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841  Using Arduino / Programming Questions / Re: Arduino + Ethernet + DS1307 overflow(?) error on: June 13, 2012, 01:52:50 am
Do you use this libary ? http://arduino.cc/playground/Code/Time

I'm looking at the library right now, but it is not easy to understand.
You could have a ram or stack overflow, or the Time library could have problems with rollover.

You check timeStatus() for timeSet, but can you check which value it is ? Is it "timeNotSet" or "timeNeedsSync".
If it is "timeNeedsSync" you might just ignore that value and try once more.

You might have a rollover problem in you own code.
If you use millis() for example.
Can you measure somehow how long it takes to freeze ? Is it the same every time ?
842  Using Arduino / Microcontrollers / Re: Atmega32 support for arduino 1.0.1 on: June 13, 2012, 01:39:25 am
The question has been asked before : http://www.arduino.cc/cgi-bin/yabb2/YaBB.pl?num=1281368658

The answer was: It's not going to work.
843  Using Arduino / Microcontrollers / Re: Debugging UNO standalone - Help needed on: June 13, 2012, 01:35:18 am
That's hard to tell, because there are many things that could be wrong.
The information you give is just a fraction of what would be needed to pinpoint the problem.

Did you try to use the original Uno firmware for both chips ? Does the Arduino Uno use Optiboot? I'm not sure about that.
If you did, the might be something wrong with the hardware of the ATmega16u2. Can you check that once more againgst the schematic of the Uno ?

But why not use an Arduino Uno in the first place ? It already acts as a com-port to the PC, and it is working.

Did you check out the new Arduino Leonardo ? The Arduino 1.0.1 has already examples for the Arduino Leonardo to make it behave like a keyboard of a mouse with its USB bus.
844  Using Arduino / Programming Questions / Re: 74HC595 basics on: June 13, 2012, 01:26:43 am
Don't cross-post:

http://arduino.cc/forum/index.php/topic,109704.msg823827.html
http://arduino.cc/forum/index.php/topic,109711.msg823866.html
http://arduino.cc/forum/index.php/topic,109719.msg823901.html
http://arduino.cc/forum/index.php/topic,109713.msg823871.html
845  Using Arduino / Sensors / Re: Would a 3v Negative Voltage Spike Damage the A/D converter? on: June 12, 2012, 11:24:37 am
It might damage the input.

You can use a resistor of 1k to 10k in series with the input.
That will almost not reduce the maximum input frequency, due to the high impedance of the input.

If you use a diode, use a schottky diode. Most of them can handle high frequencies with ease.


What is the minimum pulse length for an interrupt ? I think it is about 100ns, but I can't read it in the datasheet.
846  Using Arduino / Microcontrollers / Re: Read an ATtiny13 on: June 11, 2012, 05:39:30 pm
Why not buy a very cheap USBasp programmer and read the firmware and also read the fuses.
That way you can always set the original firmware and fuses back.

Once you have that working, you could use the Arduino as an ISP.
This is a good starting point: http://arduino.cc/en/Tutorial/ArduinoISP
847  Using Arduino / Sensors / Re: Gyroscope-L3G4200D & Arduino Mini Pro Compatibility on: June 10, 2012, 08:17:23 pm
The original Arduino Pro Mini is with an ATmega168. But everything should be the same.
I would prefer a Uno, Nano or Pro Mini with an ATmega328.

If the Arduino board doesn't have the 3.3V on board, you could use that sensor from Pololu, which has a voltage regulator itself and even an I2C voltage shifter ( http://arduino.cc/playground/Main/I2CBi-directionalLevelShifter ).

The Nano has got an 3.3V on board. In that case you don't need the sensor board with voltage regulator and you can do without the I2C level shifter.

How to use the pins, is reading the datasheet and checking the Pololu schematic.

CS: datasheet: "1" for I2C. Pololu schematic: already "1" with pull-up resistor.
SDO: datasheet: in I2C mode SDO = SA0, lowest bit of address. Pololu schematic: pulled high, addres bit is '1'.
According to table 13 of the datasheet, the I2C-address will be 0xD3 for reading, and 0xD2 for writing.

So you connect Vin to +5V and connect GND, SCL, SDA. That's it.

