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4621  Using Arduino / Programming Questions / Re: Controlling Servos on: September 17, 2013, 10:58:18 am
Making something flap like a bird is entirely feasible.

Making it capable of flying is massively harder and I suggest you abandon any thought that the static flapping model powered by servos will ever actually fly.
4622  Using Arduino / Project Guidance / Re: help needed asap on: September 17, 2013, 10:51:35 am
Yes. You are right. Already I read about videoExperimenter shield. And I observed the LM1881 IC on that shield. But now I have this IC separately. So my question is, Can I using this IC and get the signal then send it to my Arduino for processing is possible or not? And is it possible to process when I don't using videoExperimenter shield? Please give some suggestions asap.   

Almost anything is possible if you're willing to throw enough time and money at it. Whether you can do it is another matter. If you want to do something similar to the video experimenter board without using the board then you need to understand what it does and how it does it, and be capable of developing something similar. Do you and are you?
4623  Using Arduino / Project Guidance / Re: Looking for a code to check if bluetooth is paired or not on: September 17, 2013, 10:48:29 am
I'm not familiar with that device but Google suggests that it provides a text-based command interface so I suggest you review the command syntax and see whether there are any commands to report the connectivity status.

Alternatively, you may find that it can be inferred from the RTS/CTS outputs.

You also have the option of using a keepalive so that you get positive confirmation when the adapter is paired and successfully communicating.
4624  Using Arduino / Project Guidance / Re: Controlling DC motor (2 directions) with 4 transistors? on: September 17, 2013, 10:37:20 am
What you're trying to achieve would be a H-bridge circuit. You can buy Arduino shields and compatible boards providing this, but there's no reason not to make your own if you want to tackle the electronics yourself. I can't tell whether the circuit shown in your picture is correct, but you could Google H-bridge driver circuit to see how it's supposed to look, and also look for the circuit diagram for standard H-bridge drivers (I guess there will be some published schematics somewhere).

Also measure the voltage drop across each of your transistors when it is supposed to be fully 'on' and compare that against the expected forward voltage drop for that transistor type - it may be that you are using an unsuitable transistor type, or not turning it fully on.
4625  Using Arduino / Project Guidance / Re: Hi speed video camera on: September 17, 2013, 10:32:51 am
It might be cheaper to use the "bullet time" approach and just use a separate camera per frame, triggering them all from a central controller. This seems like an expensive approach too, but it might still work out cheaper than spending tens of thousands of pounds on a really, really fast high commercial camera.
4626  Using Arduino / Project Guidance / Re: Ultrasonic dist. meter reading water level? on: September 17, 2013, 10:27:00 am
I've read that it works more reliably if you bounce the pulse off a float with a smooth reflective top surface, rather than trying to detect the water surface directly.

And, you need to get rid of the duplicate thread you started.
4627  Using Arduino / Project Guidance / Re: File transfer from SD card to website via GSM modem on: September 17, 2013, 08:31:55 am
What I'd like to be able to do is take a file from the SD card and upload it straight to a website using the modem. To be honest, I'm hoping there's a library out there that someone's already written to do this! I've seen a few posts on this forum that relate to this, but I've yet to find anyone who's publicly documented a solution.

I think that what you need to do is use extended AT commands to initiate an HTTP connection and then carry out an HTTP request that uploads the file content. There are a couple of ways you can do that in HTTP. I suggest you start by implementing the web server part that presents a page you can use to upload the file interactively. Use Wireshark to see what HTTP request actually goes over the wire when you upload the file. Then modify your sketch to send a similar HTTP request (via the AT extended interface), changing parameters like data length and content as required.

You should find an example with the GSM library that demonstrates how to use the AT extended interface to send an HTTP request and read back the response.
4628  Using Arduino / Programming Questions / Re: Serial Call and Response (handshaking) with ASCII-encoded output help on: September 17, 2013, 08:26:46 am
I was getting the error message: Cannot find anything named "Serial"

Where are you getting this error - is it when building the Arduino sketch, or the Processing application?
4629  Using Arduino / Programming Questions / Re: Works there but not here :( Anyone see why ???? on: September 17, 2013, 08:22:31 am
The code you posted is incomplete.
4630  Using Arduino / Programming Questions / Re: Track minutes per day a valve is on on: September 17, 2013, 08:17:56 am
I'd like to know if anyone has a simpler way.

Poll the state of the valve as frequently as you like. Remember the previous state, and compare with the new state to see whether the state has changed. There is an example sketch demonstrating this 'edge detection' logic. I recommend including some debounce logic so you don't get multiple triggers when the valve is moving (there are example sketches demonstrating this, too).

If the valve state changes from OFF to ON then record the current time in a variable.
If the valve state changes from ON to OFF then subtract the 'on' time you recorded earlier from the current time to get the elapsed time it was on for. Add this to an accumulator.

Use the logic PaulS mentioned to reset the accumulator and restart timing at midnight.
4631  Using Arduino / Programming Questions / Re: Alternative to millis() on: September 17, 2013, 08:10:04 am
By my reckoning, nine hours is about how long it would take to overflow a signed int that was being incremented once a second. If that's the technique you're using for counting the passage of time, you're doing it wrong.
4632  Using Arduino / Project Guidance / Re: Accelerometer for measuring rpm on bicycle on: September 17, 2013, 07:57:49 am
Does each Xbee transmitting sensor data require an Arduino? I think it most likely does, just need clarification

Actually, they don't. However, they only provide a limited interface and depending what sort of interface your accelerometer provides you might need an Arduino to act as a bridge between that and the XBee. If you're using an accelerometer with an analog interface, you could feasibly connect that directly to the transmitter XBee, and use an Arduino to read the analog signal from the receiving XBee. Similarly if your accelerometer provided a serial interface (I don't know how likely that is) you could connect the serial output directly to the transmitter XBee and have the Arduino read the same serial stream from the receiving XBee.
4633  Using Arduino / Project Guidance / Re: Help to send simple commands to computer using Arduino Uno on: September 17, 2013, 07:49:08 am
For goodness sake don't connect that concoction to your Arduino - it will be outputting RS232 signaling which is way outside the voltage range the Arduino can tolerate.

As Nick_Pyner says, you need to step back and look at the example sketches that come with the Arduino - they show you how to send and receive data over the USB connection to the PC.
4634  Using Arduino / Project Guidance / Re: Using an Uno to Control a Robotic Arm? on: September 16, 2013, 07:36:28 pm
How much torque do you need to generate, and what voltage and current supply are you budgeting for? Physically how big can the motor/gearbox assembly be?
4635  Using Arduino / Programming Questions / Re: Write negative floats to EEPROM. on: September 16, 2013, 05:34:18 pm
Here is my solution to the problem.

You seem to be making a simple problem very complicated. If you just define a variable that holds the data you want to store in EEPROM (be that a byte, int, float, struct or whatever) you can make a single call to EEPROM_readAnything() to read EEPROM content into the variable and a single call to EEPROM_writeAnything() to write your variable to EEPROM. How much simpler could it be?

Code:
struct config_t
{
    long alarm;
    int mode;
} configuration;

void setup()
{
    EEPROM_readAnything(0, configuration);
    // ...
}
void loop()
{
    // let the user adjust their alarm settings
    // let the user adjust their mode settings
    // ...

    // if they push the "Save" button, save their configuration
    if (digitalRead(13) == HIGH)
        EEPROM_writeAnything(0, configuration);
}
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