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5701  Using Arduino / Programming Questions / Re: Why the watchdog at Arduino works wrong? on: April 12, 2012, 12:36:51 pm
The watchdog timer works fine on my Arduino UNO R2 with the latest bootloader from Arduino 1.0.  Have you tried burning a fresh bootloader?

Code:
//  Watchdog Timer Example
#include <avr/wdt.h>

unsigned long ToggleDelay;  //  When this delay grows to longer than the WDT interval the WDT resets the Arduino

const int LEDpin = 13;

void toggle_led()
{
  digitalWrite(LEDpin, !digitalRead(LEDpin));
}

void setup()
{
  wdt_disable();
  ToggleDelay = 1;   // Start with a very short delay
  pinMode(LEDpin, OUTPUT);
  wdt_enable(WDTO_250MS);  // Set watchdog to 1/4 second
}

void loop()
{
  wdt_reset();
  toggle_led();   // Blinking goes slower and slower until the WDT causes reset, then starts over.
  delay(ToggleDelay);
  ToggleDelay += 5;   // Increase the delay by 5 milliseconds.
}
5702  Using Arduino / Installation & Troubleshooting / Re: uploading sketches using an ISP on: April 12, 2012, 11:44:31 am
Sounds like your chip is not set up to use a 16 MHz crystal.  Do you have a 16 MHz crystal attached to it?

Try adding your programming to the IDE by creating a 'programmers.txt' file in the 'hardware' folder of your sketch folder.
5703  Using Arduino / Microcontrollers / Re: requirements and limits of 8Mhz 3.3v on: April 12, 2012, 11:36:31 am
If you burn an 8MHz bootloader on the chip you can upload sketches just like any other Arduino.  The voltage doesn't matter as long as it is high enough for 8 MHz operation.  You can run at 10 MHz on 2.7 V but 1.8V is only good for 4 MHz so something like 2.4V for 8 MHz?  Anything between 2.4 V and 6.0 V should work.

Arduino 1.0 doesn't seem to come with an 8 MHz version of the optiboot bootloader.  You may have to re-compile the optiboot bootloader for 8 MHz if you really need that.
5704  Using Arduino / Motors, Mechanics, and Power / Re: leverage formula?? on: April 10, 2012, 08:14:10 pm
If your servo torque is measured in kilogram centimeters you need 0.126 kg * 100 cm = 12.6 kg.cm

To get ounce-inches you divide by 0.0720077887081 so about 175 oz.in

You should also account for the mass of the arm.  Figure average lever arm for the arm is 50 cm.

You may need more torque to accelerate the arm at a reasonable rate.
5705  Using Arduino / Networking, Protocols, and Devices / Re: Still struggling to send data over UDP on: April 10, 2012, 08:06:27 pm
If you are using Arduino 1.0 and want to specify the IP address you also have to specify the Default Gateway and DNS Server addresses before you specify the Subnet Mask.

I think you are passing the subnet mask as the DNS Server address.

http://arduino.cc/en/Reference/EthernetBegin
5706  Using Arduino / Networking, Protocols, and Devices / Re: Problem connecting to TI ADS1212P via SPI on: April 10, 2012, 05:26:39 pm
If you have SDOUT connected to MISO (Master In/Slave Out) you will have to set the SDL bit of the command register to 1.  The default is to use the same pin (SDIO) for Input and output.
5707  Using Arduino / General Electronics / Re: ATtiny13A for controlling a vibrator - Datasheet Question on: April 10, 2012, 08:44:57 am
I agree with your reading of the graph.  When running off 1.8 V the output pins can supply 1.6 V at 3 mA or 1.4 V at 5 mA.

Switching voltage with a transistor might be the solution but it is my understanding that a transistor has a voltage drop across it much like a diode.  If you r power supply is 1.8 V this voltage drop might be significant. Maybe someone with real electronics training can help.
5708  Using Arduino / Sensors / Re: Magnetic sensor by Sure Electronics DC-SS503 on: April 10, 2012, 08:34:53 am
Couldn't find any application notes on the subject.  Perhaps you should hook one up and see what signal you get when you drive a car over it.
5709  Using Arduino / Installation & Troubleshooting / Re: Bootloader installation problems - mega2560 - ARVISP mkII on: April 10, 2012, 08:16:56 am
> I tried whatever comes loaded on the R3 Arduinos (any idea what that is?) and it timed out properly but never came back after the timeout. 

