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10561  Using Arduino / Project Guidance / Re: How to use millis function to turn led on for 5s then turn it off indefinitely? on: February 27, 2011, 12:19:48 pm
Ahh... one problem..... I dont want to use the delay function i want to use the Millis function? Any ideas?
So we have circled around again to the AWOL suggestion:

Have a look at the blink without delay example.
10562  Using Arduino / Audio / Re: Simple Passive Sonar on: February 27, 2011, 12:04:56 pm
do not know if this is at all possible, but I was imagining that when any one of the 3 or 4 digital inputs switched to a high state it would start a timer and see how long before the other inputs switched to high.

It's pretty straight forward. You can utilize the arduino micros() or millis() commands (depending on your time resolution requirements) to take a 'snapshot' of either these two free running timer variables. You save the present count in a variable when a 'start' change is read on a input pin and then when another pin changes you again read the time function and compare it to the saved 'start' variable, the difference in time is how long it took for the event to happen sense it was started. You need to deal with if a pulse never returns, so your code would need to check on a time out value to give up waiting for a input pin that may never change.

PS: "Passive Sonar" is really a much different animal and you are probably misusing the term. Active sonar is where you send a ultrasonic pulse and wait for a return pulse. Passive sonar is more like simply listening with a microphone to see what sounds may be out there. In Navy use, active sonar can give the 'enemy' the knowledge that you are out there by the pulses you are transmitting, where passive sonar does not give your location away.


10563  Using Arduino / Sensors / Re: Calibrated Thermistor for Cooking on: February 27, 2011, 11:46:39 am
In context of using your data with arduino sketches is there value in having so many significant digits in the constants listed? From the Arduino reference for float variables:

Floats have only 6-7 decimal digits of precision. That means the total number of digits, not the number to the right of the decimal point. Unlike other platforms, where you can get more precision by using a double (e.g. up to 15 digits), on the Arduino, double is the same size as float.

10564  Using Arduino / Microcontrollers / Re: Arduino faster than the Mega? on: February 27, 2011, 11:41:35 am
Arduino will always provide a DIP version of the basic Arduino board

(as long as ATMEL keeps making the processors)


Thank you for that information. That is a wise decision on your part.  smiley-wink

10565  Using Arduino / Motors, Mechanics, and Power / Re: 4 dc motors and 4 rc servos? on: February 27, 2011, 11:35:42 am

?, Is that your real name? Or text speak for something? Learning to program will help you to be more accurate and specific in your written communications.  smiley-grin

10566  Using Arduino / Motors, Mechanics, and Power / Re: Indicating weak batteries on: February 27, 2011, 11:19:18 am
There are several methods of measuring battery voltage and predicting remaining battery charge. However a lot of details need to be worked out and they are dependent of the actual battery chemistry being used, the batteries nominal voltage output range, batteries MAH rating, and other details. If you can better describe your power system in detail perhaps we can suggest effective power management methods you might include.

10567  Using Arduino / Microcontrollers / Re: is there any other way to burn bootloader? on: February 27, 2011, 11:14:24 am
No, it's a chicken and egg kind of thing. A bootloader is the first chip code that has to be loaded as there is no existing bootloader on the chip to allow serial program loading.

An ISP programmer can load either bootloader code or normal code, but a running bootloader can only load normal programs onto a chip. However with  the proper sketch (ArduinoISP) running on a standard arduino board that board can then emulate being a ISP programmer and load bootloaders into other boards or even blank AVR chips mounted on a breadboard.

10568  Using Arduino / Project Guidance / Re: Measuring the power produced by a solar panel on: February 27, 2011, 11:03:43 am
As already stated you have the current sensing resistor on the wrong lead of the solar panel, it needs to be on the ground lead side as I had clearly explained originally.

 What you really need is an accurate system drawing made up to at least validate all the power and ground leads are properly wired to all the system components to see if the concept can be made to work.

