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13381  Forum 2005-2010 (read only) / Troubleshooting / Re: Stopping the power to a servo on: May 26, 2010, 12:40:49 pm
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That should solve my problems right?


That really depends of the specific servo you use and how much mechanical load you have on it's output arm. Many servos draw more then an amp at peak loads.

Lefty
13382  Forum 2005-2010 (read only) / Troubleshooting / Re: Reading Hall-sensor on: May 23, 2010, 10:24:51 am
It could also be that the sensor is designed to not respond to fast changes, do you have a data sheet for the sensor?

Lefty
13383  Forum 2005-2010 (read only) / Troubleshooting / Re: voltage drop? on: May 22, 2010, 02:52:56 pm
Standard 9 volt batteries are a poor choice for powering an Arduino board. They have low current capacity and are probably the highest cost battery per MAH ratings. A DC 'wall wart' power supply (9vdc @ 1amp) would be a real cost saver over time, but don't get it at radio shack as they are vastly priced there, on line is your friend.

 If you must go with non-rechargable batteries you would be much better off using AA size batteries, using  6-8 of them in a series cell arrangment with a suitable batter holder.

Lefty
13384  Forum 2005-2010 (read only) / Troubleshooting / Re: Fried Duemilanove... on: May 14, 2010, 09:46:18 pm
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Should I be worried?

No, not necessarily. It all depends on how much current you want to draw from external components wired to the Arduino. The basic Arduino board probably draws less then 75ma, so the regulator only has to dissipate around 1/2 watt for the basic board. If you try and draw 700ma of current for external loads, then it would be much better if you could find a 8 volt source. Most all linear regulators have automatic over current and over temperature protection, they just shutdown until the overload condition is removed.

Lefty
13385  Forum 2005-2010 (read only) / Troubleshooting / Re: Fried Duemilanove... on: May 09, 2010, 07:11:46 pm
Am I correct in plugging the positive into the arduino's VIN pin and the ground into the Arduino's Gnd Pin?

Yes, that will work, but it's better to utilize the external power jack as you then get the added protection of an on-baord series diode to protect from reverse polarity.
Also what is the GND pin on the other side (next to pin 13)? Just another place to ground?  Yes, it's just another ground pin
Thanks again.

Lefty
13386  Forum 2005-2010 (read only) / Troubleshooting / Re: Fried Duemilanove... on: May 09, 2010, 06:34:01 pm
Before you buy a replacement AVR chip (with bootloader installed) you had better test if your FTDI USB serial chip is functioning OK. place a wire from a ground pin to the reset pin. Then place a wire jumper between pins 0 and pin 1. Now plug in your USB cable and see if the PC 'sees' the USB connection. If it does, open up the Arduion IDE, select the proper comm port number. Then open up the serial monitor, anything you type and send from the output window should echo back on the receive window. If that is all OK then go ahead and replace the AVR chip, if not your probably better to just get a new board as the FTDI chip is very difficult to remove and replace.

Lefty
13387  Forum 2005-2010 (read only) / Troubleshooting / Re: standalone working but not working properly on: May 13, 2010, 11:06:50 am
Did you wire a pull-up resistor to the reset pin?

Lefty
13388  Forum 2005-2010 (read only) / Troubleshooting / Re: avrdude     ....     :( on: May 10, 2010, 04:26:25 pm
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I don't understand what you you mean by test the FTDI chip..
on the link you sent me they talk about installing the FDTI driver.. it that what you mean??

The FTDI chip is the USB serial converter chip on the Arduino board that allows communication to and from the AVR processor to the Arduino IDE software on your PC. By performing the FTDI loopback test you are proving that there is no problem with the PC, the USB driver software, the USB hardware and cable. The error you are getting from AVRDUDE just means that there is no communications from the AVR chip to the PC. The FTDI test will 'half split' the problem from being caused the AVR processor chip or not.

Lefty
13389  Forum 2005-2010 (read only) / Troubleshooting / Re: Low power on digital 1 to 12? on: May 09, 2010, 01:39:31 pm
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0 seems to always be on high on the Seeeduino.

