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6226  Development / Other Hardware Development / Re: Suggestions about Mega-equivalent with built-in Ethernet on: July 29, 2011, 12:16:11 am
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If it turns out I can go switchmode for a minimal impact on BOM cost (and it fits!) I'll do it.
I did a similar design with a land pattern that could accommodate either a SOT223 or a TSR-1 switching reg.



The idea was to allow loading of one or the other according to requirements. The TSR series from Traco can handle 1A with no heatsinking. I gather that DPAK is the main regulator, the pinouts may be compatible or this would allow the use of a SOT223 as it would only be used for lower power application. Either that or just use the TSR to make life simpler.

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two connections on the TOSC pins in the chip.
I did this as well, however I had solder bridges to isolate those two IO pins ("after" the XTAL) because I figured with shields attached there would be a high capacitance on the traces due to the long runs/headers/etc.

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What external memory bus? Care to elaborate?
The 2560 is capable of using external memory chips, you could add say 1Mb of data memory (in 64k pages). This can still be done on a shield though. In my design I added a RAM chip and a few page-select signals plus battery backup. But I didn't lose space to Ethernet so had the real estate.

ALso, do you have a jumper to break the auto reset feature?

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Rob
6227  Using Arduino / Networking, Protocols, and Devices / Re: arduino reset mode not recognized on: July 29, 2011, 12:13:29 am
Quote
If it turns out I can go switchmode for a minimal impact on BOM cost (and it fits!) I'll do it.
I did a similar design with a land pattern that could accommodate either a SOT223 or a TSR-1 switching reg.



The idea was to allow loading of one or the other according to requirements. The TSR series from Traco can handle 1A with no heatsinking. I gather that DPAK is the main regulator, the pinouts may be compatible or this would allows the use of a SOT223. Either that or just use the TSR.

Quote
two connections on the TOSC pins in the chip.
I did this as well, however I had solder bridges to isolate those two IO pins ("after" the XTAL) because I figured with shields attached there would be a high capacitance on the traces due to the long runs/headers/etc.

Quote
What external memory bus? Care to elaborate?
The 2560 is capable of using external memory chips, you could add say 1Mb of data memory (in 64k pages). This can still be done on a shield though. In my design I added a RAM chip and a few page-select signals plus battery backup. But I didn't lose space to Ethernet so had the real estate.

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Rob

6228  Using Arduino / Programming Questions / Re: Concatenating from Arrays on: July 28, 2011, 11:50:19 pm
The quick and dirty way is

Serial.print(buf[0]);
Serial.print(buf[1]);

If there is nothing in the buf[2] location and the array is at least 3 bytes long

buf[2] = '\0';
Serial.print(buf);

Will there always be two chars?

Or will you always know the number of chars?


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Rob
6229  Using Arduino / Sensors / Re: LMS303 sample reading on: July 28, 2011, 11:05:47 am
No problems, I might file that away for future use myself smiley

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Rob
6230  Using Arduino / Networking, Protocols, and Devices / Re: My Project's Network Requires? on: July 28, 2011, 11:04:33 am
How about adding a "bus" option.

My personal preference (in an RS-485 low speed control network) is for all of the above, well maybe some of the above.

Basically I use a bus, but I'm not shy to have long stubs, so I guess that's a star. Also I like the idea of bringing the cable back to the source to make a sort of ring (actually a circular bus I suppose) as this allows the cable to be cut once with no loss of functionality.

Years ago I designed a ring bus for a building control system. It used HDLC protocol on optical fibers and had two rings running in opposite directions IIRC. That was very reliable.

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Rob
6231  Using Arduino / Sensors / Re: LMS303 sample reading on: July 28, 2011, 09:56:54 am
It's a shorthand version of

Code:
if (max - min > FUDGE_FACTOR)
  hstate = SPECIAL;
else
  hstate = NORMAL; 

It's called a ternary operator

x = test ? true_result : false_result;

http://cprogramminglanguage.net/c-ternary-operator.aspx

much like IIF in many other languages.

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Rob
6232  Using Arduino / Networking, Protocols, and Devices / Re: I2c Slave mode. on: July 28, 2011, 08:53:55 am
Sorry Peter I can't help.

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not a lot of people use the arduino in i2c slave mode
I would say that's the most likely case, or maybe c/.

I will have an interest in doing so soon but have no experience with it yet.

Do you know if the Arduino in slave mode can coexist with other i2c devices. You initialize wire with an address which implies so.

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Rob
6233  Community / Bar Sport / Re: Why people like Arduino on: July 28, 2011, 06:07:28 am
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May the flame Wars.begin()
Not my intention and I hope it doesn't degrade to that.