Current measurement of what's happening to the system battery will be a little trickier as the current may be flowing into or out of the battery at different times. But I suggest you first get the system documentation up to snuff and get your basic solar panel measurements working.

10569  Using Arduino / Interfacing w/ Software on the Computer / Re: external 5V at Vin pin, and USB connection - UNO board on: February 27, 2011, 01:39:11 am
The schematic helps a lot, you got a lot of stuff going on there. Now a problem is you are routing +5vdc shield voltage (Vcc) to the Arduino uno via the shield's Vin pin? That won't work, the Vin pin on the Uno has to have at least 7 vdc applied to it to power the input of the Uno's 5vdc regulator.

 I thought you might to powering the uno board by wiring the shields vcc to the +5vdc pin on the shield connector, thus then having the two regulator outputs tied together problem I mentioned, if you were also routing voltage via the Vin pin, which your aren't.

This is all giving me a headache.  smiley-grin Anyway I still don't see a perfect way to power the system and still be able to utilize USB power when you wish. But what you have right now is flawed because the uno's regulator's input needs to be 7vdc or higher to operate correctly.

10570  Using Arduino / Project Guidance / Re: Question about shilds on: February 27, 2011, 01:03:34 am
would that work is there a limit?

Well not a designed in limit. However one can't use shields that use any of the same I/O pins. One can't stack shields such that they in total require more +5vdc current then the Arduino board can safety supply. One can't stack shields is the lower shield has extra tall components that mechanically interfere with a top shield board. One can't stack on top of a shield that has connectors or controls that need top surface access, etc, etc.

So it's not a simple question.

10571  Community / Bar Sport / Re: What else offer an Arduino MEGA beside the big amount of ports? on: February 27, 2011, 12:59:25 am

it has more pins which can do PWM, than the arduino, right?

From the reference:

On most Arduino boards (those with the ATmega168 or ATmega328), this function works on pins 3, 5, 6, 9, 10, and 11. On the Arduino Mega, it works on pins 2 through 13. Older Arduino boards with an ATmega8 only support analogWrite() on pins 9, 10, and 11. You do not need to call pinMode() to set the pin as an output before calling analogWrite().

More timers means more PWM pins avalible.
10572  Using Arduino / Project Guidance / Re: 10x10 LED grid on: February 27, 2011, 12:26:41 am
In a 5x5x5 led cube I build I really like the use of the 16 bit constant current output pins shift regesters.

The use of programmable constant current output pins solve a big design hurdle as led brightness becomes independent of the scanning rate you use. Just one resistor needed for each 18 bit device so current limiting becomes adjustable and minimizes component count.

Anyway one of these devices would handle the 10 row common connected leds (requiring only 3 arduino output pins), then you just need 10 arduino output pins to drive the common column led connections. Use the MsTimer2 library to setup up a scanning interrupt routine and it becomes a pretty straight forward project.

10573  Using Arduino / General Electronics / Re: Please check my circuit for errors.. on: February 27, 2011, 12:12:52 am
The cap helps keep noise from the reference and therefore is often used to get cleaner analog readings.

When using one of the INTERNAL options AREF is actually connected to this internal reference, if it is also connected to say 5v you have 5v->1.1v (or whatever is selected) which is bad.

You can connect Vs to AREF but have to be very careful never to use an INTERNAL reference.


Actually the Arduino reference has instructions on wiring a series resistor between the Aref pin and any external voltage reference being used. That would prevent damaging current level flows in case of misuse of the analog reference command.

10574  Using Arduino / Microcontrollers / Re: Arduino faster than the Mega? on: February 27, 2011, 12:07:15 am
Does anyone know if the Arduino 'company' plans on offering both the dip and smd versions of the Uno in the future?

 It would a real shame if they didn't continue to offer a dip mounted version as that takes away some of the flexiblity and ease of repair, both important features in my opinion.

10575  Using Arduino / Installation & Troubleshooting / Re: No green light on: February 27, 2011, 12:01:32 am
The relentless march of the Ebay knock-offs.......  smiley-wink

Blue is the new Green
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