The test code works fine for me on my Arduino UNO R2. smiley-sad


> I have read that this is the main problem with the Arduino and the watchdog circuit.  It seems
> that on reset (by the WDT) the timeout is changed to 15mS and enabled so the bootloader never
> gets a chance to make it to my setup() code before retriggering.  That appeared to be what was
> happening to me.

I had read that the WDT doesn't get disabled after a timeout and that if the bootloader took too long you could get into a WDT loop but I had not read that the WDT interval gets reset to 15ms.  I just burned the Arduino 1.0 UNO bootloader into my UNO R2 and the WDT test sketch still works fine.


> On a related matter, the Arduino IDE ships with several bootloaders (STK500V?, Optiboot, etc). 
> How do you tell it which one to use or does it pick based on the particular microprocessor
> you have selected under "Tools->Board"?

Yes.  The 'boards.txt' files have a pointer to the bootloader for each type of board.  You can put your own 'boards.txt' file in the 'hardware' folder inside your sketch folder and the IDE will pick that up next time you start it.


> Is there anyway to find out which bootloader is programmed in the chip?

Not really.  The only way I know of to be sure is to burn a fresh bootloader.
5710  Using Arduino / Project Guidance / Re: Complete Noob, need advice on: April 09, 2012, 10:02:14 pm
You will need an Ethernet cable between the Ethernet Shield and an Ethernet port on a router connected to the Internet.  Power can be supplied over the Ethernet cable if you get the optional Power Over Ethernet (POE) module on your Ethernet Shield and your router can supply POE.  Otherwise you should probably get 9V 'wall wart' power supply that can plug into the power jack on the Arduino.

Look at the Files->Examples->Ethernet->TwitterClient example.
5711  Using Arduino / Installation & Troubleshooting / Re: 'digitalwrite' was not declared in this scope on: April 09, 2012, 09:55:02 pm
It's spelled "digitalWrite".  Identifiers are case sensitive.
5712  Using Arduino / Installation & Troubleshooting / Re: Bootloader installation problems - mega2560 - ARVISP mkII on: April 09, 2012, 09:48:08 pm
The Mega has too much memory to run a bootloader that speaks STK500V1.  You need an STK500V2 bootloader.

How long a WDT interval do you need?  As long as the bootloader gives control to setup() before the WDT times out again you should not have a problem with the bootloader.

Have you tried the WDT with the standard bootloader?

Here is a WDT test sketch.  It blinks slower and slower until the toggle delay grows beyond the WDT limit. At that point the WDT times out and resets the system.
Code:
#include <avr/wdt.h>

unsigned long ToggleDelay;

const int LEDpin = 13;

void toggle_led()
{
  digitalWrite(LEDpin, !digitalRead(LEDpin));
}

void setup()
{
  wdt_disable();
  ToggleDelay = 1;
  pinMode(LEDpin, OUTPUT);
  wdt_enable(WDTO_250MS);  // Set watchdog to 1/4 second
}

void loop()
{
  wdt_reset();
  toggle_led();
  delay(ToggleDelay);
  ToggleDelay += 5;
}
5713  Using Arduino / Storage / Re: SD card pins on Arduino Mega problem on: April 09, 2012, 09:37:21 pm
The SD card uses the SPI interface pins (50-53?)  Perhaps you can get around the need for a true "Ground" pin next to six digital pins by using a 7th digital pin set to "LOW" as a "Ground".  Should work as long as the LCD uses less than 40 mA.
5714  Using Arduino / Project Guidance / Re: Person tracking robot guidance system on: April 08, 2012, 02:39:46 pm
A few weeks ago the Ben Heck Show was about building a rolling luggage robot that would follow its owner.

http://revision3.com/tbhs/robotluggage
5715  Using Arduino / Project Guidance / Re: Crazy Erratic servo operation on: April 05, 2012, 12:54:50 pm
You must have the Arduino and Servo(s) share a Ground so that's not the problem.

The code looks fine assuming your pots are wired correctly: +5, A0/A5, Gnd.

My guess would be a wiring error of some kind.  The servos should have +Power on Red, -Power and Arduino Ground on Black and Signal on White (or Yellow).
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