I'm fairly well versed on both sides of the fence and am well aware of the pros and cons of either side. It's just that for some reason the above example drove home to me the difference as I think a newbie would see it. In fact it's probably even worse because just getting to the stage where you are writing the first example can be a struggle whereas I suspect most people who get an Arduino will be at the second example in no time (albeit without the constant for the baud rate smiley)

And then, as Mike says, there are experienced people who just want to get a simple project up and running.

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Rob
6234  Using Arduino / Project Guidance / Re: How hard would it be to build an EPROM writer? on: July 28, 2011, 06:00:05 am
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re there any examples of what the programming would need to be to connect to a ZIF socket?
If you mean to program an EPROM I wouldn't hold your breath waiting for an example these days. Get the data sheet and go from there. It's pretty simple, put address, put data, put 12v, put write pulse, or something like that (it's been 20 years after all).

Also, get a UV light to erase them. We used to use a small flouro-style tube.

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Rob
6235  Community / Bar Sport / Why people like Arduino on: July 28, 2011, 03:49:45 am
I was just browsing a thread over at AVR Freaks and noticed this code snippet that sets up a UART

Code:

    //Set baud rate
   UBRR0H = (unsigned char)( UBRRVAL>>8 );   //high byte
   UBRR0L = (unsigned char) UBRRVAL;         //low byte

   //Asynchronous normal speed
   UCSR0A = (0<<U2X0);

   //Enable Transmitter and Receiver and Interrupt on receive complete
   UCSR0B = (1<<RXEN0)|(1<<TXEN0)|(1<<RXCIE0);

   //page 186 Set asynchronous mode,no parity, 1 stop bit, 8 bit size
   UCSR0C= (0<<UMSEL00)| (0<<UMSEL01)|          //Async
         (0<<UPM00)|(0<<UPM01)|               //Parity None
         (0<<USBS0) |                     //Stop bits 1
         (0<<UCSZ02)|(1<<UCSZ01)|(1<<UCSZ00);   //8 Bits

   //enable interrupts
   sei();
   }

Now this isn't as scary as it first looks and anyone used to working with embedded AVRs will feel quite at home with this code. But here's the Arduino equivalent

Code:
Serial.begin(BAUDRATE);

Ummm...is it any wonder that people who just want to make an interactive coffee table or even those more serious about getting into embedded processors are attracted to Arduino?

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Rob


6236  Using Arduino / Project Guidance / Re: When using Vin for input, can it handle more than 5V? on: July 28, 2011, 03:19:41 am
VIN has to be at least around 7v and HAS to go into the barrel connector (or the VIN socket on the power header). Put it anywhere else and you'll blow something up.

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Vin refer to using it as an output pin.
VIN is not a pin al all.

Maybe you should tell us exactly what you want to do before you have to buy a new Arduino smiley

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Rob
6237  Using Arduino / Networking, Protocols, and Devices / Re: RF24 Library: Driver for nRF24L01(+) 2.4GHz Wireless Transceiver on: July 28, 2011, 02:04:58 am
This does sound nice, I love the size of those modules, you could put them into just about anything.

I to have been keeping an eye on this, not ready to do anything yet though.

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Rob
6238  Using Arduino / Interfacing w/ Software on the Computer / Re: Fighting with Vista on: July 27, 2011, 11:20:57 pm
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Can I just move the folder?
Possibly, I know people install it in other places. Whether you can move an installed folder I don't know. Worst case is a new install.

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How did you turn user access control off?
Yep, it's a real pain, and my PCB package can't save files with it on.

Go to Control panel > User accounts. The bottom link can be used to toggle the UAC.

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Rob
6239  Using Arduino / Interfacing w/ Software on the Computer / Re: Fighting with Vista on: July 27, 2011, 10:48:42 pm
I assume you're talking about Arduino install files.

I have no trouble doing anything like this but I have the user access control crap turned off.

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rob
 
6240  Topics / Home Automation and Networked Objects / Re: PoolDuino - Automate my pool with Arduino on: July 27, 2011, 08:49:30 pm
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Scare you off yet?
Reminds me of what a PITA a pool can be, glad I don't have one any more.

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my liquidcrystal screen is limited in the amount of output. 16x2 is not a lot!
Simple, get a bigger one. Even better get a serial graphics LCD like the ones from 4D Systems, they have touch panels as well so you don't need buttons.

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limited in the amount of input pins I have
Either move up to a Mega or use a MUX (like the 4051 or 4067) to get more inputs.

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Rob

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