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676  Using Arduino / Sensors / Re: BMA180 + ITG3205 + HMC5883l Erratic i2c readings on: May 16, 2014, 05:04:24 am
I am also dubious about your I2c  reading function.

You are declaring the data array inside your i2c read function.   This data array wil go out of scope when the function returns,   and the pointer to it will be technically invalid.    This will probably work on the arduino anyway,   if you are not using interrupts,  but it is not correct coding.
677  Using Arduino / Sensors / Re: BMA180 + ITG3205 + HMC5883l Erratic i2c readings on: May 16, 2014, 05:01:01 am
For some reason,  the Bosch website does not list at BMA180,   although it does have BMA150, BMA220  etc etc.

Anyway,  it looks like you are putting the MSB and LSB of the data together the wrong way around.  That can certainly cause the behaviour that you are seeing.

Be aware that the acceleration reading can be positive or negative,   and learn how 2's complement integer representations work.
678  Using Arduino / Sensors / Re: BMA180 + ITG3205 + HMC5883l Erratic i2c readings on: May 16, 2014, 04:50:03 am
The BMA180 is a barometric sensor, isn't it ?
679  Using Arduino / LEDs and Multiplexing / Re: Building a 5x16 led matrix? on: May 16, 2014, 04:43:36 am
I didn't see any answer to your first question.

No,  you cannot increase the voltage that the Arduino operates at.
680  Using Arduino / Motors, Mechanics, and Power / Re: Converting 5v to 12v using an LM2577 - all i get is 4.8v? on: May 16, 2014, 02:41:50 am
The digital output of the arduino is not going to provide enough current to drive this,

If you have a very robust 5V supply available,  you could probably use this device to create 24 volts.   You could then use a relay to switch the 24V to the valve.   You can get suitable relay modules where the input can be driven by an Arduino output.

You would need to check what the operating current of the valve is,  to make sure you can provide enough current to drive it.
681  Using Arduino / Motors, Mechanics, and Power / Re: trying to set a home position. on a contentious run servo on: May 16, 2014, 12:56:13 am
Your homeset() function will only run once,  in setup().

But I fail to see why you are using a continuous servo at all.   Setting the home position isn't really going to help you much,    why don't you manipulate your color wheel with a regular position-controlled servo ?
682  Using Arduino / Motors, Mechanics, and Power / Re: Arduino controlled 72v 350a DC Motor on: May 16, 2014, 12:52:44 am
The only odd thing I see on your diagram,  is the "low current fuse",   which appears to be in the high current path.

If that is supposed to be a low current fuse to protect the low voltage electronics,  you might need to move it about an inch to the left.
683  Using Arduino / Motors, Mechanics, and Power / Re: Arduino controlled 72v 350a DC Motor on: May 16, 2014, 12:38:43 am
The speed from a gps device is not really going to be reliable enough for motor control.  It works ok when you are cruising along,  performs poorly when you stop and start.
684  Using Arduino / Programming Questions / Re: Program does not go into the switch statements at all ! on: May 16, 2014, 12:33:05 am
It seems odd to me,   that when you read your char,   and if it isn't a comma you stick it in your array,   it seems odd to me that there isn't a  "  fieldIndex++ ;  "   immediately after you stick it in the array.
685  Using Arduino / Programming Questions / Re: GPS bearing heading on: May 15, 2014, 08:42:56 am
GPS does not have a compass.   Some GPS receivers might also have a compass,  but that is not part of the GPS system.

GPS devices can tell which way you are moving.   They do this, not by a compass,  but by comparing the current GPS position to the previous GPS position.   If your current GPS latitude and longitude represents a point which is 20 metres north-east of where you were 5 seconds ago,   then the GPS device can calculate that you seem to be moving north-east at 24 kilometres/hour.   There is no compass,  no direction,  and no heading involved in this calculation,   it is based on the calculation of moving positions.   

GPS has no knowledge of heading,  or "which way you are facing".    It would give you the same answer if you are driving backwards.
686  Using Arduino / General Electronics / Re: Meaning of the term 'grounded' and direction of electron flow on: May 14, 2014, 07:19:19 pm
Quote
I am aware that when an electron is grounded it loses its charge and reverts to a low energy state.

That's nonsense, right there.

687  Using Arduino / Programming Questions / Re: error: invalid conversion from 'volatile byte' to 'void (*)()' on: May 14, 2014, 07:17:56 pm
In the code you posted in reply #9,   you almost certainly need a {  on the line after   If(millis().....     (  about the third line of loop( ) ).
688  Using Arduino / General Electronics / Re: 5:1 AC Step Down Transformer on: May 11, 2014, 11:28:10 pm
If you simply want to measure or detect this signal,   and you want to reduce the voltage for compatibility with an A/D converter,  or something,     then the simple answer is a voltage divider using two resistors.
689  Using Arduino / General Electronics / Re: 5:1 AC Step Down Transformer on: May 11, 2014, 11:25:36 pm
Do you want to buy one,  or make one ?

Why would you want to do this ?  It seems rather pointless.   Nobody else wants to do it,   which is why such a product probably doesn't exist.

If you want to try making one,  there are plenty of online tutorials and youtube videos about how to make your own transformers.
690  Using Arduino / Programming Questions / Re: Usin a RAW value of a variable. on: May 11, 2014, 11:20:08 pm
It means what it says.

You have defined the function to receive a char*  as the first argument.

And then you try to invoke the function with an int* as the first argument.

I am dubious about the compilers claim that a pointer is not a pointer.  It's a pointer.

But anyway,   you need to consider what you are trying to do.     Do you want the function to have a char,  or an int ?  Make up your mind.
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