Well the high on pin 0 would be coming from the serial data output (high = idle serial data, i.e. stop condition) from the on board FTDI USB serial convertor chip not from the pin 0 pin itself as it's the serial input for the bootloader program.

Lefty
13390  Forum 2005-2010 (read only) / Troubleshooting / Re: Low power on digital 1 to 12? on: May 09, 2010, 12:01:23 pm
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Pin 13 is pre-initialised by the bootloader as an output, so it can flash the LED at you.
The 'C' preamble (what goes on before "main" runs) doesn't affect any of the I/O pins, so this this stays as an output, unless you later change the mode in "setup" or "loop".

I've never looked into that the bootloader leaves pin 13 in output mode when jumping to the sketch. I would have thought that it would be better for it to return the pin to the default input mode, but I guess as long as it's documented some where (is it, or does one have to read the bootloader source to tell?) it can be lived with.  smiley-wink Does it leave pin 1 (serial output pin) in the output mode also?

Lefty
13391  Forum 2005-2010 (read only) / Troubleshooting / Re: Low power on digital 1 to 12? on: May 09, 2010, 09:05:01 am
As already stated, you have forgotten to have pinMode commands that setup up pins to be inputs or output prior to doing digitalWrite commands:

http://arduino.cc/en/Reference/PinMode

Lefty
13392  Forum 2005-2010 (read only) / Troubleshooting / Re: High(4.7V) Voltage in an Analog Input on: May 05, 2010, 12:51:34 pm
If you disconnect the signal wire from analog pin 0 and then measure the sensor wire, what voltage do you read? If it's still +4.7 then it would point to a sensor problem, no?

Lefty
13393  Forum 2005-2010 (read only) / Troubleshooting / Re: Analog inputs are linked for no good reason on: May 04, 2010, 02:27:06 pm
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Does anyone have any idea why this would happen or how to stop it?

If there is nothing wired to a analog input pin, it will be in a 'floating' condition and just read noise and it's value can be effected by adjacent analog input pins that are wired and being used. There is no real problem with this, but you could wire pull-down resistors to quite them down, or program them to be digital output pins.

Now if the pins are wired to something and you are seeing values change based on other inputs then that is something else. I would have to see the external wiring in that event.

Lefty
13394  Forum 2005-2010 (read only) / Troubleshooting / Re: Arduino Reading vs. Multimeter Inconsistency on: May 04, 2010, 10:13:10 pm
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The math for voltage divider:
56000/156000 = 0.358974358974359
5/0.358974358974359 = 13.92857142857143
13.92857142857143/1023 = 0.0136154168412233

One thing about the math, the resistors all have a accuracy tolerance and therefore you can't calculate the expected voltage just from their stamped value. One would have to measure them with an known accurate ohm meter and go from there.

As far as how to deal with two meters and one Arduino A/D measurements. Old Chinese saying: Man with one watch always knows the time, man with two watches never quite sure  smiley-wink

As the Arduino A/D is just 10bits and it's published accuracy is +/- 2 bits, I would trust your meters more then the Arduino value. Meters themselves will have a accuracy error of some value and unless calibrated recently one really doesn't know for sure. One could have some stable reference voltage to check meters with. In the old days we use to use a mercury battery cell as a reference as they had a good stability value.

Anyway welcome to the world on instrumentation where we have so many watches we never really know what time it is.  smiley-wink

Lefty
13395  Forum 2005-2010 (read only) / Troubleshooting / Re: Problems with Mosfet as solenoid switch on: May 03, 2010, 05:56:11 pm
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What could I do indirectly?

If you don't use a logic level mosfet, then you will require a npn switching transistor that the arduino can drive via it's base and the npn collector resistor would wire to the +19v supply voltage. Then as the Arduino switches the npn converts it to a 0-19vdc gate drive signal. You also require a base series resistor from the arduino pin to the npn. This setup will introduce a logic inversion such that an arduino high output will turn off the mosfet and a low will turn it on.

Me, I only search out and buy logic level mosfets, my favorite.

Here is a nice high power N channel logic level mosfet that a user found recently:

http://www.rapidonline.com/netalogue/specs/47-0554.pdf

Lefty

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