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1771  Using Arduino / Networking, Protocols, and Devices / Re: XBee interferes with USB serial on: April 09, 2013, 12:38:35 pm
On an Arduino UNO the USB connection is converted into a serial interface with the onboard ATmega16U2 "coprocessor" and the fed to the serial interface of the main processor on pin 0 and 1. If you connect a XBee to these pins you cannot use the USB serial at the same time as you use the XBee. If you need a debug serial, buy a USB2Serial converter (p.e. the USB2Serial Light from Arduino) and connect it to two other pins and install a SoftwareSerial on these pins. Another possibility is to use an Arduino Leonardo which handles the USB connection directly in the main processor and  leaves the serial interface free for you to use even when using the USB connection for debugging. The hardware serial is available via the Serial1 object to the sketch then.
1772  Using Arduino / Networking, Protocols, and Devices / Re: WiFi Shield V2.0 for Arduino on: April 09, 2013, 12:32:31 pm
There is no link to the product page (it's not an original Arduino product) and there is no link to the library you used.

From the picture it looks like it's a Cuhead Wifi Shield V2.0. You cannot use the Wifi library of the IDE with this shield. You need another library for it.
1773  Using Arduino / Networking, Protocols, and Devices / Re: Simple questions on Arduino Wifi shield - can it do this (socket?)? on: April 09, 2013, 12:20:39 pm
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Just being naive here, will client.connect("myServer.com",1035); possibly replace that socketDialSD()?

It's not a direct replacement but it does more or less the same. Both open a connection to a server.
1774  Using Arduino / Networking, Protocols, and Devices / Re: Can the Uno handle two serial port functions ? on: April 09, 2013, 12:17:53 pm
Quote
I will try the SoftwareSerial library which should allow me to use pins (other than 0 & 1)  because I am concerned about communication issues if pin 0 & 1 are shared for both my serial device and the USB to the PC unless I can see some example code that works...

What do you want to do? If you want your UNO to be a USB2Serial device you can just connect it via USB to your PC and connect the TTL serial device to pins 0 and 1. VoilĂ , you have your USB2Serial. You don't need any software to be run on the UNO, it acts as a USB2Serial converter.
If you need something else than a USB2Serial converter, tell us what you want to achieve!

The SoftwareSerial class works OK for baud rates up to 9600, with some devices even up to 38400. I personally never got beyond that limit.
1775  Using Arduino / Networking, Protocols, and Devices / Re: Ethernet shield / WEB server / string issues on: April 09, 2013, 12:12:16 pm
You're wasting your RAM!

Don't use the String class. It has two problems: it's programmed for a full-fledged PC with a memory management unit where RAM is not an issue. It fragments the available memory making it impossible to allocate bigger memory chunks in no time. Additionally it suffers from an implementation bug in the dynamic memory allocation within the avr-gcc code leading to memory leaks.

The use the F() macro! All classes inheriting from the Print class (almost all having the print() and println() methods) allow you to use the F() macro for constant strings (literals specified in double quotes). These constant strings are the read directly from the flash memory avoiding to make a copy of them in the RAM.
Example:

Code:
client.println("<p>This is just an example with some text provided as a constant</p>");

becomes

Code:
client.println(F("<p>This is just an example with some text provided as a constant</p>"));
1776  Using Arduino / Networking, Protocols, and Devices / Re: Can the Uno handle two serial port functions ? on: April 09, 2013, 11:44:53 am
Quote
Does anyone know if a Uno be used as a Serial to USB converter with the use of
the SoftwareSerial library or is this only for Leonardo & Mega arduinos?

You don't need the SoftwareSerial library just for a Serial2USB converter because the UNO has one onboard. Just connect the USB and put the serial device on pins 0 and 1 and you have a USB2Serial device.
1777  Using Arduino / Project Guidance / Re: Mcp4261 Digital Potentiometer + Arduino on: April 09, 2013, 11:42:06 am
I don't see any reason for this. Seems to be a standard SPI device that should run with the included SPI library.

Show us the code you used for your tries!

Make a picture or a drawing of how you wired the chips to the remote.
1778  Using Arduino / Project Guidance / Re: INterfacing Arduino with a USB output on: April 09, 2013, 11:33:08 am
You might be successful using the USB Host Shield https://www.sparkfun.com/products/9628. What has the Arduino to do with the data it receives from the mouse?
1779  Using Arduino / Project Guidance / Re: How to OCR digits real time and use that value in Arduino? on: April 09, 2013, 11:30:00 am
Yes, this is possible but has then nothing to do with the Arduino. As long as you're able to do the OCR somehow on the PC you can send that value to the Arduino by USB (or TCP/IP if you have an Ethernet Shield).
1780  Using Arduino / Project Guidance / Re: Printing with an Epson M150-II Micro Dot Matrix Printer on: April 09, 2013, 11:27:06 am
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Does it seem feasible to drive this printer mechanism from an arduino uno?

Yes, it does. The UNO is fast enough to drive the pins in a high enough frequency and need about 6 GPIOs while the UNO has 20 of them.
In the project I would spend one Arduino to drive the printer only (no other tasks) because else you might get difficulties staying within the timing limits (depends a lot on what else you thought the Arduino might have to do).
1781  Using Arduino / Project Guidance / Re: GSM Shield and SimCard Requirement on: April 09, 2013, 11:13:04 am
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Here is my specific question. what if I am the owner of the network and I make it open to everyone do I still need a simcard?

Yes, you need one (the SIM contains the phone identification, in the case of the GSM shield the Arduino is the phone) but it can be any SIM because you can configure which IMSI (that's the identification number in the SIM) you want to give access to your network.

Just out of curiosity: Where in the world are you living that you're allowed to make your own GSM network?
1782  Using Arduino / Project Guidance / Re: RFID project on: April 09, 2013, 11:00:57 am
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Wich components should I use best?

We have no chance to give you a good suggestion with so little data of your project. You don't tell us what you want to do with that project and you write nothing about limitations (technical, financial) you have.

Quote
Is it possible to add a rfid and a wifi shield together?

It's possible but depends on what hardware you'll be using.
1783  Using Arduino / Project Guidance / Re: How to OCR digits real time and use that value in Arduino? on: April 09, 2013, 10:54:03 am
An Arduino is much too slow to do any OCR, it even won't process the image data stream of webcam.

Use a more powerful platform for this (e.g. Raspberry Pi, Cubieboard, etc.).
1784  Using Arduino / Sensors / Re: IDG500 Breakout Board Sensor - How Do I Find a Header? on: April 09, 2013, 10:08:32 am
Use one of these and cut it to the right width https://www.sparkfun.com/products/115.

Edit: Or these if you want to have the male variant: https://www.sparkfun.com/products/116.
1785  Using Arduino / Sensors / Re: Fast 16bit ADC using Arduino Due and AD977 on: April 09, 2013, 10:05:08 am
The relevant line is probably this one:

Code:
  int volts=((4980470*response1)/255)+((19530*response2)/255);

Hint: call variables so that the content is best described. If it contains microvolts, don't call it volts.

Then use the correct shifting:

Code:
  int microvolts = (((uint32_t) response1) << 8 | response2) * 76;

First we create a 16bit value from the two bytes, resulting in a value in the range 0 - 65535. The upper limit multiplied by 76 gives 4980660, which should be sufficiently accurate for your usage.
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