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81
Project Guidance / Re: SD Card Cloner Feasible
Last post by CrossRoads - Today at 05:38 am
Feasible, yes.
Could be slow with 16 MHz processor.
For USB, need a USB Host shield, or USB Host capability.
82
@ nick.. +1

Doc
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Well first off, you HAVE to have some kind of converter from mains AC to local DC. I'm not qualified to say if that conversion is easy to do if you roll your own: I do think though that dabbling in mains power without knowing exactly what you're doing is dangerous. I can say nothing other than you should get an off-the-shelf ac-dc converter. So you need to put that inside the box of the "unit" and just have a mains wire coming out of there.

I doubt if anyone here will encourage you to do the ac mains to dc 12v by any other means than off-the-shelf.

But you can get one that goes to 12V and then drop that to that 5 or 8 or whatever is required with components like 7805 which is inefficient but does work.

Go and have a look at Pololu: they have a huge range of voltage converters so if you get the 12VDC sorted from the mains ac, they have various devices to get you to other dc voltages. I have their 2120 for example.

Then regarding the motors. It's not easy to control a dc motor as carefully as you might need. So you should probably investigate both stepper motors and servos to see if they can do what you need. Steppers as the name implies move in well controlled steps of usually 1.8 degrees (200 per revolution); might be good for the auger.  Servos move to a degree position, usually between 0 and 180 and are good for raising and lowering.

There are libraries  to drive steppers and servos. Have a look at Pololu for stepper driver modules which take care of the electronics. Servos are dead simple.





edit... And pololu have modules with h-bridges to drive dc motors. Steer clear of old technology modules that use 293 or 298 chips... very wasteful of energy. I have a Pololu 2130 and it's good.
84
Hardware / problemas con arduino mega 256...
Last post by fernando_reyesl - Today at 05:27 am
al tratar de cargar un sketch me aparecen estos errores

avrdude: stk500v2_ReceiveMessage(): timeout

avrdude: stk500v2_getsync(): timeout communicating with programmer

podria estar daƱado el arduino?

85
Project Guidance / Re: Problem with Arduino bluet...
Last post by mykiscool - Today at 05:24 am
I changed that and it wasn't the problem (although still a good thing to do). The relay is behaving very weird. When I plug in the arduino the relay digital port is set to off (verified by an led wired in parallel). The relay still turns on. When I set the pin to high the relay turns off. Here's the strangest part. If I unplug the relay signal which is connected to the arduino digital, it then turns off. It is confusing since it should not be getting power just as it is not getting power when the pin is low. Is it something to do with the common ground?
86
General Electronics / Re: Arduino AC dimmer circuit
Last post by raschemmel - Today at 05:21 am
Quote
Switching the neutral (without simultaneously switching the hot) is unsafe because you would end up with a load that is off but still live.  More importantly, the screw shell on the lightbulb (connected to neutral) would be live when the dimmer and bulb are off, and would be a shock hazard if you touch it while unscrewing the bulb. 
Thank you. Good explanation.
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Awesome piece of work ! Gold Star !
88
Code: [Select]

struct r2word {
  r2sound soundA;
  int soundRepet;
  int repdelay;
  int order[6] = {0};
  //r2word(r2sound soundA, int repdelay, int order[6]) : soundA(soundA), repdelay(repdelay), order(order) {};
};


You can't initialize non-const members like that. As the message says, do that in a constructor. For example, this fails:

Code: [Select]
struct foo
  {
  int bar [10] = {0}; 
  };
 
void setup () { }
void loop () { }


Code: [Select]
sketch_nov26b:3: error: a brace-enclosed initializer is not allowed here before '{' token
sketch_nov26b:3: error: ISO C++ forbids initialization of member 'bar'
sketch_nov26b:3: error: making 'bar' static
sketch_nov26b:3: error: invalid in-class initialization of static data member of non-integral type 'int [10]'


This works:

Code: [Select]
struct foo
  {
  int bar [10];
  public:
    foo () { memset (&bar, 0, sizeof bar); } // constructor
  };
 
void setup () { }
void loop () { }
89
Programming Questions / Using Python on Arduino Tre
Last post by Nave - Today at 05:13 am
First of all, let me give warning. While I have done research, I am very new to the micro controller scene. So, please forgive any ignorance on my part.

I want to program Arduino using python because it's easier then C++. I know that programming on all current Arduino boards cannot be done with Python because of the size of the interpreter is too big for the ram.

The question I have is, would it be possible to program Arduino Tre with Python? The reason I ask is because I see that the board has 512 MB of RAM with a 1 Ghz ARM Cortex-A8 processor. I know that this isn't the micro controller processor itself but with the two processors being on the same board, shouldn't the two processors should be able to talk to each other? What I mean by this is, the Python code would run through the interpreter on the ARM Cortex-A8, then the interpreted code would then sent to the Atmel processor.


For anyone curious I am looking to use Tre for Hydroponic sensors, more specifically the sensors would be electrical conductivity, ph, air temperature, water temperature, relative humidity and C02. I would also want it to send out these readings over the internet when requested or send out a warning when sensors detects going outside a certain set of parameters. Thanks for your time
90
Project Guidance / Re: 3300 baud +-
Last post by dlloyd - Today at 05:11 am
Looks like 3300 baud rate is possible (with 0.0% error). Scroll down to the 16MHz table.

http://www.wormfood.net/avrbaudcalc.php?postbitrate=3300&postclock=16&bit_rate_table=1
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