The L3G4200D is not yet in the Playground sensor section: http://arduino.cc/playground/Main/InterfacingWithHardware#motion_accelerometer
848  Using Arduino / Sensors / Re: MPU-6050 how to change rate of MPU generated fused data on: June 10, 2012, 07:54:44 pm
You sure take a deep dive into the MPU-6050.

These pages:
http://permalink.gmane.org/gmane.linux.kernel.iio/4339
http://permalink.gmane.org/gmane.linux.kernel.iio/4346
have a function inv_init_config(), which sets the fifo rate at 50Hz. Is that of any help ?

You could ask Jeff.
849  Using Arduino / Sensors / Re: gyroscope L3G4200D on: June 08, 2012, 06:12:51 pm
If you read the datasheet more carefully, it's all there.

DR = Data Rate : two bits for the output data rate in the CTRL_REG1 for 100/200/400/800Hz
BW = Band With : two bits for the Bandwidth selection in the CTRL_REG1. See the table for the Cut-Off.
How this Cut-Off is actually used, is not very clear in the datasheet.
It is used in combination with the filters.
HPF = High Pass Filter. Higher frequencies are passed. Slow motion is filtered out.
LPF = Low Pass Filter. Higher frequencies are blocked, to reduce noisy or jumpy results.

What the best settings are, is hard to tell. You might look for a good example and use that.
850  Using Arduino / Sensors / Re: are these ADXL345 accelerometers broken or they just suck? on: June 08, 2012, 04:21:28 am
I had the same thing. It turned out it was the vibration of my computer on the same table.

Although only your fourth sensor has good readings, it is more likely that there is something with your code or connections.
Start with just one ADXL345 on the SPI bus, and try to get it right.

Hardware:
Is it connected to 3.3V ? Do you use 4-wire SPI mode ? How is the 'CS' connected ?

Software:
Do you use an example or library ? Which one ? Can you upload your code ? Are you sure the bytes are in the right order ?

Do you know there are links in the Accelerator section in the Playground : http://arduino.cc/playground/Main/InterfacingWithHardware#motion_accelerometer

I think you need to calibrate the offset anyway. As fas as I know all MEMS-based sensors need to be calibrated. Check the datasheet for "Offset Calibration".

In the end, they can get broken if they are hit too hard. But the ADXL345 can survive 10.000 g  shock ! That's more than many other sensors.
851  Using Arduino / Sensors / Re: unify reading from 2 x 3 axis compass on: June 02, 2012, 10:45:17 am
In such cases it is better to get a better sensor, instead of combining two.

Assuming you have already very good sensors, tilting one by 45 degrees and averaging the result might not increase the accuracy. The sensors should have the same accuracy all around.

To calculate the average, you can use the sensor-reading as a single vector. The amplitude is not important, but you need the degrees to the x,y and z axis. Simply substract 45 degrees from the second sensor and use the average.
852  Using Arduino / Motors, Mechanics, and Power / Re: Looking for beefier vibration motor on: June 01, 2012, 12:24:28 pm
The "Vibration Amplitude" is only 0.8 G for the 310-101. That's not a lot.

For a diameter of 12mm, there are motors with 1.7G: http://www.precisionmicrodrives.com/vibrating-vibrator-vibration-motors/pancake-shaftless-coin-vibration-motors

You could search for "pager motor" or "coin vibration motor" or "vibrating motor", but somehow I always end up with precisionmicrodrives.com.
853  Using Arduino / Sensors / Re: Gyro trouble on: May 31, 2012, 07:16:07 pm
linda89, the GY401 is ment to control a plane, it is not a sensor for a microcontroller.
You need to read it's output and process that trying to understand what the GY401 is doing.
If you want to have gyro information, perhaps you can buy a gyro sensor, and use that for the Arduino.
854  Using Arduino / Sensors / Re: MMA7455 g-force on: May 30, 2012, 02:31:20 pm
If someone is still reading this, I have just made a page for the MMA7455: http://arduino.cc/playground/Main/MMA7455
The 10-bits values are converted to normal 16-bit integers, and those are converted to floating point 'g'-forces.
855  Using Arduino / Installation & Troubleshooting / Re: Problem with Arduino Uno and ATMEGA328 on: May 28, 2012, 06:46:06 pm
I'm also pretty sure that your RAM usage is too big.

You can move strings to the code area with: Serial.println(F("Hello World"));
Do you have many arrays and buffers ?
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