracy of some car
:clocks can be affected if the voltage isn't close enough to the
:expected 12 volts. I can't find much on the web (in a quick
:search) to support that possibility, so it may well be wrong.

Quartz clocks slow down when voltage drops too low. I would expect a
car clock to be voltage regulated enoughto not matter, as automobile
voltages range from 11 to 15 volts, in normal operation. Stability
under temperature variation is a big issue with quartz clocks, I
wonder if that's the short cut they toook. It's one of the reasons
mecanical clocks (with an elctric motor to wind them....) lasted until
the 80s in cars.

--
sig 99
  #98  
Old March 15th 19, 06:24 PM posted to rec.bicycles.tech
Radey Shouman
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Posts: 1,251
Default GPS Units = Show road steepness?

John B. Slocomb writes:

On Fri, 15 Mar 2019 01:58:37 +0000 (UTC), Ralph Barone
wrote:

Radey Shouman wrote:
Zen Cycle writes:

I find this aggravating. I know this probably isn't a legit RTC, but
the clock in my car loses a minute per month (no, I'm not
exaggerating), yet I have a ten year old MP3 player I use when working
out that I've never had to rest the clock (I paid $40 for it in
2009). My car is a 2010 element, and it's had this problem since it
was new. I understand from reviewing several internet forums that this
is sort of a known issue, and the dealer said all hondas from that
period that _don't_ have factory navigation systems have this
problem. I understand that saving a few pennies per car means a lot on
the overall cost of the product, but really?

Somebody saved $0.05 on parts. Not always a win.


Hey! Somebody got an employee of the month award, complete with $10
Starbucks gift card for saving that $0.05.


A chap I worked with had worked for Ford Motorcar Co. and had gotten a
cash award for showing how they could install 2 fewer sheet metal
screws in the firewall of a Ford motorcar.


Years ago, while an undergrad, I worked summers at a US govt
installation that shall remain nameless. They had an employee
suggestion program, which offered cash prizes.

This was during the second 1970s oil price shock, and saving energy was
big. One of my cow-orkers submitted a suggestion to remove all the
olive drab paint from the windows of the building where he worked, so
God's free sunlight could reduce the need for electricity. He got a
cash prize.

Several months later, our hero submitted a suggestion noting that
classified material was handled in the building, and someone without the
appropriate clearance might look in through the windows. He got a cash
prize.
  #99  
Old March 15th 19, 06:29 PM posted to rec.bicycles.tech
Radey Shouman
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Posts: 1,251
Default GPS Units = Show road steepness?

Frank Krygowski writes:

On 3/14/2019 3:59 PM, Zen Cycle wrote:
On Thursday, March 14, 2019 at 1:37:04 PM UTC-4, Radey Shouman wrote:
Zen Cycle writes:

On Wednesday, March 13, 2019 at 5:36:37 PM UTC-4, Radey Shouman wrote:
Zen Cycle writes:


The simple count method I listed would easily be able to update
current speed with a one-second display refresh rate.

We'll just have to disagree, then. Have you written any embedded
software at all?

Not using a microcontroller/processor as the target. I'm not a
software engineer - quite franlkly it bores the **** out of me.

And yet you are entertained by arguing about it. Odd.


I didn't write that I don't have any experience at it - I've been
involved in code reviews at my various positions for over 30
years. In my current position, one of my responsibilities is
maintaining and updating Labwindows CVI (also c-based) for our
manufacturing ATE, and even then I've been caught sleeping with my
fingers on the keyboard. IF I had to write those whole 10K+ lines of
code from scratch.....ugh.


I'm a
hardware engineer. I've written VHDL with Altera and Xilinx targets
for combinatorial boolean blocks and counter/timer functions. It's all
C-based, so not too far removed from 'real' software (our software
team used to like to bust our chops about 'real' SW vs FW/VHDL). Some
were implemented in manufacturing as programmed FPGAs, but a few were
prototypes with the intention of using the resultant structure to
develop an ASIC. This was part of a telecom optical network testing
tool for commissioning optical network switching hubs (aka 'central
office') when I was with a telecom test group at HP in the early
'90s. We specialized in asychronous transfer mode (ATM) protocol error
injection to test the ability of the networks to both detect the
errors and correct them. Our senior scientist got a patent for a
segmentation and reassembly chipset that used the 'leaky bucket'
algorithm. Those were fun times.....

That explains the idea of an ASIC, and the idea that it's simple to count
clocks between two signal edges.

Designing for hardware is much different from software.


