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91  International / Portugues / Re: Sensor de distância HC SR04 (programação em Milimetros (mm)) on: May 10, 2013, 12:11:34 pm
Tenho tido erros com sensorses, porque a biblioteca deles usa o delay, lembra que a velocidade do som varia com a densidade do ar que varia com a temperatura, a velocidade da biblioteca esta setada para o ar a 25°C não sei se e esse o problema, mas vale a pena verificar se vc precisa mesmo dessa precisão.

Outra coisa apesar de dar um trabalho homérico e reescrever a lib sem o uso de delays.

Para um SR04, esta diferença de velocidade do som é ABSURDAMENTE IRRELEVANTE, pois qualquer que seja a pressão atmosférica, temperatura, ou qqr outro fator ambiental, causará um impacto muito menor que a precisão do SR04.

Qualquer pessoa para quem estes fatores são decisivos para uma medida, primeiramente não estaria usando um SR04, segundo saberia converter de cm para mm, terceiro saberia a diferença entre precisão de medida e unidade de medida.

Eu diria que o uso de delay() em uma biblioteca como esta é absolutamente necessário. Reescrever é possível? Talvez, com um trabalho homérico e hercúleo, mas é realmente necessário? NÃO. A náo ser que você esteja usando um arduino para aplicações em RealTime, deixe os delay() onde estão e pronto.

Acho que o mais importante aqui é, do que eu quero falar é: aprendar primeiro a usar as ferramentas que você tem. Aprenda o básico primeiro, o essencial, para somente então começar a pensar em algo melhor ou mais avançado. De nada adianta dar uma Ferrari para quem não sabe dirigir nem um Fiat 147.
92  Using Arduino / Project Guidance / Re: Arduino version for permanent installation on: May 10, 2013, 12:05:04 pm
With the UNO, you can get up to 32kb of flash only if you lose the bootloader. Otherwise you get 31.5kb.

The Arduino MEGA 2560  has 256kb of flash memory, which is 4x more what you need.

Another option is to use clones based on the Atmega1284 or 1284P, such as the Bobduino. It has 128kb of flash memory + 16kb of RAM: http://arduino.cc/forum/index.php/topic,61126.msg501759.html#msg501759
93  Using Arduino / General Electronics / Re: Where do you buy your components? on: May 09, 2013, 01:26:39 pm
What electronics suppliers do you guys use?
(...)
When I am done testing on the proto breadboard, where is a good place to have custom boards done?

I buy lots of components from www.dx.com (DealExtreme) They don't have everything I need, but their prices is unbeatable. The delivery time, however, can vary from 2 to 6 weeks. I bought a pack of 4,000 resistor (1/4W) of varied values from them. I've also bought packages of capacitors, diodes, crystals, connectors, etc. Only when I need something very specific to my needs, in low quantities, I go to local stores.

For making PCBs, this is everyone's (or almost everyone) favorite: http://imall.iteadstudio.com/open-pcb/pcb-prototyping.html

I've ordered from them in the past. Got 12 boards for the price of 10.
94  Using Arduino / Microcontrollers / Re: How to reduce Arduino Micro/Leonardo bootup time? on: May 09, 2013, 11:29:15 am
I used a regular Uno R3 running ArduinoISP sketch to burn optiboot bootloader in one of them to set the fuses.  I then load ArduionoISP sketch into this chip and use to burn bootloader into the other blank chip, also to set fuses.

Using that same UNO R3 with the ArduinoISP sketch, you may be able to update the bootloader on the Leonardo.

In the IDE, just make sure you select the Leonardo as Board and ArduinoISP as the programmer.

95  Community / Bar Sport / Re: how to impress a girl with arduino! on: May 09, 2013, 11:04:56 am
i made a huge "I love You" sign (...)

I hope that wasn't a first date!
96  Community / Bar Sport / Re: Fundawear?? on: May 09, 2013, 11:02:49 am
Imagine the consequences if someone hacks into those devices.

97  Community / Bar Sport / Re: joke on: May 09, 2013, 10:59:27 am
Ancient Chinese saying:
Man standing in corner with hands in pockets, not feeling crazy... feeling nuts.
98  Community / Bar Sport / Re: My camera discontinued on: May 09, 2013, 10:10:18 am
I read that news a few days ago too. I follow several Photography channels on Google Currents.

The advantage of this news for you is that this model of the Hasselblad will have their prices skyrocketed in a few months/years. They'll become a desired collectors item. If I were you I'd hold on to mine and keep it in working state. Who knows, maybe in a few years you might be able to sell it for a several thousand dollars.

About a year ago I sold a Canon EOS 500n (35mm, very basic, entry-level SLR camera) for about US$ 350. It was in  practically New In box, with original manuals, box, lenses kit, 2 new unopened 35mm film rolls (FUJI), UV filter, etc. I inherited it from my uncle, who I believe didn't run more than 2 rolls of film through it.

