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226  Topics / Product Design / Re: Atmega 328 and TLC5940 routing on: April 01, 2013, 01:14:24 pm

The bypass caps are there (2 x 10uF caps): one is in the output of the 7805 voltage regulator. In all the pictures where the breadboard appears with the 7805, the bypass cap for the Atmega328 is the upper rightmost cap. Note that the 7805 also requires an input capacitor and it is also there, to the left of the other capacitor, also 10uF.

227  Using Arduino / General Electronics / Re: Anyone know a strong P channel MOSFET (about 40v, 1A, logic level) ? on: April 01, 2013, 09:43:32 am
How about this.

Isn't the IRF520 a N-channel MOSFET ? I believe the OP needs a P-channel.
228  Using Arduino / General Electronics / Re: Anyone know a strong P channel MOSFET (about 40v, 1A, logic level) ? on: April 01, 2013, 09:37:49 am
I'd say nearly all of them. It'd be more trouble to find one than CAN'T handle that than one that can.

1A at 40V is nothing for a MOSFET, provided they have a cooling rib.

Here's a brief list from Vishay:
229  Community / Bar Sport / Re: Won't be soldering these.... on: April 01, 2013, 07:40:11 am
Patents are almost nothing. (...)

I partially disagree. Patents are very relevant... just ask the Samsung and Apple lawyers!

I have been battling with that for the last 2 weeks: I didn't invent anything, but I found a use for something that no one had thought before, and I adapted that idea, improving it  A LOT. The new use is eligible for a patent, and there is nothing in the market like it. It has become a really "marketable" (is there such word?) product, and now I need an investor. All the investors I've seeked require that I have a patent, so I am applying for one (with is gonna leave me US$ 2,000 poorer).
230  Community / Bar Sport / Re: Won't be soldering these.... on: April 01, 2013, 06:59:03 am

- That means that hardware will also be affected by viruses (or viri, as the proper latin dictates).

- You won't be buying NPN or PNP transistors, but rather ACA and TGT transistors (remember the letters in the RNA sequence, AT, CG)?

Seriously now,  I honestly believe that is a few decades from becoming a reality in the market. Probably what follows is that Stanford applies for a patent for the idea or the proccess, so that noone can explore that possibility in the future without paying huge royalties to Stanford or the scientists.

IBM has done the above several times. I the 90's I was a subscriber of PC World and remember reading about the "new" technologies in data transmission that would change forever the way chips are built. Quantum and optical CPUs were the core of the idea. 20+ years after that and we still have none of those.
231  Topics / Product Design / Re: Atmega 328 and TLC5940 routing on: April 01, 2013, 06:42:38 am
I prefer DipTrace, and I've been using it for the last year for my personal projects. I know Eagle might be more powerful and has a gigantic user base, but I like DipTrace better. The free version is great and should be enough even for more advanced hobbists.

Back on topic: ditch that layout, since there are several problems with it:
- the crystal is too far from the 328
- there are sharp corners in the traces. Never, NEVER route traces with 90º angles.
- there is no bypass capacitors for either chip
- it is good practice to use every space left in the board (in its signal side) for a copper pour linked to the ground net.

If you decide to go ahead and use that circuit anyway, that one is easier done with a perfboard, rather than etched. Make use you use DIP sockets, instead of soldering the chips directly to the board.
232  Using Arduino / Microcontrollers / Re: DS1307 Heats up on the soldered board on: March 27, 2013, 11:26:15 am
Try placing a 100 ~200 ohms resistor between the Atmega's VCC and the DS1307.

233  Using Arduino / Motors, Mechanics, and Power / Re: DC motor speed regulator using Arduino Uno on: March 27, 2013, 09:57:11 am
What is the motor driver IC you are using?

If it has an EN pin, simply use PWM signal to pulse the EN pin. This will effectively control the speed of the motor. I am using this technique with a L293D in an Arduino shield I built myself.

Another option is to have an adjustable voltage regulator (such as a LM317T) powering the motors, and have the Arduino control the variable resistance of the ADJ pin in the regulator. this can be done in two ways:

1) simply use a digital potentiometer (5Kohm, 8bits : enough for up to 20V output of the LM317 in 256 steps)

2) use a 74HC595 to control 8 resistors in a voltage divider that will be connected to the ADJ pin of the LM317T. I saw this method recently on a website, but never actually used it: too much work!

234  Using Arduino / Motors, Mechanics, and Power / Re: H-Bridge to provide about 150A at 18V? on: March 27, 2013, 09:35:16 am
To complement my previous answer:

235  Using Arduino / Motors, Mechanics, and Power / Re: H-Bridge to provide about 150A at 18V? on: March 27, 2013, 09:27:57 am
What if you use a simple low-current H-bridge IC to drive 2 automotive relays?

I guess the switching delay of the relay might be a downside, but if it isn't, there a few special and automotive relays that can handle 150A. It is common for automotive relays to handle 150A, but they usually work at 12V.

Even an L293D could drive these relays, and it is pretty easy and straightforward to drive a L293D using an Arduino.
236  International / Portugues / Re: Dúvidas Arduino para Projetos Comerciais on: March 27, 2013, 09:10:44 am
teria então como eu usar o meu arduino mega, com ISP, para gravar o Attiny85 sem usar o bootloader? tipo usando AVRDude ou algum compilador sem estar usando a IDE do arduino, como eu não possuo gravador queria ver se é possível...

Sim, e sem precisar do bootloader.

