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826  Using Arduino / Sensors / Re: Looking for metal sensor on: April 09, 2014, 09:06:28 am
How will you drive a robot if there are a couple of magnetic object on the ground

To be successful,  you are probably going to have to improve your understanding of what you are actually want to detect.
Magnets ?
Pieces of iron that respond to magnets ?
Other objects ( mostly metals ),  which are electrically conductive ?
827  Using Arduino / Sensors / Re: DS18S20 giving slightly to high readings on: April 09, 2014, 09:02:05 am
People seem to  have odd ideas about temperature.   

You think 25 degrees is "brutally hot".    But a couple of days ago,   another guy was complaining about his device being too cold,   because he keeps his house at 27 degrees,  I think he said.

You need to calibrate your device against an ACCURATE thermometer.
828  Using Arduino / Sensors / Re: How to determine GPS accuracy? on: April 09, 2014, 08:46:31 am
One thing to be aware of,   is that many GPS chips can output their data in the NMEA text format,   and also in various binary formats.   This causes variations in the apparent resolution of the data.

For example,  the NMEA format as in the previous few posts,  on my GPS outputs 4 text decimal digits for the fractional part of the arc minutes,   which corresponds to 1 part in 10,000 for a minute,   which is 1800 metres for lattitude  and for longitude at the equator.   Changing the least signficant digit in this number therefore corresponds to a change in reported position of 0.18 metres.  About 7 inches.

But the binary format is a long in millionths of a degree,   which corresponds to a change in the reported position of 0.1 metres (  4 inches ).

Whether this difference in apparent resolution is "real" or "phony",  is hard to tell.     If you leave the device on the desk and collect a lot of the readings,  the statistical characteristics of the resulting outputs is the same,  but the granularity is different.

829  Using Arduino / Sensors / Re: How to determine GPS accuracy? on: April 09, 2014, 08:37:47 am
4717.112671   means  47 degrees and 17.112671 minutes.    To my mind,  that is a fairly bogus format but that is what they use.

To convert this to a fractional number of degrees,   you would calculate   47 + ( 17.112371 / 60.0 ),   and then you run into the effective limits of float variables.

830  Using Arduino / Programming Questions / Re: Word operation in Arduino on: April 09, 2014, 08:31:25 am
int lat_int=(int)latitude;
  float lat_float=(latitude-lat_int)*1000;
  int value=(int)lat_int;

This piece of code looks like nonsense.  What are you trying to do ?

lat_int is the integer part of the floating point number you started with.
lat_float is presumably supposed to be the fractional part, multiplied by 1000

You then make another int copy of lat_int  for no obvious reason,   and put two copies of it into your byte array.   And then you do nothing at all with the fractional part of the number which you calculated.

831  Using Arduino / Programming Questions / Re: Repeating code until condition is true on: April 09, 2014, 08:19:15 am
Your code has bigger problems than that.  What are you actually trying to do.

The first time though loop,   you calculate 'Time"  although one or both of the values in that calculation may have an indeterminate value.
832  Using Arduino / Microcontrollers / Re: Arduino Tre Price on: April 08, 2014, 03:17:48 am
When I had my web store for micro-controller stuff ...

How long ago, was that ?    Impossible to get anything sent from the USA for less than $30 USD now.
833  Using Arduino / Sensors / Re: Analog light sensor outputs are strange? on: April 08, 2014, 12:35:30 am
Are you connected to A0 or A1 ?  Make up your mind.
834  Using Arduino / Sensors / Re: Looking for metal sensor on: April 08, 2014, 12:27:51 am
It depends what you are trying to do.   Looking for gold nuggets ?   Lost coins at the beach ?   Nails in the wall ?  Sorting garbage ?

You might find it useful to google  "diy metal detector"  and read some of those.
835  Using Arduino / Sensors / Re: How to determine GPS accuracy? on: April 08, 2014, 12:18:02 am
The limitation is not caused by tinygps.   The limitation is what the gps module outputs.
836  Using Arduino / Sensors / Re: MPU-9150 + Leonardo Not Working on: April 08, 2014, 12:15:44 am
The first thing to do is find the sketch "i2c_scanner",   which scans the possible i2c addresses  and reports if it finds any devices.

Make sure you have connected the device to the correct pins for your kind of arduino.   Many advises say to connect to analog pins 4 and 5.   That is for Uno.   Others are different.  I don't know about Leonardo, you can check it.

Make sure you consider issues with 5v and 3.3v devices.

The MPU-9150 and 6050 require you to send them some configuration data.   It's not like other sensors which will just start to spit out data as soon as you power them on.
837  Using Arduino / Programming Questions / Re: Controlling How a Library Compiles From Within a Project on: April 08, 2014, 12:10:07 am
None of this is addressing the OP's basic issue.

I agree with him,  I have had the same issues.   Unfortunately,  I think this is an inherent weakness of the Arduino IDE scheme.  perhaps a necessary and reasonable one in the interests of perceived "simplicity" and the inherent project scale limitations of microcontrollers.
838  Using Arduino / Programming Questions / Re: Implementing Cordic Algorithm in Arduino on: April 08, 2014, 12:00:50 am
Well you need to go and understand  setup() and loop() before you will get very far.

All of those println() function calls in your alleged C program  will need to be replaced by Serial.println() to work on the arduino.
839  Topics / Robotics / Re: uArmⅠ:An open source robot arm on: April 07, 2014, 09:08:15 am
That robot seems to have 5 dof + 1 dof pincher.
840  Using Arduino / Sensors / Re: Looking for speed sensors on: April 07, 2014, 08:30:04 am
If you want to do this once,    make a video and measure the distance the ball moves between frames.
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