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1  Using Arduino / Project Guidance / Re: Are there any small Arduino boards with Ethernet built-in? on: April 15, 2014, 02:45:55 pm
I don't know if you're interested in wifi, or only Ethernet, but these boards look interesting:  https://www.spark.io/

Tiny boards with built-in wifi.  And cheap!  Seems like an awesome idea, but I don't know much about them.  Maybe someone else has some experience with them?
2  Using Arduino / Project Guidance / Re: sim card for GPRS shield in USA on: April 15, 2014, 02:43:00 pm
Does anybody have a SIM provider suggestion?
3  Using Arduino / Project Guidance / sim card for GPRS shield in USA on: March 08, 2014, 09:51:39 pm
I've got a GPRS/GSM shield that I'd like to use, but I don't know where to get a SIM card for it.   I'd like to get a pre-paid one instead of signing some kind of agreement with a carrier, but is that possible?  It seems like lots of people are successfully using GPRS/GSM shields but I can't find any mention of what type of sim card or carrier people are using here in the US. 
4  Using Arduino / Interfacing w/ Software on the Computer / ethernet logger posting to remote file with php on: January 28, 2014, 02:16:26 pm
I have a logger that I built using the new Uno+Ethernet board. It records data from a bunch sensors, and puts all of the values into a string. I'd like to transmit that string every 10 minutes via the internet to a remote server that's running a php script that will append the incoming string to a text file on the server. The problem is that I can't find any examples of a php script that will do this. I know absolutely nothing about php scripts, so I'm looking for a basic examples that takes the incoming string from the arduino's GET or POST request and just appends it to a text file. I've found enough examples of Arduino sketches to figure out how to transmit the string, I just need help on the php side. Thanks!
5  Using Arduino / Programming Questions / Re: converting captured string to floats on: November 06, 2013, 11:21:58 am
I finally found a solution that is pretty simple and seems to be capturing the data correctly, using the parseInt() and parseFloat() functions.

Code:
  if (mySerial.available() > 0) {
    int x = mySerial.parseInt();
    float y = mySerial.parseFloat();
    int z = mySerial.parseInt();
    }
 
6  Using Arduino / Programming Questions / Re: converting captured string to floats on: November 04, 2013, 11:33:16 am
I thought there were going to be some new-fangled parsing functions included in the new Arduino 1.0 IDE, but I can't seem to find how they might be used in this case.
7  Using Arduino / Programming Questions / converting captured string to floats on: November 04, 2013, 10:25:33 am
I have an arduino device that captures incoming serial data from a sensor in the string that is made up of three numbers, separated by spaces, and ending with a letter, usually looks like this:    -24 55.5 243t

I used to have an older sensor that outputted 3 integers, which was easy to parse using the following code.  But now that the middle number is a float, my code breaks.  I know that not many people recommend using the scanf() function anyway, and it appears it doesn't work for floats.  I can't figure out how to use atof() on an array like this one.  Is there a better option that I should try?

Code:
int x,z;
float y;
String testString = "-15 22.8 402t";

void setup()
{
  Serial.begin(9600);
}

void loop() {
  
  Serial.print("testString = ");
  Serial.println(testString);  //so you can see the captured string
   char Carray[testString.length() + 1]; //determine size of the array
   testString.toCharArray(Carray, sizeof(Carray));
  Serial.print("Carray = ");
  Serial.println(Carray);
   sscanf (Carray, "%d %f %d", &x, &y, &z);
  Serial.println("THE DATA:");
  Serial.print("first= ");
  Serial.println(x);
  Serial.print("middle= ");
  Serial.println(y);
  Serial.print("last= ");
  Serial.println(z);
  
  delay(5000);  

