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1831  Using Arduino / Sensors / Re: RDM880 rfid reader on: April 02, 2013, 10:05:04 am

This probably won't work very well.

Everything is working fine

Show us the code that is working fine.

However when i want to use commands specified in the datasheet it is not working.

What does "not working" mean? Do you get nothing back? Do you get garbage back? Do you get unexpected card numbers?
Have you tried the command without executing the halt command (replace 0x01 by 0x00 in your command sequence)? Where did you get your definition of what "HALT" means? According to the ISO14443-3 standard ( halt means the card stops it's activity and reacts only to WAKE-UP commands anymore. In my interpretation this is not your intended action. All cards treated that way may have to be reactivated with a wake-up command.
1832  Using Arduino / Project Guidance / Re: Getting 640x480 images from camera modules at 1FPS on: April 02, 2013, 06:59:14 am
Can you give me about example code

Where's the link to the product you're using? How have you wired it to the Arduino? What do you want to achieve?
1833  International / Deutsch / Re: OneWire auf dem Arduino Due falsche werte on: April 02, 2013, 05:07:28 am
Ich wiederhole meine Frage: Wie hast Du den Sensor angeschlossen? Geht der Widerstand von 4k7 gegen 5V und dann an die Datenleitung? Wenn ja, dann ändere das mal und mach den Pull-up nach 3V3 und nimm einen anderen Eingang am Due, denn den ersten dürftest Du bereits verbraten haben.
1834  International / Deutsch / Re: Buffergrößen in der SdFat ? on: March 28, 2013, 09:14:24 pm
Die Puffergrössen sind gegeben durch den SD-Kartenaufbau. Du musst immer einen Block lesen oder schreiben, brauchst also einen 512 Bytes grossen Puffer.

ich habe auf dem MEGA einen größeren Sketch, wo der SRAM knapp wird.

Was hast Du denn im Speicher, dass Du 8kB RAM füllst? Vielleicht können wir Dir ja helfen, den Speicherverbrauch etwas einzudämmen.
1835  International / Deutsch / Re: Brushless ESC/motors = Drehzahl on: March 28, 2013, 09:00:17 pm
Eigentlich steuerst Du den Brushless Motor über eine Elektronik mit der gewünschten Drehzahl an. Wenn Du dort nicht an die Drehzahl ran kommst, kannst Du die Impulse pro Windung zählen, um an die RPMs zu kommen. Voraussetzung ist, dass Du den inneren Aufbau des Motors kennst, sonst kannst Du die Umsetzung von Impulsen zu RPMs nicht machen.
1836  Using Arduino / Programming Questions / Re: problem on Analog read on Piezo sensors for triggering + timelapse on: March 28, 2013, 08:53:13 pm
Maybe you have to define what a noteOn is. One possibility is to register just rising edges. So if the value is bigger than 600, register you "noteOn", then ignore all values until they go below 500. As soon as you got the first reading below that, start looking again for values greater than 600. Does that make sense in your case?
1837  Using Arduino / Project Guidance / Re: Need more pins for project - SPI unused and rewriteable? on: March 28, 2013, 12:47:29 pm
How do I go about setting the analog as a digital pin?

Just use pinMode() to set the correct direction, then digitalRead() or digitalWrite() to read/write to/from it. It's best use and most portable to use the A0, A1, etc. place holders for the pin numbers.
1838  Using Arduino / Programming Questions / Re: Question on attachInterrupt function? on: March 28, 2013, 12:41:51 pm
why not stay in an interrupt for ages, does it do damage at all or just not good coding?

It does no damage but it's a special state and all the other interrupts are disabled meanwhile. This results in millis(), delay() and other stuff is not working, you cannot print to the serial interface, you cannot use the I2C or SPI interface, you're more or less caught there.

Interrupt handlers should be very small and fast. Everything that takes more than a few microseconds should not be done in the interrupt handler but moved to the loop and activated by a flag variable.
1839  Using Arduino / Programming Questions / Re: problem on Analog read on Piezo sensors for triggering + timelapse on: March 28, 2013, 12:37:48 pm
One call of analogRead() takes about 100µs, so loop() is run about 2500 times per second. If the piezo is active for more than about 40 ms you get it registered twice. It seems like the first piezo was active for about one tenth of a second and you got 3 registrations.

If you haven't connected the other piezos, the appropriate pins are probably floating (not connected to anything), so they give you readings of a more or less random value. Connect these pins to GND and they should go away.

1840  Using Arduino / Project Guidance / Re: Correct Arduino BT board to buy for image transfer project on: March 28, 2013, 12:24:54 pm
I don't know why you're fixed to the BT. If you can live with WiFi as the wireless medium you might have the possibility to use a WiFi Bee ( together with a USB Host Mini ( This is not fast and definitely not an elegant solution but it might work and is really small.
1841  Using Arduino / Project Guidance / Re: Need more pins for project - SPI unused and rewriteable? on: March 28, 2013, 12:15:54 pm
The Ethernet functionality uses SPI. Do you already use the analog inputs? If not, they can be configured as digital I/Os too.
1842  Using Arduino / Project Guidance / Re: Measuring ac using arduino on: March 28, 2013, 12:14:02 pm
You want to measure current without a current sensor? That's impossible. But probably you have some special current sensors in mind that you want to avoid. You have to specify which current sensors you want to avoid. Even a shunt resistor is a current sensor...
1843  Using Arduino / Project Guidance / Re: Switching on DC loads through LCD menu? on: March 28, 2013, 12:11:35 pm
What i DO have is the "loading screen" that i want the system to show when power is applied, but how do i make so that this only shows once when power is applied, and doesn't go "in the loop" so to speak?

Put it into the setup().
1844  Using Arduino / Sensors / Re: SensorTechnics i2c Pressure Sensor on: March 27, 2013, 06:50:55 pm
In the datasheet I cannot find any reference that the sensor supports an I2C write. The I2C scan code does a write and that maybe is the problem. What does the code I wrote for you return? You may also check the return value of Wire.requestFrom(), it should return 2 if the sensor really returned data.
1845  Using Arduino / Programming Questions / Re: Using C, C++ functions in Arduino IDE on: March 27, 2013, 06:39:14 pm
MEGA2560 has 8k expandable to direct-address 64k and there's a bank-switched 512k shield....

And then there's the Due which is a 48 MHz 32-bit ARM with lots of RAM, a world apart from an UNO.

Does that mean you think the AVR-libc should support "%f" in it's print and scan functions just because there is an 8k version of an ATmega controller?

The Due is another league and therefore has a separate forum. IDE support for it is in beta.
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