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5761  Using Arduino / Installation & Troubleshooting / Re: How to connect an Arduino to the ADXL345 board on: March 20, 2012, 08:09:03 am
The datasheet shows max voltage ratings of 3.6V so you will need level shifting.

Do you have a raw chip or some kind of breakout board?

Looks like you have chosen the I2C (Wire library) interface.  Wire according to Figure 8 on the datasheet.
5762  Using Arduino / Sensors / Re: How to read register value from ADXL345 Eval board? on: March 20, 2012, 07:57:31 am
i change it to use SPI...and why still wont work??

See reply #3.  The accelerometer is NOT connected to the hardware SPI pins.  It is connected to A0-A3 (Pins 14-17).
5763  Using Arduino / Networking, Protocols, and Devices / Re: RCT DS3234 components needed? on: March 19, 2012, 10:27:59 pm
Yes, it looks like it will run fine on 5V.
5764  Using Arduino / Installation & Troubleshooting / Re: Power Problems? on: March 19, 2012, 10:20:43 pm
It would probably work if you could get it to fit and the pins are in the same order as the one already there.

Another choice would be to use an external regulated 5V supply and connect it directly to the 5V pin.  Most modern cellphone chargers have a mini- or micro-USB connector and would supply regulated 5V.
5765  Using Arduino / Installation & Troubleshooting / Re: Schematic error in Motor Shield? on: March 19, 2012, 12:27:42 pm
I guess the 'e' in the middle and the input leads extending across the body is supposed to signify "exclusive or".  I was able to find one other page on the net that uses that type of symbol:  it's used for a 4077N gate and without the output inversion for a 4070N gate:  http://electro-music.com/forum/topic-52066.html  It looks like the schematics there were generated by the same unnamed program.
5766  Using Arduino / Networking, Protocols, and Devices / Re: RCT DS3234 components needed? on: March 19, 2012, 12:00:07 pm
The battery and the bypass capacitor. 

You may have to also provide logic level shifting if your Arduino runs on 5V (as most do) and the clock chip can't stand 5V on inputs.  Look in the datasheet for the range of acceptable Vcc voltage and the range of acceptable input voltage.
5767  Using Arduino / Sensors / Re: How to read register value from ADXL345 Eval board? on: March 19, 2012, 11:56:56 am
Some of the functions can be adapted:
Code:
#define ACCEL_CS A0
#define ACCEL_SCK A1
#define ACCEL_DI A2
#define ACCEL_DO A3

#define SELECT_ACCEL()        digitalWrite(ACCEL_CS, LOW)
#define UNSELECT_ACCEL()    digitalWrite(ACCEL_CS, HIGH)

#define CLOCK_HIGH()         digitalWrite(ACCEL_SCK, HIGH)
#define CLOCK_LOW() digitalWrite(ACCEL_SCK, LOW)

char adxl345_read(char register_address){
char read_address=0x80 | register_address;
char register_value=0;

CLOCK_HIGH();
SELECT_ACCEL(); //Lower CS pin.

for(int bit=7; bit>=0; bit--){
CLOCK_LOW();
                digitalWrite(DI, read_address & (1<<bit));
delayMicroseconds(1);
CLOCK_HIGH();
delayMicroseconds(1);
}

for(int bit=7; bit>=0; bit--){
CLOCK_LOW();
delayMicroseconds(1);

CLOCK_HIGH();
delayMicroseconds(1);

register_value |= digitalRead(ADXL_DI)<<bit;
}

UNSELECT_ACCEL();

return register_value;
}
5768  Community / Bar Sport / Re: project developed on the basis of arduino on: March 19, 2012, 10:09:14 am
This will get you 80% of the way to your goal:

http://hacknmod.com/hack/top-40-arduino-projects-of-the-web/

(It was the second hit when I Googled for Arduino projects.  Perhaps Google can help you find another 10.)
5769  Using Arduino / Networking, Protocols, and Devices / Re: RCT DS3234 components needed? on: March 19, 2012, 10:06:28 am
See the "Typical Operating Circuit" on the very first page of the datasheet.  They show a bypass capacitor and a pull-up resistor on the INT/SQW pin.  You should also include a backup battery.

Under pin descriptions it says:

"4  VCC  DC Power Pin for Primary Power Supply. This pin should be decoupled using a 0.1μF to 1.0μF capacitor."

"5  INT/SQW  Active-Low Interrupt or Square-Wave Output. This open-drain pin requires an external pullup resistor. It can be left open if not used. This multifunction pin is determined by the state of the INTCN bit in the Control Register (0Eh). When INTCN is set to logic 0, this pin outputs a square wave and its frequency is determined by RS2 and RS1 bits. When INTCN is set to logic 1, then a match between the timekeeping registers and either of the alarm registers activates the INT/SQW pin (if the alarm is enabled). Because the INTCN bit is set to logic 1 when power is first applied, the pin defaults to an interrupt output with alarms disabled. The pullup voltage can be up to 5.5V, regardless of the voltage on VCC. If not used, this pin can be left unconnected."
5770  Using Arduino / Installation & Troubleshooting / Re: avrdude: usbdev_open Bootloading error. What's the solution? on: March 19, 2012, 09:58:32 am
If it doesn't depend on the target chip it is probably a fault in your OS setup.

Did you try rebooting your PC?

Do you have the proper USB drivers installed for your device?
5771  Using Arduino / Sensors / Re: How to read register value from ADXL345 Eval board? on: March 19, 2012, 09:50:25 am
The schematic (http://www.sparkfun.com/datasheets/Sensors/Accelerometer/ADXL345_Eval_Board-v11.pdf) shows the ADXL345 is connected to A0,A1,A2,and A3 and appears to use Soft SPI.  Nothing is connected to the I2C bus so the Wire library won't help you any. Perhaps you should start with the source code from the product page (http://www.sparkfun.com/products/9814)
5772  Using Arduino / Sensors / Re: How to read register value from ADXL345 Eval board? on: March 19, 2012, 07:34:52 am
In readFrom() you have an extra Wire.beginTransmission().
5773  Using Arduino / Programming Questions / Re: EEPROM on the ATMega328P on: March 19, 2012, 07:27:14 am
Unlike the Flash memory (used for your compiled binary) you can write to the EEPROM from your application.  And unlike the RAM it will stay set when the power is off.
5774  Using Arduino / Installation & Troubleshooting / Re: Power Problems? on: March 19, 2012, 07:18:45 am
Does this mean I need a new regulator? or is there something else which could have died?

From the schematic it looks like the 5V regulator is the most likely failure point. It's the only active component between Vin and +5 and it isn't used for USB power:

http://arduino.cc/en/uploads/Main/arduino-duemilanove-schematic.pdf

It should not be as hard to replace as most surface-mount components.
5775  Using Arduino / Programming Questions / Re: On startup, start loop at beginning of next minute on: March 18, 2012, 08:39:07 pm
Perhaps if you could provide the code you have now, the rest of the solution might present itself.
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