Usando o sketch ArduinoAsISP, você pode transferir qualquer .HEX para seu ATTiny85 usando seu Mega. Pode-se usar o AVRdude para isto.

O mapeamento ICSP (ou ISP como preferem alguns) do Attiny45 ou 85 é assim:

MISOPino 1
+5VPino 2
SCKPino 3
MOSIPino 4
GNDPino 6

Exceto pelo RESET, todos os outros pinos conectam no pino correspondente do Arduino (MOSI com MOSI, SCK com SCK, etc). Pelo Sketch, o Arduino gera o sinal de RESET no pino 10 (no UNO). Então o pino 10 do Arduino liga no pino 5 do Attiny85.

Veja a documentação do Mega para saber a quais pinos correspondem os pinos do UNO acima. É bem provável que sejam os mesmos, mas não posso afirmar.

Lembre-se que se o Attiny85 estiver "virgem", você precisa setar os FUSES dele antes de enviar qualquer sketch. Quais são e quais os valores a serem setados depende de como ele será usado na placa final.

A grande vantagem é: usando assim, diretamente via ICSP, você economiza uma boa memória do seu Attiny.
237  International / Portugues / Re: Dúvidas Arduino para Projetos Comerciais on: March 27, 2013, 08:49:08 am
Olá bubulindo!

Procurei mais informações (fonte) sobre as licenças do Arduino, e o que pode e não pode é:

Can I build a commercial product based on Arduino?

Yes, with the following conditions:
  • Physically embedding an Arduino board inside a commercial product does not require you to disclose or open-source any information about its design.
  • Deriving the design of a commercial product from the Eagle files for an Arduino board requires you to release the modified files under the same Creative Commons Attribution Share-Alike license. You may manufacture and sell the resulting product.
  • Using the Arduino core and libraries for the firmware of a commercial product does not require you to release the source code for the firmware. The LGPL does, however, require you to make available object files that allow for the relinking of the firmware against updated versions of the Arduino core and libraries. Any modifications to the core and libraries must be released under the LGPL.
  • The source code for the Arduino environment is covered by the GPL, which requires any modifications to be open-sourced under the same license. It does not prevent the sale of derivative software or its inclusion in commercial products.

In all cases, the exact requirements are determined by the applicable license. Additionally, see the previous question for information about the use of the name “Arduino”.

Então, eu mesmo tinha alguns conceitos errados, e falei coisa errada antes (me desculpem).

De qualquer forma, eu permaneço com minha idéia de que não vale a pena ter o bootloader do Arduino em um projeto comercial (sobretudo no produto final), pois dificulta o "field-upgrade" e consome memória flash desnecessariamente. Use ICSP com um USBasp e pronto.
238  International / Portugues / Re: Dúvidas Arduino para Projetos Comerciais on: March 27, 2013, 07:08:01 am
5) Licença, se não me engano é possível usar o Arduino comercialmente, se deixar claro que esta usando... isso?

Não. Tudo que você faz que tem uma placa de arduino ou bootloader do Arduino deve permanecer open source / open hardware.

Tecnicamente, a parte do Arduino que te interessa é o bootloader, pois você não vai "vender" um produto comercial pronto usando uma placa pronta de Arduino. Pra começar que ficaria muito caro pra você. No entanto, em um produto comercial, você não vai sequer usar o bootloader do Arduino: você vai fazer seus sketches na IDE e transferí-los para o uC usando ICSP, portanto o bootloader é completamente desnecessário e sequer precisa ser gravado na placa.  Resultado: você fez todo o desenvolvimento usando o Arduino, placa e bootloader, mas não fica nada de arduino no produto final, entendeu?!  smiley-wink

Eu já desenvolvi 4 projetos usando o Atmega328 em placas minhas. Um deles é um clone de um Arduino, mas sem a interface USB (eu uso um adaptador FTDI). Ele é o único que possui o bootloader. Como eu tenho meu clone, eu deixo meu UNO guardadinho e raramente o uso. Se meu "Arduino"  (que chamei de Simduino, para lembrar que é simples) quebrar, sujar, arranhar, amassar, queimar (desde que não o uC), eu jogo a placa fora e faço outra por custo muito baixo, e ainda aproveito vários dos componentes da anterior.

Nos outros 3, eu exponho uma interface ICSP apenas para gravação do programa (o arquivo .HEX gerado pela IDE), usando um USBasp. As placas destes 3 projetos nada têm a ver com o Arduino, mas todo o desenvolvimento do firmware delas é feito usando a IDE do Arduino.

Eu tenho comprado os Atmega328 e 328P na Amazon. Compro em lotes de 10 a 20 e eles chegam tranquilamente. Em breve passarei a usá-los apenas em SMD.

Vou ver se posto fotos do meu clone depois.
239  Using Arduino / Programming Questions / Re: Crazy project on: March 27, 2013, 06:50:38 am
I can see in the Serial Monitor that it has moments when reading the keys or not
You've got "delay(1000)" in there - what do you expect?

Bulls eye! I was about to post that when reading his code.

Ever since I learned about millis(), 99% of my delay() calls are gone.
240  Community / Exhibition / Gallery / Re: Heated water bowl for the backyard wildlife on: March 27, 2013, 06:47:36 am
Very nice project!  People who care about animals are always good people. Congratulations, Sir!

Now to the tech stuff:
- Is the thin-film heater a Peltier plate ?
- What's with the black board (PSU?) in the left side in the last picture? What is there more than a power source?
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