  }
8  Using Arduino / General Electronics / calculating battery life with intermittant load on: February 06, 2012, 11:34:55 pm
I've got a circuit that draws 15ma when powered on, and draws no current when off.  If it's only active for 5 seconds every 5 minutes, how long will it last if I have a battery pack with a 2000mAh capacity? 
9  Using Arduino / Programming Questions / XML parsing on: October 28, 2011, 02:30:38 pm
I have a device that is outputting XML data via a serial line every few seconds.  I need to interface an Arduino with it to parse the data and then do some other stuff with the values it gets.  This is a standalone portable unit that only exports XML and I don't want to connect a PC or something else to handle the data.  I'd like the Arduino to do the parsing if it's possible.  The datastream looks like this:

<data><celltemp>5.13581e1</celltemp><cellpres>1.01388e2</cellpres></data>

What is the preferred method for parsing the two number string out of the above text and once I do that, is there a good method for converting 1.01388e2 to 101.388.

10  Using Arduino / Networking, Protocols, and Devices / Re: sending text strings through xbee mesh on: October 08, 2011, 04:39:22 pm
Each of my arduino logger nodes have unique names anyway, so it's not a problem to tack that on to the beginning of the string.  I just wasn't sure if API mode was more efficient in terms of the actual packets that are being transmitted, or am I losing some cool features of API mode if I choose transparent mode.
11  Using Arduino / Networking, Protocols, and Devices / sending text strings through xbee mesh on: October 07, 2011, 11:20:06 pm
I've been working my way through Rob Faludi's WSN book, and I have successfully sent text strings from one arduino to another using my series 2 ZB xbee units in transparent mode.  I also did his example of having 3 router/endpoint nodes transmitting temperature data to a coordinator with API and displaying the live data on the Processing thermometer graph.  But those nodes sensed the temperature from a sensor on their own analog input pins.   I have arduino-based loggers with multiple sensors on them that require a more complicated interface than I can achieve with the onboard I/O of the xbee.  Currently the loggers just write the data to an SD card, but I'd also like to transmit it via the xbee.  How do I go about sending a string of text through the mesh and have it arrive in one piece at the coordinator?  Is it simply a matter of saying "Serial.print("23 degrees, 0.58 cm, 4.5 volts") on the serial input of the end node, or do I have to use a special protocol?
12  Using Arduino / Programming Questions / best method for implementing a timer on: September 12, 2011, 10:30:07 pm
I'm building a device with an Uno that'll have an LCD display showing the length of time (mm:ss) that has elapsed, and then every 5 minutes it'll need to be reset to 00:00 and started again.  The catch is that during the period it's showing the time, I also need to be reading a few sensor inputs and outputting some serial data, so I can't simply use a delay for the timer.

Should I just use Timer0 and millis to do some arithmetic, like:  if(currentMillis - previousMillis > interval)....   so it'll only update the display when a certain interval (1000 millis) has passed, meanwhile the main loop will keep looping and doing other stuff.

or is there a timing library that would be easier to help keep track of seconds and minutes?  I'll also have a DS1307 RTC onboard, so should I just poll that every loop to get the current time and then do the math like above?
13  Using Arduino / General Electronics / Re: how to get a stable 5v reference on: July 20, 2011, 06:03:20 pm
That looks great, thanks!  There are so many ADC chips out there that I've had a hard time trying to figure out which one to use, but that one seems like a good one to start with.
14  Using Arduino / General Electronics / Re: how to get a stable 5v reference on: July 20, 2011, 12:27:59 pm
So use  the 5V 1A switching regulator, will be a very stable 5V source for your 25mA plus the arduino's 30mA.
Use the analog devices SPI ADC that's been posted previously with 6 sample & hold inputs & get 6 conversions at the same time.

Do you happen to know the part number of that ADC?  I've been searching for days and haven't found one with 0-5v input and multiple channels.
15  Using Arduino / General Electronics / Re: how to get a stable 5v reference on: July 19, 2011, 09:48:04 pm
yes, but I'm using a precision 3.3v regulator as the external reference voltage for the Atmega328, so if the 5v excitation voltage varies, the output of the sensor compared to the stable 3.3v varies as well.
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