I still have 4 very old 35mm cameras: an Olympus Trip 35, a very old Kodak, a Minolta (SLR) and a Pentax (SLR) [can't remember the models]. I know that my Pentax has seen a substantial raise in market value in the last few years.

My day-by-day cameras however are a Canon A620 (it stays in the car all the time) and a Nikon D7000.
99  Using Arduino / Project Guidance / Re: Is this project possible? on: May 09, 2013, 09:48:16 am
a. How will the temperature be measured? -- honestly i don't know yet what kind of hardware to use smiley-confuse ..

Take a look at this:  https://www.sparkfun.com/products/10988

Quote
btw, your work on homemade stackable shield is impressive.

thanks!
100  Using Arduino / General Electronics / Re: Arduino Powers on With Power Applied to Input Pin on: May 09, 2013, 06:49:03 am
all of the inputs running through 7805 voltage regulators to bring the power down to 5V.

What you should be doing is using 5.1V Zener dioes, along with a circuit that only takes signals to the Arduino's input pins if there is power applied to the arduino (a simple NPN transistor can take care of that) .  Not only 7805 are way too expensive for this simple task, but it adds complexity to the circuit and waste power.
101  International / Portugues / Re: Sensor de distância HC SR04 (programação em Milimetros (mm)) on: May 09, 2013, 06:43:08 am
Vai ver o seu sensor é americano (ou voltado para o mercado americano) e só funciona com polegadas.  smiley-yell smiley-yell smiley-yell
102  Using Arduino / Project Guidance / Re: Is this project possible? on: May 08, 2013, 06:58:51 am
Quite possible and not one of the hardest do to.
IMHO, difficulty level is about 4 (on a scale 1 [very easy] -10 [extremely hard]).

You'll have to make a few choices:

a) How will the temperature be measured?

  - Thermistor (analog)
     Very cheap, easy to program (if you have the formulae), very easy to build a circuit for, but it is also less precise than the digital methods

 - LM335 or similar (analog)
   precise, easy to circuit

 - LM35 (digital)
   very precise, but a bit harder to program, easy to circuit, more expensive

  - specialized IC, like DS1624 (digital)
  most precise, slow temp change, most expensive of these methods, a bit harder to circuit, but easier to program, since there are readily available libraries for it (I've published one here on the forums... check my sig)

  - there are certainly other methods, but these are the more common ones

b) How will you connect to the internet?

  Your options are, basically, through ethernet ( $ ), wi-fi ($$) and 3G ($$$).

For everything you need to do (read temp, send e-mail, etc), there are probably code samples on the internet and possibly here are the forums. So your task might be resumed to build the circuit, put all the sample code together and test.
103  International / Portugues / Re: Sensor de distância HC SR04 (programação) on: May 07, 2013, 03:24:28 pm
Bubulindo... posso estar falando merda... mas se eu tenho 1 cm e multiplico por 10, consequentemente, digo que 1 cm * 10 partes = 10 cm;
Já que 1 cm = 10 mm, então seria, 1 cm DIVIDO por 10 partes, isso significa que vou dividir meu 1 cm em 10 pequenas partes, resultando em milímetros.

^^

Caramba! Eu realmente acho que este tópico merece um prêmio.

cara, acho que Arduino não é para você.

Vamos relembrar da 4ª série do ensino elementar?

1cm = 10mm
Portanto 1cm = 1mm x 10

Se você tem uma medida em cm, multiplique-a por 10 e terá a mesma medida em mm. Você não está multiplicando a coisa sendo medida, mas mudando a unidade do valor observado. É realmente complicado demais?
104  Topics / Device Hacking / Re: UNO as a HID compliant joystick? on: May 07, 2013, 12:28:30 pm
This is easier to achieve with a Leonardo or a USB Host shield.

The UNO itself can't do it, because the Atmega328P on it doesn't talk directly to the USB port on a computer. It needs something in between, be it the Atmega8u2 or Atmega16u2 on it or the USB host shield.

If you reprogram the Atmega8u2 (or 16u2) on your UNO, you'll lose the feature of uploading sketches through the UNO's USB port.
105  Using Arduino / Microcontrollers / Re: Speeding up the compiler on: May 07, 2013, 09:30:44 am
There used to be an issue with having Bluetooth enabled and the rxtxSerial DLL - does anyone know if that one is fixed?

No, not yet, at least in the official Arduino IDE up to 1.0.4. The unnoficial Enhanced IDE, made by Eried, has had that bug fixed for quite some time now.  That bug, however, doesn't make the compile process longer, but it makes everything that has to do with serial ports enumeration a lot slower.

I wonder when they'll be brave enough to fix that.

During a "Check" or "Compile" sketch, only a copy of the sketch is saved to a temp folder, where the compiler/linker/avrdude will work from. The real file of the sketch isn't saved during either of those actions.
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