You don't say...

In hardware,
everything happens at once, which can bite you in the ass.


Well, that's the first I've heard that concurrent task handling and
speed are a bad thing, though I do remember having to write
synchronizers into the combinatorial sections because the
propagation delay took us a bit by surprise. This wasn't exactly a
bad problem to have.

In software,
at least with only one core, you can't do two things at once no matter
how convenient it would be. In hardware, if you have the gates you can
dream up completely new ways of capturing inputs. In software, you use
what the hardware gives you, sometimes ingenuity pays off and you can
use it for an unintended use, but that's not the way to bet.

Consumer electronics is also much different from industrial test
equipment. In consumer software the three most important things a

1. BOM cost
2. BOM cost
3. Schedule, it has to ship in time for Christmas, no matter what.


Right, that's why earlier I wrote "To invest in that kind of
software development [quantization error correction] for a bike
computer simply isn't cost effective, they'll never get the NRE
return. For us, a simple counter with an ALU is more than enough".
You're suggesting an ASIC won't give the return on investment -
which can be true - and I'm suggesting quantization error correction
won't give the return.


That's why I don't believe an ASIC is used in bike computers, sure you
could build in a bunch of neat features, but the NRE for a new ASIC,
while it has come down a lot, is still well north of $1M.



Nah....from
https://electronics.stackexchange.co...stom-asic-made

*********
FPGA Conversions: ........

Pros: Low NRE (US$35k is about the lowest). Low minimum quantities
(10k units/year).

Cons: High per-chip costs-- maybe 50% the cost of an FPGA. Low
performance, relative to the other solutions.
**************

Making that
back on a product with a wholesale price of a few dollars is just not
easy. Also note #3, picking parts that are available now is the way to
go.


Considering that a cheesy 8 bit Microchip ucontroller is about $5 in
the 100's it's likely you're right - most non-gps bike computers are
probably ucontroller based.


For what it's worth, Cateye says its units use a "4 bit one-chip
microcomputer (Crystal controlled oscillator)"
See
https://www.cateye.com/files/manual_..._HP_ENG_v1.pdf


Note that 4 bits is just enough to encode one decimal digit. I'll bet
most of the computation is done in binary coded decimal, as it is for
handheld calculators.
  #100  
Old March 15th 19, 09:14 PM posted to rec.bicycles.tech
Zen Cycle
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Posts: 91
Default GPS Units = Show road steepness?

On Thursday, March 14, 2019 at 8:38:54 PM UTC-4, Radey Shouman wrote:
Zen Cycle writes:

keyboard. IF I had to write those whole 10K+ lines of code from
scratch.....ugh.


I surmised that you enjoyed arguing about it because you continue to
do so.


To be clear, I haven't been arguing with you. For an example of my argument style, refer to my exchanges with tom. Rather, I enjoy the conceptual discussions. If you started on code structure, you'd put me to sleep.



In hardware,
everything happens at once, which can bite you in the ass.


Well, that's the first I've heard that concurrent task handling and
speed are a bad thing, though I do remember having to write
synchronizers into the combinatorial sections because the propagation
delay took us a bit by surprise. This wasn't exactly a bad problem to
have.


Where did I say it was a bad thing?


It was implied with "In hardware, everything happens at once, which can bite you in the ass. " I don't know about you, but except for certain fetishists, being bitten in the ass - either literally or metaphorically - is a bad thing.


That's why I continue to be mystified by your suggesting that a
complicated algorithm is used when a simple one would suffice.


Are you confusing me with someone else? I've taken the exact opposite position. I've stated repeatedly a simple math algorithm is more than sufficient, and I don't believe bike computer companies are using anything more than that.


*********
FPGA Conversions: ........

Pros: Low NRE (US$35k is about the lowest). Low minimum quantities (10k units/year).

Cons: High per-chip costs-- maybe 50% the cost of an FPGA. Low
performance, relative to the other solutions.
**************


High per-chip cost is totally unsuitable for this application.


maybe, it depends on the number of units being sold, size of the die, etc.... I wouldn't make that statement until a business case model was developed.


I think IoT is a
tool of the Devil, and would hate myself if I helped it spread.


LOL....I like that, I may use it the next time it's brought up in one
of our market requirements review meetings. I personally have no use
for IoT, but I have several friends and co-workers that want to run
their whole house from their smart phone. I tell them I'd rather ride
my bike.


*Someone* could run your house remotely, it just might not be you.


EXACTLY!!!

 




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